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MATERIALS AND DEVICES

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Advanced oxide materials – growth, characterization and applications

The symposium will show the state of art of functional oxides, and will be devoted to bulk and surface properties, films, nanocrystals, structure-property relationships, electronic, optical and magnetic properties. The symposium will cover current topics of advanced oxides and comprise new trends in experimental and theoretical research.

Scope:

Multiple functional and multifunctional materials belong to the large family of oxides. Applications of functional oxides attract an increasing attention. Among such oxides there is a broad diversity of structures: wurtzite, corundum, zircon, scheelite, wolframite, fluorite, spinel, garnet, perovskite, bixbyite and many others. The physicochemical properties can be tuned through variation of factors such as composition, temperature, pressure, strain, external fields, defects, film orientation and nanoparticle size. Structure-property detailed analysis and understanding of the physicochemical properties of the oxides are prerequisites to improve their properties, and to spur development of new oxide materials. The symposium will be devoted to binary and multicomponent oxides prepared in the form of bulk crystals, films, nanocrystals, nanowires, quantum dots, heterostructures, nanoparticles, nano- inclusions, etc ...

Hot topics to be covered by the symposium:

  • synthesis and crystal growth of bulk and low-dimensional oxide materials; process monitoring and control
  • structure-property relationships of functional oxides
  • properties of oxides exhibiting specific tunable and controllable properties: phase diagrams optical, electronic, catalysis, magnetism, multiferroic, superconductivity, ferroelectricity, piezoelectricity, heat transport 
  • interface structure and properties, processes studied in situ: (chemical synthesis reactions, compression, phase transitions, catalytic processes)
  • dynamical properties: charge transfer, chemical reactions, etc.
  • applications: energy related materials, energy storage, dielectrics, ferroelectrics, , electro-optics, piezoelectrics, superconductors, magnetic, ferroics and spintronic materials, materials foe catalysis, applications in biology and medicine

We expect experimental studies, theoretical modeling and prediction of properties using e.g. ab inito theoretical methods, or semi-empirical modeling. 

The goal of this symposium is to bring scientists working in various fields of materials science together which deal with synthesis, crystal and defect structure, physico-chemical properties of functional oxides from basic science to technological applications.

Invited speakers (confirmed):

  • Sarbajit Banerjee (Texas A&M University, USA) Corralling Electrons in Ternary Vanadium Oxides: Implications for Logic Circuitry and Energy Storage
  • Andrzej Calka (University of Wollongong in Australia) Novel Electro-Mechano Synthesis of Complex Oxides
  • Stefan Förster (Martin Luther University Halle-Wittenberg, Germany) Quasicrystals in ternary oxide layers
  • David Grosso (Aix-Marseille University, France) Patterned metal oxides coatings from sol-gel nano-imprinted process
  • Bjørk Hammer (Aarhus University, Denmark) Machine learning enhanced DFT search for oxide surface structures
  • Zbigniew Klusek (University of Lodz, Poland) The mystery of resistive switching - from TiO2 to graphene oxide
  • Markku Leskelä (University of Helsinki, Finland) Atomic Layer Deposition of Functional Transition Metal Oxides
  • Chiara Maccato (Padova University, Italy) H2 Photo-Production from Fe2O3 – based Nanosystems Grown by Tailored Vapor Phase Routes
  • Catherine Marichy (University Lion, France) ALD metal oxide based sensors
  • Elisabetta Comini (University of Brescia, ItalyNanostructured metal oxides for chemical sensors
  • Andre ten Elshof (University of Twente, the Netherlands) 2D oxide nanosheets as single-crystal templates to control the growth orientation and properties of functional oxides
  • Jan Macak (University Pardubice, Czech Republic) ALD functionalized Self-Organized TiO2 Nanotube layers for Applications
  • Naoki Ohashi (NIMS, Japan) Defect and Hydrogen Impurity in zinc oxide studied with various single crystals
  • Gareth Parkinson (Technology University of Wien, Austria) The interaction of Water with Iron-Oxide Surfaces
  • Wilfrid Prellier (CNRS, France) Chemical strain engineering of magnetism in PrVO3 thin films
  • Radosław Przeniosło (University of Warsaw, Poland) Magnetic and crystal structure symmetry in oxides
  • Alex Shluger (University College London, UK) Role of Carrier Injection in Degradation of Thin Oxide Films
  • Patrik Schmuki (University of Erlangen, Germany) Highly aligned oxide nanotubes for energy applications
  • Annabella Selloni (Princeton University, USA) Photocatalysis on TiO2: insight from simulations
  • Susan Trolier-McKinstry (Pennsylvania State University, USA) Piezoelectric films for logic devices
  • Andrzej Turos (Institute of Electronic Materials Technology, Poland) Mechanism of damage built-up in ion bombarded ZnO
  • Ilia Valov (Research Centre Jülich, Germany) Nanoscale electrochemistry using oxide dielectric thin films as solid electrolytes

Scientific committee:

  • Jaan Aarik, Estonian Academy of Sciences, Estonia
  • Davide Barreca, ICMATE-CNR and INSTM, Padova, Italy
  • Richard Catlow, University College, UK
  • Hanna Dabkowska, University of Hamilton, Canada
  • Ulrike Diebold, Technishe Uinversity Vienna, Austria
  • Judith Driscoll, University of Cambridge, UK
  • Karol Frohlich, Slovak Academy of Sciences, Slovakia
  • Johannes Heitmann, Technical University Freiberg, Germany
  • Hideo Hosono, Tokyo University of Technology, Japan
  • Edwin Lundgren, Lund University, Sweden
  • Michel Mortier, Institute of Research in Chemistry, CNRS, France
  • Giafranco Pacchioni, University of Milano, Italy
  • Wojciech Paszkowicz, Polish Academy of Sciences, Poland
  • Lionel Santinacci, CNRS, Marseille, France
  • Jörg J. Schneider, TU Darmstadt, Germany
  • Margit Zacharias, University Freiburg, Germany
  • Chih-Chung Yang, National Taiwan University, Taiwan
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Session 1: Oxide-Based Sensors : Elzbieta Guziewicz (Poland)/Gareth Parkinson (Austria)
09:00
Authors : E. Comini, A. Bertuna, N. Kaur, H. M. M. Munasinghe Arachchige, N. Poli, M. Rizzoni, O. Sisman, D. Zappa, G. Sberveglieri
Affiliations : SENSOR lab, Dipartimento di Ingegneria dell?Informazione, Università degli studi di Brescia, via valotti 9, Brescia, Italy

Resume : Metal oxides materials show properties covering almost all aspects of material science and physics in areas including electronics, superconductivity, ferroelectricity, magnetism. In particular, metal oxides are already established in the field of gas sensing. The most common sensing mechanism consists in an electrical resistance variation upon gas chemisorption. The advantages of using single crystal nanowire of metal oxides compare to films are numerous: a very large surface-to-volume ratio; the downsizing of sensing materials, which improves the sensor performances; enhanced stability (high degree of crystalline order); the higher capability to accommodate strain in presence of lattice mismatch. The main challenges remains the integration in macroscopic devices with good and stable electrical contacts [1][2]. Many different binary oxides (i.e. tin, zinc, copper, nickel, tungsten and niobium oxide) and heterostructures (i.e. NiO-ZnO and graphene oxide-SnO2) were synthesized at SENSOR Laboratory directly on destination substrates by using vapor-liquid-solid technique, thermal oxidation and hydrothermal methods. These materials were fully characterized by mean of morphological and structural investigations, using FE-SEM, TEM, XRD, XPS, Raman and EDX spectroscopies.. Functional properties of these structures as gas sensors were tested to different pollutants like CO, NO2, Ozone and many VOCs, showing the capability to use the devices in real applications. Acknowledgements This work was partially supported by the European Community?s 7th Framework Programme, under the grant agreement n° 611887 ?MSP: Multi Sensor Platform for Smart Building Management?. References [1] Wang, X.S., Miura, N. and Yamazoe, N., Sens. Actuator B-Chem. 2000, 66(1-3), 74 [2] Meng, D., Shaalan, N.M., Yamazaki, T. and Kikuta, T., Sens. Actuator B-Chem. 2012, 169, 113

N.1.1
09:30
Authors : C. Marichy
Affiliations : Univ. Lyon, Université Lyon 1, CNRS, LMI UMR 5615, F-69622 Villeurbanne, France

Resume : Among the various types of chemical gas sensors, resistive gas sensors are attractive because of their high sensitivity, stability, low cost and fast response. In particular, metal oxide (MOx) semiconductors, such as SnO2, ZnO and TiO2, have been widely studied as active layer. However, performances of sensors and their selectivity are strongly dependent of the morphology, structuration and nature of the active material. In particular, due to the strong correlation between grain size and sensor response, nanostructured and/or heterostructured materials permit an enhancement of the gas sensing response. Such structuration requires versatile and well-controlled elaboration approach. Atomic layer deposition (ALD) thus appears as a technique of choice due to its simplicity, reproducibility, the atomic scale precision of the deposited thickness and high homogeneity of the obtained films. Herein, it will be shown that ALD has proven to be well-suited for the elaboration of compact thin films, nanostructures and heterostructures to be applied for the detection of a variety of analytes. We aim at summarizing the most significant progresses related to gas sensors based on ALD MOx thin films, nanostructures and heterostructures. We will also shortly discuss the nanostructure properties in parallel to the sensing mechanisms in order to try to develop clear structure?property correlations.

N.1.2
10:00
Authors : Tetsuya YAMAMOTO, Junich NOMOTO, Keisuke KOBAYASHI, Hisao MAKINO
Affiliations : Kochi University of Technology, Japan

Resume : We report a high-response hydrogen (H2) gas sensor based on a 50-nm-thick conductive Ga-doped ZnO (GZO) polycrystalline films. The GZO films were deposited on glass substrates at a temperature of 200 Celsius by ion plating with direct-current arc discharge. The Ga2O3 content in the ZnO targets were 3 wt.%. In this study, we assume the chemical reaction limiting the performance of H2 gas sensors should be as follows: the reaction of H2 gas with an electronegative oxygen (O-) ion adsorbed at a grain boundary produces a water molecule together with a free electron, resulting in a decrease in the electrical resistivity. We have been developing an afterarc plasma technique to generate O- ions for the control of the density and chemical states of the different types of O-related defects. Analysis of the data obtained by X-ray photoelectron spectroscopy measurements indicated the irradiation of O- ions with positive bias to the substrates with GZO films led to an annihilation of oxygen vacancies at the surface of the GZO films, resulting in a decrease in the density of adsorbed sites that can limit the performance of the sensors at the ingrain surfaces. Analysis of Hall effect measurement results and of optical measurement results combined with Drude model suggested the formation of a high and narrow energy barrier at a grain boundary in addition to the energy barrier owing to the nature of the grain boundaries such as discontinuity and disorder after O- irradiation. We confirmed the distinctly enhanced performance of H2 gas sensors based on the GZO films; fast response within 1 second at a temperature of 330 Celsius. We will propose a theoretical model to clarify the effects of O- irradiation on H2 gas sensing mechanism.

N.1.3
10:15
Authors : L. von Helden1, M. Schmidbauer1, C. Feldt1, D. Braun1, M. Hanke2, Y. Dai3, R. Wördenweber3, J. Schwarzkopf1
Affiliations : 1Leibniz Institute for Crystal Growth (IKZ), Berlin; 2Paul-Drude-Institute for Solid State Electronics (PDI), Berlin; 3Peter-Gruenberg-Institute (PGI), Forschungszentrum Jülich, Germany

Resume : Ferroelectric materials are of interest for a wide range of technological applications like, e.g., ferroelectric random access memories (FRAMs) or nanosensors. In particular, piezoelectric sensors based on surface acoustic waves (SAW) in thin films are expected to provide a larger signal-to-noise ratio compared to bulk materials and would therefore enable the detection of a single molecule attaching to a surface. However, only little is known about how SAWs depend on the structural properties and the ferroelectric domain structure of a thin film. In this study, compressively strained K0.7Na0.3NbO3 thin films were grown with (001)pc pseudocubic surface orientation by metal organic chemical vapor deposition (MOCVD) on (110) TbScO3 substrates. As a result, a periodic domain pattern with domain walls running along [-112]TSO and [1-12]TSO have been detected. Piezoresponse force microscopy and high resolution X-ray diffraction measurements verify the formation of 90° monoclinic MC domains. In preliminary SAW experiments distinct propagation directions are found that coincide with the four monoclinic shearing directions of the ferroelectric MC domain pattern. The SAW signals could be examined in 1st and 3rd order with corresponding sound velocities of 3360 m/s and 9860 m/s, respectively. Both resonances were detected with a transmission coefficient of 4 dB, which is a quite promising result indicating a higher signal-to-noise ratio than in bulk SAW devices.

N.1.4
10:30 Coffee break    
 
Session 2: Surface and Nanostructures : Wojciech Paszkowicz (Poland)
11:00
Authors : Bjørk Hammer
Affiliations : VILLUM Investigator Department of Physics and Astronomy Aarhus University, Denmark

Resume : The use of an evolutionary algorithm in conjunction with density functional theory (DFT) has been proven a powerfull tool, e.g. for determining the structure of atomic steps on single crystalline rutile TiO2(110)[1,2,3]. The determined structures have subsequently formed the basis for activity studies of such steps[4,5]. Progress with finding surface structures of more complicated oxide systems has been hampered by the high computational demand of the DFT computations required by evolutionary algorithms. To speed up the structure search, it is proposed to augment the evolutionary method using machine learning techniques. As a first approach towards this, we have introduced clustering - an unsupervised machine learning technique - to label intermediate structures emerging from the evolutionary approach[6]. The labelling allows for rational decisions to be made when parent structures are chosen during the evolutionary run - decisions that are shown to speed up the structural search[6]. Current work involving supervised machine learning techniques that establish the relative stability of structural parts in parent structures will further be outlined. The resulting local energies allow for rational strategies for cross-over and mutation events on parent structures. [1] Steps on rutile TiO2(110): Active sites for water and methanol dissociation. U. Martinez, L. B. Vilhelmsen, H. H. Kristoffersen, J. Stausholm-Møller, B. Hammer, Phys. Rev. B 84, 205434 (2011). DOI: 10.1103/PhysRevB.84.205434 [2] Packing defects into ordered structures: strands on TiO2. R. Bechstein, H. H. Kristoffersen, L. B. Vilhelmsen, F. Rieboldt, J. Stausholm-Møller, S. Wendt, B. Hammer, and F. Besenbacher, Phys. Rev. Lett. 108, 236103 (2012). DOI: 10.1103/PhysRevLett.108.236103 [3] A density functional theory study of atomic steps on stoichiometric rutile TiO2(110). J. Stausholm-Møller, H. H. Kristoffersen, U. Martinez, and B. Hammer, J. Chem. Phys. 139, 234704 (2013). DOI: 10.1063/1.4840515 [4] Reduced step edges on rutile TiO2 as competing defect to oxygen vacancies on the terraces and reactive sites for ethanol dissociation. U. Martinez, J. Ø. Hansen, E. Lira, H. H. Kristoffersen, P. Huo, R. Bechstein, E. Lægsgaard, F. Besenbacher, B. Hammer, and S. Wendt, Phys. Rev. Lett. 109, 155501 (2012). DOI: 10.1103/PhysRevLett.109.155501 [5] Role of steps in the dissociative adsorption of water on rutile TiO2(110). H. H. Kristoffersen, J. Ø. Hansen, U. Martinez, Y. Y. Wei, J. Mathiesen, R. Streber, R. Bechstein, E. Lægsgaard, F. Besenbacher, B. Hammer, and S. Wendt, Phys. Rev. Lett. 110, 146101 (2013). DOI: 10.1103/PhysRevLett.110.146101 [6] Combining Evolutionary Algorithms with Clustering toward Rational Global Structure Optimization at the Atomic Scale. M. S. Jørgensen, M. N. Groves, and B. Hammer, J. Chem. Theo. and Comput, 13, 1486 (2017). DOI: 10.1021/acs.jctc.6b01119

N.2.1
11:30
Authors : Raul Zazpe, Hanna Sopha, Jan Prikryl, Milos Krbal, Siowwoon Ng, Jan M. Macak
Affiliations : Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, Nam. Cs. Legii 565, 530 02 Pardubice, Czech Republic

Resume : The self-organized TiO2 nanotube layers have attracted considerable scientific and technological interest over the past 10 years motivated for their possible range of applications including photo-catalysis, solar cells, hydrogen generation and biomedical uses. The synthesis of 1D TiO2 nanotube structure is carried out by a conventional electrochemical anodization of valve Ti metal sheet. The main drawback of TiO2 is its applicability in the UV light (wavelengths < 390 nm). In order to enhance the efficiency, TiO2 has been doped by N or C o to shift its absorption into the visible light. Except of doping, one of the major issues to extend the functional range of nanotubes is to coat homogenously tube interiors by a secondary material. It has been shown that additional ultrathin surface coating of TiO2 by secondary materials such as Al2O3, ZnO or MgO annihilates electron traps at the TiO2 surface and thus increases the photogenerated concentration of charge carriers. Recently, it has been demonstrated that just a single cycle of Al2O3 or ZnO deposited by atomic layer deposition (ALD) efficiently improve charge transport properties of the heterostructure while gradual passivation appears with increasing ZnO thickness due to stronger band-bending. The presentation will focus in detail on the coating of the nanotube arrays by secondary materials using ALD. The deposited materials influence strongly photo-electrochemical properties of nanotube films. Experimental details and some very recent photocatalytic, solar cell and sensing results will be presented and discussed.

N.2.2
12:00
Authors : A. Freitas1,2, R-K. Ramamoorthy2, M-A. Neouze1, E. Larquet2, F. Testard1,T. Gacoin2, D. Carrière1
Affiliations : 1:LIONS, NIMBE, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette Cedex 2 : LPMC (UMR 7643), CNRS-École polytechnique, Route de Saclay, 91128 Palaiseau, FRANCE

Resume : Among families of nanoparticles, oxide nanoparticles synthesised in water are quite peculiar as they tend to form similar morphologies. For instance, titanium oxide, zirconium oxide, zinc oxide, cerium oxide, yttrium vanadate, sized in the 20-150nm range, are made of aggregated crystalline primary grains1.This two-level structuration is the possible signature of a general non-classical nucleation path, where crystallisation by aggregation2 prevails over ion-by-ion growth. Deeper understanding is a key issue when intending to optimise the development of functional materials involving these particles (nanocomposites, thin films, biological labels?). To date, the control and understanding of the nanostructuration is hampered by the lack of direct, in situ, experimental observations of the nucleation process, a subject that we intend to investigate on a model system. Here, we study the synthesis of YVO4:Eu nanoparticles by coprecipitation in water, upon mixing two aqueous precursors3. This synthesis is a good model system to study two paradigmatic cases: tuning the pH of the vanadate precursor, we obtain either ?classical? polycrystalline particles of 40 nm composed of primary grains of 2 to 5 nm, or monocrystalline-like particles of 40 nm. To explain this difference in structure, in situ luminescence, pH and SAXS/WAXS studies were conducted simultaneously, from reaction times as short as 5ms. In particular, we demonstrate that the nanostructure is driven by a secondary nucleation from transient disordered intermediate states that we were able to capture in the millisecond range.

N.2.3
12:15
Authors : Taemin Ludvic Kim, Ho Won Jang
Affiliations : Seoul National University, Korea

Resume : Interfacial phenomena are attracting substantial interest from both fundamental and practical points of view due to the diverse properties vary with the attached materials and their applicability. The interface between different materials in heterogeneous structures plays an important role in many devices such as transistors, lasers, and solar cells. Manipulation of the interface or surface band diagram, which defines the electronic properties of these devices, can be achieved via charges originated from dopant ions, ferroelectric polarization, surface adsorbates, and so on, all of which can electrostatically modify the electron energies nearby. Here we demonstrate a highly interfacial phenomenon that controls the out-of-plane transport properties. The electrical property and photoelectrochemical properties of WO3/LaAlO3/Nb:SrTiO3 heterostructure is measured. The electrical conductivity of the structure can be tuned to be transparent by inserting a wide-band gap insulator (5.6 eV) LaAlO3 with thickness of 0 to 3 unit cells. This counterintuitive result, that an interfacial barrier can be driven transparent by inserting a wide-gap insulator, arises from the large internal electric field between the two polar LaAlO3 surfaces. This field modifies the effective band offset in the device, highlighting the ability to design the electrostatic boundary conditions with atomic precision.

N.2.4
12:30 Lunch break    
 
Session 3: Surface Chemistry and Catalysis : Jan Macak (Czech Republic)
13:45
Authors : Gareth S. Parkinson
Affiliations : Institute of Applied Physics, TU Wien, Vienna, Austria

Resume : The interaction of water with iron-oxide surfaces is important in geochemical and weathering processes, and fundamental to the applications of these fascinating materials in technology [1]. In this talk, I will discuss the adsorption of water on magnetite (Fe3O4) and hematite (?-Fe2O3) single crystals. The former material is the industrial catalyst for the water-gas shift reaction (CO+H2O --> CO2+H2), while the latter a promising cathode for photoelectrochemical water splitting. The work combines atomically-resolved scanning probe microscopy and spectroscopic measurements, with density functional theory-based calculations. Experiments were conducted under ultrahigh vacuum (UHV) conditions, and in liquid water using a new electrochemical setup at the TU Wien. The first part of the talk will focus on Fe3O4(001), which undergoes a (?2×?2)R45° reconstruction due to an ordered array of subsurface cation vacancies and interstitials [2]. Water adsorbs weakly, with four distinct peaks between 200 and 250 K in temperature programmed desorption (TPD) spectra. The peaks correspond to water coverages of 9, 8, 6 and 3 molecules per (?2×?2)R45° unit cell. Theoretical calculations find that only partially dissociated water agglomerates with the corresponding sizes are stable species over the range of water chemical potential. We conclude that magic water clusters occur when the water-substrate interaction is weak, and the cation-cation distance is sufficiently short that significant hydrogen bonging can occur. Water adsorbs more strongly on the ?-Fe2O3(012) surface, despite the fact that the surfaces are similar in many respects. Indeed, water adsorbs in a mixed-mode configuration, but desorbs in a single TPD peak at ?350 K. Possible geometric reasons for the behavior will be described, and conclusions discussed in the context of the adsorption of water on metal oxide surfaces in general. References [1] Parkinson, G. S., Iron Oxide Surfaces. Surface Science Reports 2016, 71, 272-365. [2] Bliem, R., et al., Subsurface Cation Vacancy Stabilization of the Magnetite (001) Surface. Science 2014, 346, 1215.

N.3.1
14:15
Authors : Xunhua Zhao, Sencer Selcuk, Annabella Selloni
Affiliations : Department of Chemistry, Princeton University, Princeton, NJ 08544, USA

Resume : We discuss recent applications of first principles electronic structure calculations and molecular dynamics simulations to understand materials properties and reaction mechanisms in TiO2-based photocalysis. We focus on the behavior of charge carriers at anatase TiO2 surfaces and aqueous interfaces, and the formation and structure of so-called black TiO2, a promising functional material capable to absorb the whole spectrum of visible light.

N.3.2
14:45
Authors : Maximilian Schaube, Rotraut Merkle, Joachim Maier
Affiliations : MPI for Solid State Research, Heisenbergstr. 1, Stuttgart, Germany

Resume : The incorporation of oxygen into metal oxides is one major research field in solid state ionics since a deep understanding of this mechanism is necessary for well-directed design of materials for e.g. energy storage, membranes or catalysis. The incorporation of oxygen depends on a complex network of reactions such as chemisorption, dissociation and incorporation. The reaction rate is expected to depend on the concentration of ionic (e.g. oxygen vacancies) as well as electronic defects (electrons, holes, mixed valent cations), see e.g. [1,2]. The role of such defects on the oxygen exchange kinetics can be elucidated by systematic variation of dopant type and concentration. Oxygen exchange was investigated by pulsed oxygen isotope exchange [3] on ceria particles containing 0.6-20 mol% of dopants: Gd3+ leading to oxygen vacancy formation, Pr3+/4+ creating oxygen vacancies and/or redox activity, and Nb5+ causing the formation of conduction electrons and/or oxygen interstitials. Pr-doped samples exhibit a higher exchange activity compared to Gd-doped ceria. From the formation rate of 16O18O molecules, conclusions on the relative rates of the dissociation and incorporation step can be drawn. Annealing of the doped ceria particles at 1400 °C prior to the exchange experiment was found to increase the oxygen exchange rate. Surface analytical investigations are in progress to elucidate this effect. [1] L. Wang, R. Merkle, Y. A. Mastrikov, E. A. Kotomin, J. Maier, J. Mater. Res. 27 (2012) 2000 [2] M. M. Kuklja, E. A. Kotomin, R. Merkle, Y. A. Mastrikov, J. Maier, Phys. Chem. Chem. Phys. 15 (2013) 5443 [3] H. J. M. Bouwmeester, C. Song, J. Zhu, J. Yi, M. v. S. Annaland, B. A. Boukamp, Phys. Chem. Chem. Phys. 2009, 11, 9640.

N.3.3
15:00
Authors : Marcin R. Zemla, Kamil Czelej, Piotr Spiewak, Tomasz Wejrzanowski, Krzysztof J. Kurzydlowski
Affiliations : Technology Partners Foundation, 5A Pawinskiego St, 02-106 Warsaw, Poland

Resume : Over the past few years, much effort has been devoted toward understanding the wettability and design of new hydrophobic surfaces for a number of applications, such as anti-icing, dropwise condensation, droplet impact resistance, drag reduction, anticorrosion, and electro-wetting. Recently, the hydrophobicity of rare-earth oxides (REOs) has been observed experimentally and subsequently scrutinized using electronic structure density functional theory (DFT) calculations. In this work, we applied the DFT method to analyze the possibility of tuning the wettability of commonly used hydrophilic Al2O3 by surface doping with RE elements. A slab geometry was used to model the most stable, low-index surfaces observed experimentally for Al2O3. In the cases of RE elements on site Coulomb interaction (U) have been taken into account according to Dudarev approach. The calculations indicate that Ce can preferentially segregate to the surface of Al2O3 and form a Ce-rich oxide layer, which is stable under a wide range of oxygen chemical potentials. A remarkable increase in the water contact angle is predicted for Ce-doped Al2O3(0001). The wetting properties of Ce-doped Al2O3 are governed by two factors: 1) the unique electronic structure of the rare-earth metal promotes hydrogen bond formation between H2O and surface oxygen; 2) significant relaxation of the surface Ce and O atoms hampers direct interaction between H2O and Al cations, preventing dissociative water adsorption. These results provide a valuable opportunity for Al2O3 surface modification, in terms of achieving hydrophobicity

N.3.5
15:15
Authors : Kei Noda, Takahiro Ohta, Hikaru Masegi
Affiliations : Dept. of Electronics and Electrical Engineering, Keio University, Yokohama, Japan.

Resume : To date, a large number of evaluations for photocatalysis based on liquid-phase reactions have been carried out, where gas analysis during photocatalysis mainly detects only final products. On the other hand, evaluation of photocatalytic reactions in high vacuum has an advantage that intermediate products can be observed at a real-time scale. In this study, Real-time observation of gas-phase photocatalytic reaction processes with anodized iron oxide nanotube arrays (FNAs) in high vacuum was performed by utilizing a home-made apparatus, in order to investigate the relationship between materials properties and photocatalytic functions of FNAs in detail. FNAs were prepared by anodizing pure iron foils with ethylene glycol based electrolyte containing ammonium fluoride and pure water. X-ray diffraction measurement suggested that post-annealing FNAs in air resulted in the formation of a mixture of hematite (Fe2O3) and magnetite (Fe3O4). After that, platinum nanoparticles as co-catalyst were deposited on the prepared samples by photodeposition with different deposition time. Photocatalytic decomposition of gaseous methanol over the Pt-loaded FNAs under visible light illumination was examined. As a result, switching phenomena in the partial pressures of H2, carbon monoxide (CO), and water (H2O) were observed simultaneously according to the ON/OFF sequence of the light illumination, while no change in these gas species appeared for FNAs without Pt and bare iron foils. It may be concluded that visible light responsive photocatalysis clearly appeared due to the combination of FNAs and Pt, facilitating decomposition of gaseous methanol and simultaneous proton reduction toward hydrogen gas evolution.

N.3.6
15:30 Coffee break    
 
Session 4: Low-Dimensional Structures for Novel Applications : Bjork Hammer (Denmark)
16:00
Authors : S. Förster1 and W. Widdra1,2
Affiliations : 1Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, Halle, Germany 2Max-Planck-Institut für Mikrostruktruphysik, Halle, Germany

Resume : When approaching the two-dimensional limit, oxides are known to exhibit strong variations in their structures and properties as compared to the respective bulk materials. One of the extreme examples are the two-dimensional oxide quasicrystals (OQCs), which have been discovered for reduced perovskite oxides thin films of BaTiO3 and SrTiO3 at the Pt(111) interface [1, 2]. Low-energy electron diffraction (LEED) reveals a twelve-fold rotational symmetry. Scanning tunneling microscopy (STM) at room temperature as well as at low temperatures (80 K) allows to resolve the atomic structure. The aperiodic structure is formed by primitive atomic arrangements in squares, triangles, and rhombi according to a Nizekii-Gähler tiling. In addition to this dodecagonal atomic arrangement, building blocks of squares, triangles, and rhombi are also found on (2+√3) larger scales indicating the characteristic self-similarity of an ordered QC. Besides the QC itself also various approximant structures are found, in which selected motifs of the OQC are periodically repeated. Recently, the full structural analysis of a simple approximant allowed to propose a model for the main building blocks of these two-dimensional layers [3]. [1] S. Förster K. Meinel, R. Hammer, M. Trautmann, W. Widdra, Nature 502, 215 (2013) [2] S. Schenk et al., J. Phys: Condens. Matter 29, 134002 (2017) [3] S. Förster et al., Phys. Rev. Lett. 117, 095501 (2016)

N.4.1
16:30
Authors : J.E. ten Elshof
Affiliations : MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, the Netherlands

Resume : Metal oxide nanosheets are the oxide equivalents of graphene. They have thicknesses of 0.5-2.5 nm and lateral sizes up to tens of micrometers. Oxide nanosheets are made by delamination of layered metal oxides in water using a combination of acid-base & ion exchange reactions. Since nanosheets are 2D single crystallites with only one type of surface termination, they are versatile seed layers for growth of oriented and epitaxial functional metal oxides. For example, oriented perovskite-type thin films of SrRuO3, (La,Sr)MnO3, Pb(Zr,Ti)O3 and BiFeO3 have been grown on Ca2Nb3O10 and Ti0.87O2 nanosheets using pulsed laser deposition. Depending on the nature of the nanosheet seed layer, either [001] or [110] oriented perovskite films were formed, and the ferromagnetic and ferroelectric properties were shown to depend on the preferential orientation of the as-grown films. Moreover, the lateral sizes of the nanosheets offered another independent parameter to modulate the properties of these films further. Also anatase has been grown from aqueous solution onto different nanosheet templates, resulting in high aspect ratio anatase crystals with different external facets. The photocatalytic activity of these systems for hydrogen formation from methanol solutions was shown to depend on the nature of the exposed facets.

N.4.2
17:00
Authors : Sang Jin Lee1,2, Yekyung Kim1, Hyeongkeun Kim1, Sahn Nahm2, Seung Ho Han1,*
Affiliations : 1Electronic Convergence Materials & Device Research Center, Korea Electronics Technology Institute, Gyeonggi-do 13509 Korea; 2Department of Materials Science and Engineering, Korea University, Seoul 02841, Korea

Resume : Transparent conducting oxide (TCO) has been employed in various device industries such as liquid crystal display (LCD), organic light emitting diode (OLED), solar cells and so on. One of the most popular materials for TCO is so far indium tin oxide (ITO), which has low sheet resistance and high optical transmittances when it has crystalline structure. The main obstacle of obtaining crystalline ITO on flexible polyethylene terephthalate (PET) film is high crystallization temperature around 250 °C, at which the PET film cannot withstand. In addition, crystalline ITO is mechanically brittle, which makes it difficult to apply on flexible devices. In this study, flexible and crystallized ITO thin films were successfully obtained on PET films with single-layered graphene as a platform. To overcome the limitations of applying PET film as an ITO film support, single-layer graphene was employed as a robust support for ITO crystallization. The crystallized ITO (c-ITO)/graphene/PET electrode was successfully prepared with reasonable sheet resistance of ~45 ohm sq-1 and high transmittance of about 90% at 550 nm wavelength. The prepared flexible transparent c ITO/graphene/PET electrode was applied as the anode in a bulk heterojunction polymer solar cell (PSC) to evaluate its performance, which was comparable with that of the commonly used c-ITO/glass electrode. These results represent important progress in the fabrication of flexible transparent electrodes for future optoelectronics applications.

N.4.3
17:15
Authors : C. Greaves, B.P. de Laune, F.J. Berry, M.J. Whitaker, C.E. Johnson, H-Y. Hah, J.A. Johnson, D.E. Brown
Affiliations : University of Birmingham, UK; University of Birmingham, UK; University of Birmingham, UK; University of Birmingham, UK; University of Tennessee Space Institute,USA; University of Tennessee Space Institute,USA; University of Tennessee Space Institute,USA; Northern Illinois University, USA.

Resume : The tetragonal structure of FeSb2O4 comprises chains of edge-linked FeO6 octahedra which are separated by one-dimensional channels which lie parallel to the c-axis. We have shown that this material (and related materials that also contain some Fe2+ cations) can undergo topotactic oxidations at low temperatures (typically 250-350 deg C) in air or fluorine gas. Oxide/fluoride anions enter the channels and bond to antimony ions that form the channel walls; charge balance involves oxidation of either Fe2+ or Sb3+ ions. In this presentation, we discuss the structures of the anion-excess phases (derived primarily from neutron diffraction and Mossbauer spectroscopy) and rationalise the structural differences that are found between the interstitial oxide and fluoride materials. These differences relate to the bonding characteristics of Sb-O and Sb-F bonds, and are also responsible for a significant change to the mechanism for balancing the charge on the interstitial anions. We also report the changes to the low temperature magnetic order (neutron diffraction) that occurs as a result of these topotactic oxidations and explain these changes by considering how the chemistry affects the magnetic exchange interactions. In-situ electronic conductivity measurements (4-probe DC) performed during oxidation in air reveal that the reaction is very rapid at about 350 deg C and enhances the conductivity.

N.4.4
 
Poster Session I : ---
17:30
Authors : A.A. Prokhorov1, L.F. Chernush2, V. Babin3, M. Buryi3, D. Savchenko1, J. Lan?ok1, M. Nikl3, A.D. Prokhorov2
Affiliations : 1 Institute of Physics AS CR, Na Slovance 2, 18221 Prague, Czech Republic 2 A.A. Galkin Donetsk Physico-Technical Institute, R. Luxembourg 72, 83114 Donetsk, Ukraine 3 Institute of Physics AS CR, Cukrovarnicka 10, 16200 Prague, Czech Republic

Resume : Studied the X-ray irradiated EuAl3(BO3)4 single crystals by means of luminescence and electron paramagnetic resonance (EPR) spectroscopy. It was found that the X-ray irradiation modifies the color of the EuAl3(BO3)4 crystal and leads to the formation of a stable Eu2+ centers from the Eu3+ centers located in a host matrix. Annealing of the crystal at 600 C0 leads to the restoration of the original colour and the disappearance of Eu2+ centers. The EPR and luminescence spectra of the Eu2+ ion were studied in a wide temperature range. The angular dependence of Eu2+ EPR spectra is described by an axial spin Hamiltonian characterized by the spin of S=7/2 with the following parameters: gz=gx=1.991(1); b20=-267,86(16)*10-4cm-1; b40=-4,20(8)* 10-4cm-1; b60=0,37(13)* 10-4cm-1; A(151)= 31,4(3)* 10-4cm-1; A(153)= 13,9(3)* 10-4cm-1. Based on the comparison of spin Hamiltonian parameters of Eu2+ and Gd3+ ions, it was concluded that Eu2+ ion located at the Eu3+ site in the EuAl3(BO3)4 crystal lattice. Within the framework of the superposition model, the distortions introduced to the local environment by the Eu2+ and Gd3+ ions were analyzed. In the luminescence spectra, the bands associated with the Eu2+ and Eu3+ ions are detected. The photoluminescence decay kinetics of Eu3+-related emission (614 nm) has a single-exponential character, whereas the Eu2+-related band (323 nm) possess more complicated decay kinetics behaviour that may point to the Eu2+ excited state ionization and its delayed recombination.

N.4.5
17:30
Authors : DongWoong Choi (1)(2), KwangLeong Choy (1)
Affiliations : (1) UCL Institute for Materials Discovery; (2) Department of Chemistry, University College London

Resume : This research aimed to establish the mechanisms of SiO2/ZrO2 (SSZ) by electrochemical study and to analyze the effect of different Si/Zr molar ratios on novel anode material SSZ. The SSZ electrodes delivered a superior capacity when the molar ratio of Si/Zr was increased from 0.5, 1 to 2. The specific capacity of 2-SSZ was much higher than that of 0.5- or 1-SSZ. The 2-SSZ electrode also had superior cycling performance. This could be due to the formation of ZrSi2 by 2-SSZ which would provide more effective reactivity with Li-ions intercalation and deintercalation upon Li-ions diffusion than that of Zr2Si or Zr5Si3 from 0.5-SSZ or ZrSi from 1-SSZ. This result indicated that ZrSi2 increased the possible reaction area for the guest species (lithium ions) at the empty site in the host materials. It could provide a large space to accommodate volume expansions, and it was supportive by maintaining the lattice constant and reducing the ratio of the structural distortion. In addition, 2-SSZ structure consisted of a majorly amorphous structure with a crystalline structure related to the Zr-O-Si bond. Such combined structure was advantageous in providing a good capacity through amorphous structure and such efficient pathway for electron transport and little pulverization through the crystalline structure. With such benefits, the drastic volume expansion was reduced during repeated cycles, which led to the enhanced reversible capacity and the cyclability.

N.4.6
17:30
Authors : Ismail Cihan KAYA (1),(2), Seckin AKIN (2),(3), Savas SONMEZOGLU (2),(3), Hasan AKYILDIZ (1)
Affiliations : (1) Department of Metallurgical and Materials Engineering, Selcuk University, Konya, Turkey; (2) Nanotechnology R&D Laboratory, Karamanoglu Mehmetbey University, Karaman, Turkey; (3) Department of Metallurgical and Materials Engineering, Karamanoglu Mehmetbey University, Karaman, Turkey.

Resume : Composite nanofibers were prepared from homogeneously mixed copper chloride, chromium nitrate, magnesium nitrate and polyvinylpyrrolidone solution by electrospinning and were subsequently heat treated under isochronal and isothermal annealing conditions. In the isochronal experiments, CuCrO2 formation began at 500 ºC. Annealing at 700 ºC yielded single-phase, highly porous CuCrO2 nanofibers accompanied by the formation of large quasi-hexagonal grains. In contrast, isothermal annealing at 700 ºC resulted in the formation of phase-pure CuCrO2 nanofibers with belt-like morphology and relatively higher density. A substantial decrease was observed in the size and number of plate-like grains in these nanofibers. Therefore, all compositions were produced under isothermal conditions with flowing high purity nitrogen or argon gas atmosphere. X-ray diffraction study showed that the solubility limit was around 3 at.% for Mg-dopant and beyond this concentration the formation of MgO phase was observed. X-ray photoelectron spectroscopy examinations reveal that the oxidation states of Cu, Cr and Mg ions were 1, 3 and, 2, respectively in CuCrO2 nanofibers up to 3 at.% Mg doping. Cu 2 formation was detected for 5 at.% doping level. According to SEM observations the average width of the nanofibers were in the range of 100-150 nm and typical length for the continuous nanofibers reached almost to a few cm in a mat structure. Further, electron microscopy images showed that the final fiber morphology highly depend on the preparation of the electro-spinning solution and the relative amount of the precursors. Electrical and optical characterizations demonstrated that the optoelectronic properties of the obtained nanofibers are in well accordance with the values reported in literature. In addition, pure and Mg-doped CuCrO2 nanofibers were used as photocathode in p-DSSCs. The highest efficient cell was achieved with CuCrO2 photocathode doped with 3 at.% Mg. This p-DSSC exhibit photoelectric conversion efficiency of 0.035 %. Finally, the study showed that pure and doped CuCrO2 can be produced via the electrospinning process and obtained nanofibers are promising p-type semiconductor material for a variety of applications such as low cost and high efficient p-DSSCs. Support for this work was provided by TUBITAK MAG (Project no 214M410) which we gratefully acknowledge.

N.4.7
17:30
Authors : Murali Bissannagari, Jihoon Kim
Affiliations : Division of Advanced Materials and Engineering, Kongju National University

Resume : Despite the materials performances being superior to those of organic materials, inorganic materials are typically excluded for use in flexible and deformable electronic systems because of their rigid nature and the requirement for high processing temperature. This work presents a novel method of utilizing rigid NiZn-ferrite films in a flexible platform and offers an opportunity to realize a flexible wireless power transfer (WPT) module. Inkjet printing was introduced in this study since it can coat NiZn-ferrite films as well as pattern inductor coils for WPTs. A thermochemically inert buffer layer was selected based on a thermodynamic analysis and was introduced as a buffer layer for the NiZn-ferrite to prevent chemical reaction between the ferrite film and the substrate and ensure that the ferrite film can be easily separated from the substrate during a high-temperature sintering process. A Ag-inductor coil was printed on the NiZn-ferrite layer, and then the entire layer was embedded into polydimethylsiloxane, which renders the WPT module flexible. The flexibility of the WPT module was characterized by a bending test, and the structural and magnetic properties were also investigated. The performance of the flexible WPT module was demonstrated by transmitting wireless power to a light emitting diode.

N.4.8
17:30
Authors : Öznur KÜÇÜK, Seda TEBER, ?smail Cihan KAYA, Volkan KALEM, Hasan AKYILDIZ
Affiliations : Department of Metallurgical and Materials Engineering, Selçuk University, Konya, Turkey

Resume : BaTiO3 is an important material in the electronics industry, particularly because of its high dielectric constant and ferroelectric properties. In addition, perovskite-type BaTiO3 oxide photocatalysts have also drawn attention for degradation of organic chemicals in waste water due to its unique properties. Structural defects such as metal cation or anion vacancies resulting from the processing route or band bending nature of ferroelectric ceramic promote separation of charge carriers thus enhance the photocatalytic performance. Only the tetragonal crystal structure of BaTiO3 exhibits ferroelectric property and synthesis of barium titanate ceramic with this symmetry in nano-scale is of importance in a variety of applications. Targeting the tetragonal phase; we have synthesized BaTiO3 nanoparticles (dav ?100 nm) by conventional hydrothermal method using electrospun TiO2 fibers (tetragonal, dav ?155 nm) as a template precursor. Precipitates were obtained under basic conditions at 230 °C after 96 h of hydrothermal transformation. XRD, XPS and Raman spectroscopy measurements were revealed the formation of BaTiO3 with tetragonal crystal structure. Photocatalytic activity of tetragonal BaTiO3 nanoparticles were investigated via the decolorization of 100 mL methylene blue dye aqueous solutions (10 mg/L) under UV-A (? ? 354 nm) and visible light irradiation with 50 mg of catalyst loading. It was found that the tetragonal BaTiO3 nanoparticles had shown higher catalytic efficiency under UV-A irradiation. 65% of the dye was degraded under UV light in 6 h whereas the degradation amount was only 45% under visible light for the same duration. The linear nature of the obtained kinetic plots indicated that the degradation follows pseudo first-order kinetics. The calculated rate constant and half life values were 1.6 and 2.3 times higher, respectively, for degradation under UV-A irradiation compared to visible light experiments. Electrical properties were investigated using sintered pellets. The pellets were sintered at 1175, 1200 and 1250 °C for 5 h under air atmosphere. The highest dielectric constant and lowest loss factor at 1 MHz and room temperature were obtained as 3162 and 15x10-3 respectively, for the sample sintered at 1200 °C. Finally, the study showed that the TiO2 fibers can be used as a precursor template for the production of nano-scale BaTiO3 particles suitable for various applications such as photocatalysis, capacitor, and etc.

N.4.9
17:30
Authors : Kanako Kawaguchi (1), Yoshikazu Suzuki (2), Tomoyo Goto (3), Sung Hun Cho (3), Tohru Sekino (3)
Affiliations : (1) Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki, Japan. (2) Faculty of Pure and Applied Sciences, University of Tsukuba, Ibaraki, Japan. (3) The Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan.

Resume : Calcium hexaluminate (CaAl12O19 or CA6) with magnetoplumbite structure is the most alumina-rich stable intermediate compound of the CaO-Al2O3 system [1]. CA6 has excellent properties, e.g. high melting point, refractoriness, good thermal stability, and low thermal conductivity by its unique crystal structure and anisotropic plate-like morphology. Porous CA6 ceramics are promising materials as filters, catalysts supports and refractories under a severe environment such as under a high temperature or corrosive atmosphere.In this study, we produced porous CA6 ceramics by reactive sintering with controlled microstructure by changing alumina source and LiF doping. ?-alumina powder, ?-alumina powder and two-type boemite powders with different particle size (0.08 ?m, 0.7?m) as Al2O3 source and CaCO3 powder as CaO source were used as the starting materials. LiF powder was used as a mineralizer. Each Al2O3 source and CaO source were wet-ball milled for 24 h with/without LiF powder (0.5 wt. % of starting materials). The mixed slurries were vacuum dried and put into oven at 80 ºC for 1 night. The dried powders were sieved through a 150-mesh screen. The mixed powders were uniaxially pressed at 12 MPa to green compacts. The green compacts and the mixed powders (without pressing) were sintered in air at 1500 ºC-1600 ºC for 3 h to obtain CA6 pellets and powders. The crystalline phases of obtained samples were examined by X-ray diffraction, and the microstructures of pellets were observed by scanning electron microscopy. [1] R. W. Nurse, J. H. Welch and A. J. Majumdar, Trans. Br. Ceram. Soc., 64 (1965) 409-418

N.4.10
17:30
Authors : Sungmin Woo< sup>1,2< /sup>, Sang A Lee< sup>1< /sup>, Soohyeon Shin< sup>1< /sup>, Hyeona Mun< sup>3< /sup>, Young Gwan Choi< sup>4< /sup>, Chan June Zhung< sup>4< /sup>, Morgane Lacotte< sup>5< /sup>, Adrian David< sup>5< /sup>, Wilfrid Prellier< sup>5< /sup>, Jong Seok Lee< sup>4< /sup>, Sung Wng Kim< sup>3< /sup>, Tuson Park< sup>1< /sup>, Won Nam Kang< sup>1< /sup>, Woo Seok Choi< sup>1*< /sup>
Affiliations : < sup>1< /sup>Department of Physics, Sungkyunkwan University, Suwon, 16419, Korea; < sup>2< /sup>Center for Integrated Nanostructure Physics, Institute for Basic Science, Suwon, 16419, Korea; < sup>3< /sup>Department of Energy Sciences, Sungkyunkwan University, Suwon 16419, Korea; < sup>4< /sup>Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 61005, Korea; < sup>5< /sup>Laboratorie CRISMAT, CNRS UMR 6508, ENSICAEN, Normandie Universite, 6 Bd Marechal Juin, F-14050 Caen Cedex 4, France

Resume : Various physical properties of transition metal oxide (TMO) thin films can be tailored by introducing elemental vacancies, epitaxial strain, and/or dimensional effect. In addition, structural defect and strain presence in macroscopic grain boundaries can also modify electrical, magnetic, and thermal properties of the poly-crystalline solids. In this research, we focus on the modifications of magnetic and thermoelectric properties, i.e., ferromagnetic ordering, and thermal conductivity by fabricating single- and poly-crystalline epitaxial SrRuO< sub>3< /sub> thin films using the pulsed laser epitaxy (PLE). The reduced compressive strain due to coalescene at the grain boundaries influence inter atomic distance, resulting enhancement of the ferromagnetic ordering. On the other hand, since epitaxial poly-crystalline thin films are composed of various grains oriented to different directions, the structural variation due to grain boundaries can reduces the thermal conductivity and produce comparable thermoelectric efficiency (ZT) compare to single-crystalline thin film.

N.4.11
17:30
Authors : D. Kotsikau1, A. Eroma1, E. Korobko2, Z. Novikova2, V. Natarov1, V. Pankov1
Affiliations : 1. Department of Physical Chemistry, Belarusian State University, Belarus; 2. A.V. Luikov Heat and Mass Transfer Institute of The National Academy of Sciences of Belarus

Resume : Magnetorheological fluids (MRF) based on micro-sized carbonyl iron (CI) in synthetic oil are widely used as dampers and polishing systems in mechanical engineering, military and defense, optics, aerospace and other applications. Ferrimagnetic oxides like ?-Fe2O3, Fe3O4 and metal ferrites are promising materials as modifying agents for MRF. They could substantially improve the magnetorheological and sedimentation parameters of MRF. Rod-like magnetite (Fe3O4) particles were prepared by a slow oxidation Fe(OH)2 suspension with KClO3 to produce rod-like ?-FeOOH powder. Then the powder was reduced to Fe3O4 oxide by exposing to hydrogen at 455°C for 4 h. In order to prepare Zn-doped magnetite, a mixed Zn,Fe(OH)2 hydroxide was precipitated. The Zn content varied from 0 to 15 mol. % in relation to Fe. Well-crystalline particles with a spinel-type structure and a size of 50×500 nm were obtained at Zn concentration from 0 to 7 mol. %. Pure magnetite possesses a high magnetization (123 emu/g at 2 T) and noticeable coercivity (~10 Oe). Zn addition was used to reduce the coercivity for high-frequency applications of MRF. The best Zn-doped magnetite composition corresponded to 3 mol.% of Zn, where the magnetization was still high (94 emu/g), and the coercivity dropped to 6 Oe. The magnetorheological effectiveness of a MRF with the additive of the prepared Zn-Fe3O4 powder (15 wt. %) increased up to 30 % as compared to the pure MRF.

N.4.12
17:30
Authors : S. Koussi-Daoud, F. Odobel, T. Pauporté
Affiliations : Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris (IRCP), 11 rue P. et M. Curie, F-75005 Paris, France. CEISAM-UMR6230, Faculté des Sciences et des Techniques de Nantes, BP 92208 2, rue de la Houssinière, F-44322 NANTES Cedex 3, France.

Resume : Solvent engineering for the electrochemical preparation of porous, thick and adherent nickel oxide layers is investigated. The deposition of this oxide is studied in the pure aprotic dimethyl sulfoxide (DMSO) medium and in DMSO/water mixtures by cathodic reduction of nickel nitrate precursor. In pure DMSO, the as-grown layers were a mixture of directly obtained NiO and of metallic nickel. On the other hand, in the presence of water, beta-Ni(OH)2 and Ni° mixed layers were formed. Adding water is shown to increase the deposition current density and the layer coverage. After annealing at 450°C, for pure DMSO, the layers were made of NiO and contained some core Ni°. A sufficient electrochemical overvoltage is required for well-covering the substrate. We show that adding water in the bath, even at a low percentage, results in annealed layers made of NiO with NiOOH and core Ni° which part increases with the bath water content. Interestingly, mesoporous layers were formed for pure DMSO medium and for DMSO/2%H2O medium after annealing. DMSO is entrapped in the deposited material and acts as a blowing agent releasing the pores after annealing at a sufficiently high temperature. Some S remained on the surface. These solvent templated electrodeposited (STE) layers have been used in p-type dye-sensitized solar cells (p-DSSCs) after sensitization by the P1 dye. For high water content (25 vol.%), the electrodeposited layers were non-porous.

N.4.13
17:30
Authors : Sang Jin Lee1,2, Yekyung Kim1, Jin Woo Seo1, Hyeongkeun Kim1, Sahn Nahm2, Seung Ho Han1,*
Affiliations : 1Electronic Convergence Materials & Device Research Center, Korea Electronics Technology Institute, Gyeonggi-do 13509 Korea; 2Department of Materials Science and Engineering, Korea University, Seoul 02841 Korea

Resume : Electrochromic materials, which can reversibly change their optical properties under electric field, have attracted in various applications such as smart windows, optical displays, rear-view mirrors, and others. The nickel oxide (NiO) and tungsten oxide (WO3) are the most popular electrochromic materials of anodic and cathodic coloration, respectively. In an electrochromic device, NiO is generally used as a counter electrode with enhancing coloration efficiency of whole device with a pair of WO3, which mainly determines the efficiency of coloration and decoloration of whole device. However, NiO films suffer from severe charge density degradation during electrochemical reaction with a lithium-conducting electrolyte, which can reduce the device lifetime. In this study, the effect of tungsten doping on the cycling stability of electrochromic devices for NiO films was investigated. The structural, optical and electrochemical properties of the W-doped NiO films were demonstrated by X-ray diffraction, scanning electron microscopy, cyclic voltammetry, transmittance monitoring, etc. Also, the electrochemical and cyclic properties of electrochromic full-cell was determined.

N.4.14
17:30
Authors : Ying-Hsuan Chen, Andreas Erbe
Affiliations : Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH; Department of Materials Science and Engineering, NTNU, Norwegian University of Science and Technology

Resume : 2-Mercaptobenzothiazole (MBT) is known as one of the most effective corrosion inhibitors of copper for 40 years. During the inhibition process, MBT is supposed to react with copper forming a passivating layer (CuMBT complex) to prevent further corrosion [1]. The complex electrochemical and chemical processes between copper, electrolyte, copper oxides, and the inhibitor films are not fully understood, in particular, why the passivating layer is so stable and so protective. In this work, this mechanism was investigated by in situ infrared (IR) spectroscopy, in situ Raman spectroscopy and in situ UV/VIS spectroscopic ellipsometry, coupled with electrochemical experiments. The attenuated total reflection (ATR) technique was applied in IR spectroscopy to study MBT during electrochemical processes at the solid/liquid interface [2]. The temporal evolution of IR spectra at open circuit potential showed a rearrangement of MBT at the interface. Interfacial structure was also dependent on the electrode potential. In Raman spectra, the red shift of band at 1400 cm-1 at low electrode potential showed a difference between surface species and bulk species of CuMBT. The potential-dependent increase of thickness, which was obtained from ellipsometric spectra, indicated the formation of a CuMBT complex layer. Besides, the inhibition of oxide formation was examined in this work as well. It was shown that after the copper surface was treated with MBT solution, the formation of copper oxide was inhibited because of the disappearance of oxide related peak in Raman spectra. Based on these results, the final goal is to engineer molecular structures of corrosion inhibitors based on their reactivity, their tendency to adsorb on the metal and their tendency to passivate a surface.

N.4.15
17:30
Authors : D. Braun, L. von Helden, M. Schmidbauer, Y. Dai, R. Wördenweber and J. Schwarzkopf
Affiliations : Leibniz Institute for Crystal Growth, D-12489 Berlin, Germany; Leibniz Institute for Crystal Growth, D-12489 Berlin, Germany; Leibniz Institute for Crystal Growth, D-12489 Berlin, Germany; Peter Grünberg Institute (PGI-8), Forschungszentrum Jülich, D-52425 Jülich, Germany; Peter Grünberg Institute (PGI-8), Forschungszentrum Jülich, D-52425 Jülich, Germany; Leibniz Institute for Crystal Growth, D-12489 Berlin, Germany

Resume : One pathway to induce enhanced or even novel functionalities is the epitaxial growth of strained thin films on lattice mismatched substrates. Such a strain engineering in ferroelectrics can be performed on the basis of a strain-phase diagram and the linear elasticity theory. In this contribution, we present two different examples of strained lead-free KxNa1-xNbO3 films grown on rare earth scandate substrates by metal-organic chemical vapor deposition technique yielding different possible applications. First, K0.7Na0.3NbO3 films on (110) TbScO3 exhibit highly periodic, monoclinic Mc stripe domains elongated over microns. Processed as SAW device, a K0.7Na0.3NbO3 film of 45 nm thickness revealed the propagation of surface acoustic waves ? 1st and 3rd harmonic ? occurring exclusively along the monoclinic shearing directions. Moreover, the thin film yields an excellent signal-to-noise ratio. Secondly, K0.9Na0.1NbO3 on (110) NdScO3 is characterized by equal strain energy densities for two different pseudocubic unit cell orientations. As a result of competing electrical polarizations, a ferroelectric herringbone pattern with alternatingly arranged, monoclinic a1a2/Mc domains evolves. Due to polarization discontinuities at each domain wall promising longitudinal piezoelectric coefficients occur. Moreover, the monoclinic symmetry enables a tunable domain wall arrangement and thus an additional degree of freedom for domain engineering making it interesting for e.g. energy harvesters.

N.4.16
17:30
Authors : G.M. Kaleva, E.D. Politova, A.V. Mosunov, and N.V. Sadovskaya
Affiliations : L.Ya. Karpov Institute of Physical Chemistry, Vorontsovo Pole, 10, 3, 105064, Moscow

Resume : Effect of low-melting additives on the structure, microstructure and electroconductivity of modified lanthanum gallate ceramics as perspective electrolytes for high temperature solid oxide fuel cells G.M. Kaleva, E.D. Politova, A.V. Mosunov, and N.V. Sadovskaya L.Ya. Karpov Institute of Physical Chemistry, Vorontsovo Pole, 10, 3, 105064, Moscow e-mail:politova@cc.nifhi.ac.ru The materials based on lanthanum gallate LaGaO3 such as La0.9Sr0.1Ga0.8Mg0.2O3-y (LSGM) are considered among the most perspective electrolyte materials for the intermediate temperatures solid oxide fuel cells (IT-SOFS) due to its stability and high ion conductivity in the wide range of the partial pressure of oxygen (1 ? 10-22 atm.) and insignificant electronic conductivity. One of the most effective approaches to optimizing the functional characteristics of ceramic materials is to introduce low-melting additives. In this work ceramic samples in the system (La0.8Sr0.2){[Ga0.8-x(Ge0.5Mg0.5)x]Mg0.2}O3-d (x=0 ÷ 0.8), additionally modified with low-melting additives of bismuth oxide and lithium fluoride (5 wt. %) were prepared by the solid state reaction method. The effect of additives on the phase formation, crystal structure, microstructure and electric conductivity was investigated using the X-ray diffraction, Scanning Electron Microscopy and dielectric spectroscopy methods. According to the X-ray diffraction data, perovskite structure phase was formed in the samples with x = 0 ÷ 0.6. These compounds are characterized by the pseudocubic structure. The additives were shown to lower the sintering temperature of the ceramics due to the mechanism of liquid phase sintering, raise the density of the samples, maintain their stoichiometry and optimize microstructure. The temperature dependences of the total electric conductivity of ceramics confirmed its high values at temperatures near 1000 K, which suggests the possibility of using them as promising electrolyte materials for IT-SOFSs. Acknowledgments: This work was supported by the Russian Foundation for Basic Research, project no. 16-03-00581.

N.4.17
17:30
Authors : S. Garroni1,2*, N. Senes3, A. Iacomini3, L. Nuvoli3, S. Enzo3, G. Mulas3, S. Cuesta-Lopez1,2
Affiliations : 11International Research Centre in Critical Raw Materials-ICCRAM, University of Burgos, Plaza Misael Banuelos s/n, 09001 Burgos, Spain 2Advanced Materials, Nuclear Technology and Applied Bio/Nanotechnology. Consolidated Research Unit UIC-154. Castilla y Leon. Spain. University of Burgos. Hospital del Rey s/n, 09001 Burgos, Spain 3Department of Chemistry and Pharmacy, University of Sassari and INSTM, Via Vienna 2, I-07100 Sassari, Italy

Resume : Ultrasonic imaging system is a non-invasive medical imaging technique that has become one of the most widely used diagnostic tools in modern medicine for detecting prenatal anomalies and deep screening of biological tissues [1]. The ultrasound transducer in the probe is generally made of a piezoelectric ceramic material such as lead zirconate titanate (PZT). Among several class of piezo materials, the perovskite Lead Zirconate Titanate (PZT), with the general formula Pb(ZrxTi1-x)O3 x = 0.52?0.55, dominates in the market for piezoceramic components due to their excellent piezoelectric properties and higher dielectric constant [2, 3]. New challenges regard the opportunity to synthesize PZT ceramics with highly 3D interconnected pores and high porosity (> 80%) with the aim to significantly improve the HFOM parameters while maintaining high piezoelectric capacity. Important issues, such as mechanical stability, wettability and poor electric performance remain still unresolved, and represent the main barriers to a rapid commercialization in the international market of the porous PZT ceramics for ultrasonic transducer applications. Furthermore, the presence of a lead-based material can be considered a critical issue for device working in contact with biological tissues. During the last decades, significant attention has been paid to the search of lead-free piezoceramics with properties, such as high piezoelectric coef?cient and electromechanical coupling factor, comparable to lead-based piezoelectrics. Among these lead-free candidates, in the past 10 years, KxNa1-xNbO3 (KNN) has become one of the most investigated lead-free piezoelectric system due its large d33 (?390-490 pC/N) and relatively high Curie temperatures, TC, (?217-304 °C), coupled with its high chemical inertia and compatibility with human tissue, which made it optimal for medical devices [4]. Recently, two main preparation procedures are emerged for the KNN synthesis, which involves the solid-state reaction routes (SSR) and wet chemistry routes such as sol-gel, solvothermal, Pechini, hydrothermal, etc. If the SSR route has been considered a fast and solvent-free procedure to produce KNN pellets, the exploitation of the wet-chemistry methods allowed to significantly improve the control of the stoichiometry in the final system. This contribution aims at providing an overview on the most successful procedures for synthesizing high performing KNN-based systems promising for biomedical applications. Additionally, the most recent and appealing results obtained in the framework of the European project, Nanopiezoeletrics, will be discussed. Particular emphasis will be addressed to the preparation of the KNN systems via wet chemistry and solid state, their structural properties and the opportunity to decrease their sintering temperatures. The positive effect of new dopants, mainly nanocellulose and magnesium niobate, on the microstructural and electrical properties of the lead-free ceramics, will be also presented. Reference: [1]. J. Holterman, P. Groen, an introduction to Piezoelectric Materials and Applications, edited by Stichting Applied Piezo, 1st edn (Apeldoorn, 2013). [2]. Market Report, Global Piezoelectric Device Market, May, 2014, Publisher: Acmite Market Intelligence, Language: English, Pages: 543. [3]. K. Boumchedda et al., J. Eur.Ceram.Soc., 27, 4169-71 (2007). [4]. Y. Saito, et al., Nature, 432, 84-87 (2004).

N.4.18
17:30
Authors : Tanja Pe?nik, Barbara Mali?
Affiliations : Electronic Ceramics Department, Jo?ef Stefan Institute, Jamova cesta 39, 1000 Ljubljana, Slovenia

Resume : Antiferroelectric (AFE) materials possess low dielectric losses, low coercive field, low remnant polarization and high energy density, which make them suitable for applications such as high-energy storage capacitors [1,2]. Much of the work has been done on lead-containing perovskite representatives such as PbZrO3 but due to the growing environmental concerns towards the use of hazardous lead also lead-free AFEs attracted much attention [3]. Shimizu and coworkers proposed a novel family of AFE materials based on NaNbO3, i.e. xCaZrO3-(1-x)NaNbO3 (0.1?x?0.10), where the presence of AFE domains was confirmed by Transmission Electron Microscopy in ceramics for compositions with x=0.04 and 0.05 [4]. Due to the increased demands for miniaturization of electronic devices AFE thin films are an interesting option. We report in this contribution on the phase composition, microstructure and electrical properties of 0.05CaZrO3-0.95NaNbO3 (CNZN) thin films prepared by Chemical Solution Deposition. The CNZN films were prepared from acetate-nitrate-alkoxide based solutions, with 2-methoxyethanol as the solvent. Niobium ethoxide and zirconium n-propoxide were stabilized with diethanolamine and acetic acid, respectively, in 1:2 volume ratios. The transition metal reagents, sodium acetate and calcium nitrate were mixed for 2 h at room temperature in inert atmosphere. The 0.2 M solution was deposited on platinized silicon substrates by spin-coating, dried at 150 °C and pyrolyzed at 300 °C. After repeating eight deposition-drying-pyrolysis steps the films were annealed in a rapid thermal annealing furnace at 600 °C and 625 °C for 5 min and 10 min in air. Cr/Au top electrodes with the diameter of 0.4 mm were deposited by magnetron sputtering. According to X-ray Diffraction analysis all films crystallized in pure perovskite phase. The Field-Emission Electron Microscope analysis revealed that the films are around 250 nm thick and their cross-section microstructures consist of fine grains with the average lateral grain size of around 30-50 nm with some intergranular porosity. The room-temperature dielectric permittivity of the CNZN films annealed at 600 °C for 10 min is 420, measured at 100 kHz and it increases to 530 with increasing the annealing temperature to 625 °C. The dielectric losses remain between 0.02 and 0.03 for all films. All CNZN films exhibit ferroelectric loops with remnant polarization and coercive field values around 4 µC/cm2 and 60 kV/cm, regardless the annealing temperature and time, respectively. The leakage current is between 2x10-6 and 2x10-7 A/cm2 measured at 200 kV/cm. In the contribution we also discuss the influence of manganese doping on low- and high-field dielectric properties of respective films. [1] K.M. Rabe, Antiferroelectricity in oxides: A reexamination, in: Functional Metal Oxides: New Science and Novel Applications, 2013, 221-244. [2] A. Chauhan et al., Materials 8 (2015), 8009?8031. [3] X. Tan et al., Journal of the American Ceramic Society 94/12 (2011), 4091-4107. [4] H. Shimizu et al., Dalton Transactions 44 (2015), 10763?10772.

N.4.19
17:30
Authors : Vitoria TOSCHI, Christine BOGICEVIC, Jean-Michel KIAT, Henri LAVILLE
Affiliations : Vitoria TOSCHI - Laboratoire Structures, propriétés, modélisation des solides, CentraleSupelec, Université Paris Saclay, France & Exxelia Technologies, France; Christine BOGICEVIC - Laboratoire Structures, propriétés, modélisation des solides, CentraleSupelec, Université Paris Saclay, France; Jean-Michel KIAT - Laboratoire Structures, propriétés, modélisation des solides, CentraleSupelec, Université Paris Saclay, France & Laboratoire Léon Brillouin, CE Saclay CNRS-UMR12, 91991 Gif-Sur-Yvette Cedex, France; Henri LAVILLE - Exxelia Technologies, France;

Resume : Design of materials for microelectronics with high temperature performances is an industrial issue of uttermost importance, since more and more new fields of applications require devices working at temperatures as high as 350°C. Among many examples are oil drilling, electronic control of car engines or of aircraft reactors, where devices are put closer and closer to heat sources to allow cost and size reduction. In this context, BaTiO3 (BT)-based materials traditionally used in the manufacture of multilayer ceramic capacitors (MLCC) become useless as their performances vanish at these high temperatures. Simple modifications of BT by cation doping allow to push the Curie temperatures towards higher but still insufficient values. Lead-based materials could reach a satisfactory level of performance, however, their uses as capacitors are restricted by RoHS and REACH regulations. Therefore, it is imperative to develop new materials to meet the expectations of electronics at high temperature. Among all possible candidates widely studied in literature, ceramics based on 0.94 Na0.5Bi0.5TiO3 ? 0.06 BaTiO3 (NBT-BT) are among the best candidates to reconcile both a high level of performances and an easy manufacture process [1]. This system is a solid solution of two different perovskites whose interesting compositions stand close to a morphotropic phase boundary, and exhibit improved properties compared to both end members. Indeed, NBT is a well-known relaxor ferroelectric compound with high Curie temperature (about 320°C) [2] whereas BT has a low Curie temperature (about 123°C). The resulting ceramics, with further combination of other dopants, originate materials with high permittivity and low losses within a large and elevated temperature range. Synthesis of NBT was performed using a conventional solid state method and optimized at each steps of the process under a large range of temperatures and different conditions, including annealing, ball milling, sintering under different atmosphere etc. In particular in order to reduce the volability of the sodium and the bismuth, sintering temperature was optimized to guarantee a high density, a high permittivity and low loss; compatibility of the ceramics with other materials involved in the MLCC building, such as the binder and the metallic ink, were tested as well. Dielectric and resistivity measurements were performed and associated to structural characterizations using X-ray diffraction, Raman diffusion and scanning electron microscopy. Using NBT-BT a further step will be achieved as several compositions of different systems will be obtained and characterized as well. During all the study peculiar attention was paid to the compatibility of the in-lab synthesis with the much more demanding industrial processes, not only in term of the methods but also in term of the resulting costs. Key words: Multilayer ceramic capacitors, MLCC, NBT, ferroelectricity, high temperatures. [1] Zeb A., Milne S. J. (2015). High temperature dielectric ceramics: a review of temperature-stable high-permittivity perovskites. Journal of Materials Science, 26, 9243?9255. [2] Mudinepalli1 V. R., Reddy N. R., Lin W., Kumar K.V. S., Murty B.S. (2015). Phase transitions of the ferroelectric Na0.5Bi0.5TiO3 by dielectric and internal friction measurements. Advanced Materials Letters, 6(1), 27 ? 32.

N.4.20
17:30
Authors : N. Senes1*, S. Garroni2,3, A. Iacomini1, L. Nuvoli1, S. Cuesta Lopez2,3, N. Domingo4, S. Enzo1, G. Mulas1.
Affiliations : 1Departament of Chemistry and Pharmacy, University of Sassari and INSTM, Via Vienna 2, I-07100 Sassari, Italy; 21International Research Centre in Critical Raw Materials-ICCRAM, University of Burgos, Plaza Misael Banuelos s/n, 09001 Burgos, Spain; 3Advanced Materials, Nuclear Technology and Applied Bio/Nanotechnology. Consolidated Research Unit UIC-154. Castilla y Leon. Spain. University of Burgos. Hospital del Rey s/n, 09001 Burgos, Spain; 4ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona), Spain;

Resume : In the last 30 years piezoceramic materials have captured significant attention in the scientist community thanks to their excellent properties and high performance in different technological application ranging from energy harvesting to ultrasonic transducer . In the recent decade, diverse classes of materials have been taken in consideration to replace the classical and most used PZT (PbZrTiO3, lead zirconate titanate). Considerable interest was in fact shifted to environmental friendly lead free-systems, which appear more suitable for devices working in contact with biological tissues. Among them, KNN (K,NaNbO3, potassium sodium niobate) composed by ferroelectric KNbO3 and antiferroelectric NaNbO3 phases, represents a good option due its large piezoelectric constant (d33 ~ 200-400 pC/N) associated with a high Curie Temperature (TC ~ 400°C) and no toxicity. However, this system suffers from different disadvantages, for example: pure ceramic KNN are difficult to be obtained by conventional solid-state method due to the high volatility of the alkali components and instability of the crystalline phase at high temperatures. In addition, the poor packing property as a consequence of the cubic-shaped KNN grains, implies a low value of the material density . The piezoelectric activity is closely related to chemical and physical properties that can be modified employing appropriate strategies during synthesis. Taking in consideration this important point, it emerges that sol gel routes could be useful for overcoming some of the abovementioned issues occurred in the system . In this context, the contribution of this work aims to report and discuss some of the most relevant results, achieved in the last year, in the synthesis of the KNN-based ceramics prepared by facile sol-gel routes. In particular, the emphasis will be put on the comparison of two approaches with the respective structural, morphological and performance characterizations of the obtained samples. The first one has allowed to obtain dense powders, using cheap and no toxic precursors and successfully monitoring phase, structure and composition under low temperature during the steps of synthesis. The second method has permitted to obtain matrices with high surface area, stability of the precursors solutions and porosity of the sample through soft template technique. Finally, it was possible to synthesize materials with good chemical stoichiometry, uniform doping and lower crystallization temperature. 1.Source: iRAP, Inc. (2013). Please cite this article as: Hong C-H, Kim H-P, Choi B-Y, Han H-S, Son JS, Ahn CW, Jo W, Lead-Free Piezoceramics - Where to Move on?, Journal of Materiomics (2016), doi: 10.1016/j.jmat.2015.12.002 2.Properties, D. (1954). K)Nb03t, 96(8). 3.Jaffe, B., Cook, W. R. Jr., Jaffe, H.; Piezoelectric Ceramics, Academic Press, London and New York (1971). 4.Chilibon, I., & Marat-Mendes, J. N. (2012). Ferroelectric ceramics by sol-gel methods and applications: A review. Journal of Sol-Gel Science and Technology, 64(3), 571?611. https://doi.org/10.1007/s10971-012-2891-7

N.4.21
17:30
Authors : Masashi Miyakawa, Mitsuru Nakata, Hiroshi Tsuji, Yoshihide Fujisaki, and Toshihiro Yamamoto
Affiliations : NHK Science & Technology Research Laboratories

Resume : Simple and inexpensive solution-processed oxide TFTs based on an amorphous metal oxide semiconductor such as In-Ga-Zn oxide (IGZO) have been widely researched. However, challenges remain for device applications due to low device performance. Compared with oxide TFTs fabricated using a conventional vacuum process, solution-processed oxide TFTs exhibit lower mobility and instability due to trap states originating from residual species [1,2]. High-temperature processing over 400 ºC is generally required for chemical conversions from the precursor to the oxide, but temperatures exceeding 300 °C are unfavorable for achieving low cost and process simplicity. Here, we report fluorine-doped IGZO:F TFTs fabricated by low-temperature solution processing at 300 ºC. A IGZO precursor with fluorine additives was synthesized to suppress the formation of residual species by taking advantage of the strong metal-fluorine bond energy. TFTs fabricated with conventional IGZO and with the IGZO:F precursor were fabricated and evaluated. The fluorine additives enhanced the mobility and reduced the Vth shift under positive bias stress tests compared to those of the undoped TFT. The mobilities of the IGZO and IGZO:F TFTs were 1.8 and 4.5 cm2/Vs, respectively. Thermal desorption analysis indicated that the fluorine additives are effective at decreasing the total content of residual species. Furthermore, the IGZO:F TFTs fabricated using the hydrogen injection and oxidation method, which is considered effective for film densification, exhibited a mobility of 7.0 cm2/Vs. We believe that the fluorine additive method will lead the development of high-performance solution-processed oxide TFTs for device applications. [1] M. Miyakawa et al., AIP Advances, 085016, (2016) [2] Kim et al. Jpn. J. Appl. Phys., 02BA02 (2014).

N.4.22
17:30
Authors : Sergyi Nizhankovskyi, Anatolii Kozlovskyi, Nazar Kovalenko, Olena Vovk, Sergyi Krivonogov, Oleh Vovk, Yuriy Siryk, Konstantin Kushnir
Affiliations : Institute for Single Crystals, STC ?Institute for Single Crystals?, National Academy of Sciences of Ukraine, Kharkiv, Ukraine

Resume : The lasers emitting in the eye safe IR spectral region 1.5 ? 1.7 ?m are of interest for use in the systems of laser location and ranging. The Er,Yb?codoped glasses were most often used as active media for lasing in this spectral range [1]. Nevertheless low damage threshold and thermo-mechanical properties limit their applicability in average and high power applications. This work focuses on the production of Er,Yb?codoped Y3Al5O12 (YAG) single-crystals grown for the first time by modified horizontal directional crystallization (HDCM) method [2] in carbon-containing environment and the characterization of their spectroscopic and lasing properties. The dimensions of grown crystals of Er,Yb :YAG (0,5 at % Er, 8 at. % Yb ) are 70×200×20 mm3. The crystallization processes were carried out in reducing atmosphere Ar (CO, H2). Analysis of the absorption and photoluminescence spectra in the spectral range of 190 ? 1600 nm showed that the main spectral lines correspond to optical transitions between the ground and excited states of Er3 and Yb3 ions. In optical spectra there were also the bands in UV region due to F-centers and Ti3 ion impurity, which decreased or disappeared completely after annealing in oxidizing atmosphere. In the prepared active elements 1.64 ?m lasing with pumping power threshold 2 W, corresponding to power density of 8 kW/cm2, was obtained. This result is comparable to modern literature data for crystals of Er,Yb:YAG. The applicability of the modified HDCM method to grow laser grade crystals of Er,Yb:YAG has been demonstrated. [1] E. Georgiou, O. Musset, J.P. Boquillon // Appl. Phys. B 70, 755?762 (2000) [2] S.V. Nizhankovskyi, A.V. Tan?ko, N.S. Sidelnikova, G.T. Adonkin // Crystal Res. and Tech. 50, Is. 3, 223-229 (2015).

N.4.23
17:30
Authors : L. Vradman1,2, J. Zana1,Y. Yevilevich1, E. Friedland2, R. Vidruk-Nehemya2 and M. Herskowitz2
Affiliations : 1Department of Chemistry, Nuclear Research Centre Negev, Beer-Sheva 84190, Israel 2Blechner Center for Industrial Catalysis and Process Development, Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel

Resume : La-based perovskites are an interesting class of oxides potentially applied in solid oxide fuel cells and catalysis. In the traditional synthesis methods, the formation of perovskite crystals occurs via a process in the solid phase, limiting the ability to control the product properties, especially morphology and crystal size. Molten salt offers a unique liquid medium for the perovskite formation potentially enhancing the control of its properties. However, in order to take the full advantage of molten salt synthesis, there is a need for deeper understanding of the mechanistic aspects and the factors affecting the perovskites formation process. In this presentation we will describe synthesis of pure phase LaMO3 (M=Co, Mn, Al) perovskites in molten NaCl-KCl, LiCl-KCl and KF-KCl eutectic mixtures at various temperatures (600-850°C) and reactant/salt ratios. The synthesis temperature has minor effect on the obtained perovskites crystal size for the given salt, while the salt type effect was much more pronounced yielding larger crystals in LiCl-KCl due to its low melting point. Heating the mixture of La- and M-precursors with the salt to the synthesis temperature yielded large La-perovskite crystals, while when La- and M-precursors were introduced to the molten salt heated to synthesis temperature, much smaller crystals were obtained. These results shed light on the mechanism of the perovskites formation in molten salts involving nucleation and crystal growth phenomena.

N.4.24
17:30
Authors : Takashi Ehara
Affiliations : Faculty of Human Studies, Ishinomaki Senshu University

Resume : CuGaO2 thin films were deposited on quartz glass substrates by sol?gel spin coating method using two combinations of Cu and Ga source. One is combination of Cu and Ga nitrate, and the other is Cu and Ga acetylacetonate. In each process, homogeneous and stable solutions were prepared by dissolving in 2-methoxyethanol, however, 2-aminoethanol was used as a chelating reagent in the case of acetylacetonate combination. Gel thin films were obtained after preheating the spin coated thin films at 200°C for 10 min and 500°C for 20 min after each coating. The films, after the deposition of the six layers, were annealed in nitrogen at temperatures of 800°C -1000°C. X-ray diffraction analysis revealed that the thin films prepared using metal nitrate that annealed at higher temperature than 900°C show that the films are c-axis grain orientation by peaks of (003) and (006). However, the films are thin yellow coloured at annealing temperature of 900°C or opaque white at 1000°C. In contrast, the films prepared using acetylacetonate shows non-c-axis oriented peaks (012) with significantly weak signal intensity. Instead, the films are significantly transparent compared with the films prepared by nitrates at annealing temperature of 800°C -1000°C.

N.4.25
17:30
Authors : A.V. Pashchenko 1,2, N.A. Liedienov 1, V.K. Prokopenko 1, V.A. Turchenko 1, 3, A.V. Voznyak 1, I.I. Makoed 4, V.P. Kladko 5, A.I. Gudimenko 5, D.D. Tatarchuk 6, Y.V. Didenko 6, A.T. Kozakov 7, I.V. Fesych 8
Affiliations : 1 Donetsk Institute for Physics and Engineering named after O. O. Galkin, NASU, 03028, Kyiv, Ukraine; 2 Donetsk National University of Economy and Trade named after Michael Tugan - Baranovsky, 50005, Kryvyi Rih, Ukraine; 3 Joint Institute for Nuclear Researches, 141980, Dubna, Russia; 4 Brest State University named after A. S. Pushkin, 224016, Brest, Belarus; 5 V.E. Lashkaryov Institute of Semiconductor Physics, NASU, 03028, Kyiv, Ukraine; 6 National Technical University of Ukraine ?Igor Sikorsky KPI?, 03056, Kyiv, Ukraine; 7 Scientific-Research Institute of Physics at Southern Federal University, 344194, Rostov-na-Donu, Russia; 8 Taras Shevchenko National University of Kyiv, 01030, Kyiv, Ukraine

Resume : The structure, structure defects, valence states of ions, microstructure and dielectric properties of the Bi1?xLaxFeO3-? multiferroics were investigated by X-ray diffraction, thermogravimetric, iodometric titration, SEM, XPS and dielectric spectroscopy methods. According to X-ray diffraction data, all samples with x = 0.1; 0.15; 0.2; 0.3 and 0.5 were single-phase with a rhombohedral R3c type of distortion. The lattice parameter decreases during isovalent substitution of Bi3+ for La3+ ions. On the basis of the established defect formation mechanism and the obtained experimental data, the molar formulas of a real perovskite structure have been determined. It was found out that the real structure contains variable valence Fe2+ and Fe3+ ions as well as point defects of the vacancy type. The presence of variable states of iron ions was confirmed by XPS spectroscopy. According to SEM data, the average crystallite size was ~ 1-5 ?m. At room temperature, all samples have anomalously high values of the relative permittivity ?'~ 10^5 and relatively small losses tan? ~ 1.3 at the frequency of f = 1 Hz, which values decrease to ?' ~ 100 and tan? ~ 0.4 with increase in the frequency to f = 1 MHz. The high values of ?' are explained by the charge accumulation on intercrystalline boundaries according to the Maxwell-Wagner phenomenon. It was established that an additional annealing of the samples leads to a decrease in microstrains and ?' as well as an increase in structure defects and tan?.

N.4.26
17:30
Authors : Yi Hu (1), Ping-Chun Shih (1), Chun-Chi Lin (1), Mazurkiewicz-Pawlicka Marta (2), Malolepszy Artur (2), Chung-Kwei Lin (3)
Affiliations : (1) Department of Materials Engineering, Tatung University,Taipei, Taiwan? (2) Chemical and Process Engineering ,Warsaw University of Technology, Warsaw, Poland; (3) School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan

Resume : Cuprous oxides are versatile metal oxides in the applications of many fields such as solar cells, photocatalysis, optoelectronics, electrochromic devices and sensors. Among these materials, copper oxide CuO is very promising. It is naturally a p-type semiconductor material with a band gap of about 1.5eV. Thin films of copper oxide have been previously fabricated by the sol?gel synthesis method, microwave-assisted hydrothermal, reactive DC sputtering and RF magnetron sputtering. In this work nanostructured Copper oxide thin films of Cu1-xLiXOy (x=0~0.100) were deposited on oxidized silicon substrates using e-beam vacuum evaporation at 100ºC substrate temperature and then annealed in air at varied temperatures from 400 ºC to 600 ºC for 2 hours. The influence of Li on the structural, optical and electrical properties was studied. The structural, electrical, and optical properties of the film are determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), four point probe and UV-visible spectroscopy. The thickness of the thin films is about 300nm and the thin films are composed of nanoparticles of about 20nm. The XRD analysis results of the thin films demonstrate that the single phase of CuO with high a crystalline structure. The sample with x=0.025 shows the lowest resistivity of 242 ?-cm and the maximum work function of 7.29eV as annealed at 600°C. The Optical band gap value varied between 1.4 eV and 1.7 eV. The absorbance and absorption coefficient are increased with increasing Li-doping in the CuO thin films.

N.4.27
17:30
Authors : Kensuke Kikuchi, Tomonari Furuya, Tsubasa Wada, Yasuhiro Yamamoto, Setsu Suzuki, Keiji Ishibashi
Affiliations : Kensuke Kikuchi, Tomonari Furuya, Tsubasa Wada;Graduate school of Science and Engineering, Hosei University Yasuhiro Yamamoto;Faculty of Science and Engineering, Hosei University Setsu Suzuki, Keiji Ishibashi;Comet Inc.

Resume : The compound oxide of CeO2 and SiO2 was deposited on p-type Si (100) substrates by MOCVD using Ce(OCEt2Me)4 at the substrate temperature of 350 °C for 30 min with the intermittent introduction of TEOS (TetraEthoxyOrthoSilicate) for 10 s every 3, 5, or 10 min. In XRD measurements, CeO2 peaks distinctly seen for the pure CeO2 films were suppressed to the trace level for CeO2-SiO2 films; the compound oxide film of CeO2 and SiO2 was essentially amorphous. From the XPS spectra, the average molar concentrations of SiO2 in the films with the introduction of TEOS for 10 sec every 3, 5, or 10 min were found to be 15%, 6% and 6%, respectively. Although TEOS was intermittently introduced during CeO2 deposition, the distribution of Si in the films was uniform. Moreover, cerium silicate formation in the film prepared with TEOS introduction was confirmed from Si2s and O1s spectra. The electrical properties were analyzed by C-V measurements using the Pt dot electrodes. The relative dielectric constant ranged between 16.6 and 21.6 which were larger than that the values of pure CeO2 films, around 8-12. These results suggest that in the CeO2-SiO2 compound films the low dielectric constant interfacial SiO2 layer formed in the case of pure CeO2 films was not generated.

N.4.28
17:30
Authors : Kota Yamaguchi, Takemi Takazawa, Kenta Kumagai, Setsu Suzuki, Keizi Ishibashi, Yamamoto Yamamoto
Affiliations : K. Yamaguchi, T. Takazawa, K. Kumagai; Graduate school of Science and Engineering, Hosei University Y. Yamamoto; Faculty of Science and Engineering, Hosei University S. Suzuki, K. Ishibashi; Comet Inc.

Resume : Mixed compound oxide films of Pr and Ce with various composition ratios were deposited on p-type Si (100) substrates by RF magnetron co-sputtering system equipped with ?2? metal Pr and sintered CeO2 cathodes in Ar + 10 % O2. Using the Pr cathode alone, Pr oxide did not deposited in front of Pr sputtering gun but did on the outskirts. When both cathodes were activated, the composition ratio of the mixture oxides varied according to the distance from the front of Pr to that of CeO2 sputtering gun, ranging from Pr oxide: Ce oxide = 64 %:36 % to 94 %: 6 %. The samples were annealed at 300, 500 and 800 °C for 30 min in a N2 atmosphere. In the case of pure Pr oxide, the XRD measurement revealed that the dominant diffraction line of the as-deposited film represented cubic PrO2, which remained up to 500 °C and that the phase transition to hexagonal Pr2O3 occurred at 800 °C. The XTEM observation revealed that the SiO2 layer formed at the interface between the film and the Si substrate in the as-deposited sample was scavenged during the post-annealing up to 500 °C. After annealing at 800 °C, the Pr oxide film had the three-layered structure from the interface; the Pr silicate layer, layer containing equally spaced Pr2O3 grains, the close columnar PrO2 layer. In the case of mixed oxides, the XRD and XTEM revealed that the silicate formation was inhibited as a result of obstruction of phase transition of PrO2 to hexagonal Pr2O3 by the presence of tenacious cubic CeO2.

N.4.29
17:30
Authors : Arij MARZOUKI, Christine BOGICEVIC, Pascale GEMEINER, Vincent LOYAU, Adel MEGRICHE, Brahim DKHIL
Affiliations : Arij MARZOUKIa,b, Christine BOGICEVICb, Pascale GEMEINERb, Vincent LOYAUc, Adel MEGRICHEa, Brahim DKHILb a. Université de Tunis El Manar, Faculté des Sciences de Tunis, UR11ES18 Unité de Recherche de Chimie Minérale Appliquée, 2092 Tunis, Tunisia. b. Laboratoire Structures, Propriétés et Modélisation des Solides, CentraleSupélec, CNRS-UMR8580, Université Paris-Saclay, 92295 Chatenay-Malabry, France. c. SATIE UMR 8029 CNRS, ENS Cachan, Université Paris-Saclay, 61, Avenue du Président Wilson, 94235 Cachan Cedex, France.

Resume : Multiferroic materials that simultaneously exhibit both polar and magnetic orders have attracted an ever-increasing interest driven by the ability to couple magnetic and electric properties which allow for instance tuning the magnetization using an external electric field instead of a magnetic one. Beyond the fascinating and challenging physics related to this coupling, magnetoelectric (ME) effect has many potential applications including room-temperature magnetic field sensors and electric current probes, microwave filters or ME recording read heads [1,2]. Since the ME response of single-phase magnetoelectric materials is too small for device applications, intensive experimental and theoretical studies were focused on multiferroic composites combining ferroelectric and ferromagnetic materials [3,4]. BiFeO3 (BFO) exhibits simultaneously both ferroelectricity (Tc~1103 K) and anti-ferromagnetism (TN~643 K) at room temperature which makes it a potential candidate in the field of information technology and optoelectronic devices [5,6]. Solid solutions such as BiFeO3-ABO3 perovskite-based materials have been investigated to minimize the high electric leakage of BiFeO3 keeping strong polarization and enhance the magnetization value in order to achieve stronger ME response. However, in such single-phase systems the ME properties remains rather poor while achieving a composite-like system might allow a better response. Usually, to avoid solid solution to be formed between two materials in a composite system, BFO of perovskite structure is associated for instance to spinel structure compounds such as CoFe2O4 because of the immiscibility of both structures. Here, to achieve improvement of the ME response, a composite using perovskite 1-perovskite 2 like system made of 50% of Co-doped BFO we optimized for its ME properties, and 50% of the well-known ferroelectric-piezoelectric Pb(Zr0.52Ti0.48Ti)O3 (PZT) was realized and studied in details. Both BiFe0.95Co0.05O3 and PbZr0.52Ti0.48O3 powders were fabricated using a conventional solid state method. Then composite-like systems of BFCO-PZTO (50-50) were synthesized through sintering in a wide range oftemperatures from 200° up to1000 °C. Magnetoelectric and magnetic measurements were performed and associated to structural characterizations using X-ray diffraction, Raman spectroscopy and scanning electron microscopy depending on the sintering temperature. We followed the evolution of the composite-like formation (BFCO-PZT) until the highest sintering temperature at which a full solid solution is obtained. A large improvement of the magnetoelectric coupling is observed in composite-like samples compared to that of BFCO alone, indicating that an interaction between the two compounds BFCO and PZT was established on a microscopic scale. The study of this magnetoelectric coupling shows that the coefficient decreases when the composite-like structure is changed towards solid solution. These results as well as the magnetic and dielectric measurements of this system will be presented. The approach we used reveal how one can improve ME response by constructing 3D-based composite using two different materials with the same perovskite structure by avoiding the detrimental solid solution form. Key words: Multiferroic, magnetism, magnetoelectric, ferroelectricity. References 1. Shimakawa, M. Azuma, and N. Ichikawa, Materials 4(1), 153 (2011). 2. Ramesh and N. A. Spaldin, Nature Mater. 6, 21 (2007). 3. P. Sazonov, I. O. Troyanchuk, M. Kopcewicz, V. V. Sikolenko, U. Zimmermann, and K. Barner, J. Phys. Condensed Matter 19, 046218 (2007). 4. P. Singh, K. D. Truong, P. Fournier, P. Rauwel, E. Rauwel, L. P. Carignan, and D. Menard, Appl. Phys. Lett. 92, 112505 (2008). 5. Fiebig, J. Phys. D: Appl. Phys. 38, R123 (2005). 6. W. Cheong and M. Mostovoy, Nature Mater. 6, 13 (2007). marzouki_arij@yahoo.fr

N.4.30
17:30
Authors : A.U. Abuova1, E.A. Kotomin 2,4, T.M. Inerbaev1, A.T. Akilbekov1,Yu. A. Mastrikov2,3
Affiliations : 1L.N. Gumilyov Eurasian National University,Mirzoyan str.2, Astana, Kazakhstan 2Institute of Solid State Physics, University of Latvia, Kengaraga str. 8, Riga, Latvia 3Materials Science and Engineering Dept., University of Maryland, College Park, USA 4Max Planck Institute for Solid State Research, Heisenbergstr.1, Stuttgart, Germany

Resume : Search of new efficient catalysts for solid oxide fuel cells (SOFC) remains a hot topic. The oxygen adsorption on Ag/LaMnO3 (001) catalyst surface was investigated using large scale first-principles density functional theory calculations. The energetically most favorable oxygen adsorption sites are found to be atop surface Mn atoms on the MnO2-terminated surface and on the hollow positions of the LaO-terminated LMO (001) surface. It is shown that pre-adsorbed Ag facilitates O2 adsorption on LaMnO3 (LMO) with a sharp increase in the adsorption energy on both MnO2 - terminated and LaO- terminated (001) LMO surfaces, which promotes O2 dissociation and further oxygen transport from cathode towards anode. The bond lengths, bond populations and charges are carefully analyzed. The adsorbed Ag on LMO strengthens its catalytic activity as SOFCs cathode by acting as an active center at the surface. The most favorable oxygen adsorption sites are found to be atop surface Mn atoms on the MnO2-terminated surface and on the hollow positions of the LaO-terminated LMO (001) surface. Presence of silver atom on both considered LMO (001) surfaces increases the adsorption energy of oxygen. This effect is more pronounced in the case of LaO-terminated surface in comparison with MnO2-terminated one.

N.4.31
17:30
Authors : Bum Ho Choi1, Jong Ho Lee1 and Jae Hyun Cho2
Affiliations : 1Center for Nano-Photonics Convergence Technology, Korea Institute of Industrial Technology 2Project Support Office, Jeonbuk Regional Division, Korea Institute of Industrial Technology

Resume : In this study, we have explored transparent metal and metal?oxide material for cathode application in transparent organic light-emitting diodes (OLEDs) to find out alternative to conventionally used Mg:Ag layer. Among candidate materials, we have explored Ca/Ag, Yb/Ag, Sr/V, Ba/Ag, WO3 and MoOx thin film by evaporation for cathode and analyzed their optical and electrical properties. In case of Ca/Ag combination for cathode application, 10nm thick Ca and 10nm thick Ag exhibited 75% of transparency in visible ray range and 11ohm/sq. of sheet resistance which is suitable for transparent OLEDs. 10nm thick WO3 showed 98.5% of transparency and 11.7ohm/sq. of sheet resistance. In addition, e-beam evaporated Sr (10nm)/V(7nm) combination followed by thermal treatment showed 92% of transparency with 8ohm/sq. of sheet resistance. White emission transparent OLEDs employing WO3 cathode material showed 63% of transparency and 94% of emission uniformity with 42lm/W of power efficiency. Furthermore, green emission transparent OLEDs showed 78lm/W of power efficiency without out-coupling film with 75% of transparency. Our study suggested that explored metal and metal-oxide materials are suitable for cathode material in transparent OLEDs.

N.4.32
17:30
Authors : Joon-Min Lee1,2, Chan-Hwa Hong2, Chang-Ho Lee2, Jeong-Jin Park2, Ho-Yeol Choi2, and Woo-Seok Cheong1,2*
Affiliations : 1. University of Science and Technology, Korea; 2. Electronics and Telecommunications Research Institute, Korea

Resume : In this study, high transmittance of window unified touch screen panels (TSPs) were fabricated by printing organic materials as an insulator between patterned electrodes, where window unified TSP had Tx and Rx electrodes on the single layer on the window. The intersection of the Tx and Rx electrodes needs to be separated by an insulator for touch-sensing. Conventionally, oxides (eg. SiO2) have been used as the insulators with lower transmittance. In order to replace them, we printed a highly transparent (> 99 %) organic insulator by silk-screen method and heat treatment. Then, Ag-paste was printed on the organic insulator layer as a narrow bridge to connect Rx electrodes. In results, 24? window unified TSPs were successfully fabricated, showing the high transmittance and good performance.

N.4.33
17:30
Authors : R. Desfeux,a* T. Carlier,a A. Ferri,a S. Saitzek,a M. Huvé,a A. Da Costa,a A. Bayart,a A. Tebano b
Affiliations : a Univ. Artois, CNRS, Centrale Lille, ENSCL, Univ. Lille, UMR 8181, Unité de Catalyse et Chimie du Solide (UCCS), F-62300 Lens, France. b CNR-SPIN and Department of Civil Engineering and Computer Science Engineering, University of Rome, Tor Vergata, Via del Politecnico, 00133, Rome, Italy

Resume : Due to their high Curie Temperatures (Tc ~ 1500°C), ferroelectric lanthanide titanium oxides with perovskite-layered structure offer very interesting perspectives for applications in severe environments [1]. Recently, we highlighted nanoscale ferroelectric/piezoelectric properties in (110)-epitaxial Nd2Ti2O7 thin films by Piezoresponse Force Microscopy [2]. Otherwise, introduction of insulating SrTiO3 layers within ferroelectric layers to form artificial superlattices has been shown promising to enhance physical properties of thin films [3]. In this study, we are interesting in the growth conditions and nanoscale electrical properties of Nd2Ti2O7/SrTiO3 superlattices deposited on (110)-oriented SrTiO3 substrates by pulsed laser deposition using the in-situ Reflection High Energy Electron Diffraction diagnostic. Structural and microstructural properties of the epitaxially grown samples are highlighted by X-Ray Diffraction and Transmission Electron Microscopy on cross-sections prepared by a Focused Ion Beam. Quality of the interfaces within the superlattices is investigated by High Angle Annular Dark-Field Scanning Transmission Electron Microscopy. Piezoresponse Force Microscopy and Conductive Atomic Force Microscopy for mapping the leakage current distribution are used to reveal the nanoscale electrical properties of these samples. [1] A. Sayir, S.C. Farmer, F. Dynys, Advances in Electronic and Electromechanical Ceramics, 2006, John Wiley & Sons, Inc. p. 57-68. [2] A. Bayart, S. Saitzek, M.H. Chambrier, Z. Shao, A. Ferri, M. Huvé, R. Pouhet, A. Tebano, P. Roussel, R. Desfeux, CrystEngComm 15 (21) (2013) 4341-4350. [3] L. Kim, J. Kim, D. Jung, J. Lee, U.V. Waghmare, Applied Physics Letters 87 (2005) 052903.

N.4.34
17:30
Authors : Urszula Klekotka, Dariusz Satula, Simo Spassov, Beata Kalska-Szostko
Affiliations : Institute of Chemistry, University of Bia?ystok, Cio?kowskiego 1K, 15-245 Bia?ystok, Poland; Faculty of Physics, University of Bia?ystok, Cio?kowskiego 1L, 15-245, Bia?ystok, Poland; Section du Magnétisme Environnemental, Centre de Physique du Globe de l?Institut Royal Météorologique de Belgique, 5670 Dourbes, Viroinval, Belgium; Institute of Chemistry, University of Bia?ystok, Cio?kowskiego 1K, 15-245 Bia?ystok, Poland

Resume : Magnetite nanoparticles (MNP), coated with various types of surface stabilizers have been studied in many research papers. Proper surface stabilization is of great importance since the blocking temperature of MNPs depends on size, morphology and kind of surfactant. In the study presented here, nanostructures were obtained by thermal decomposition of a Fe(acac)3 precursor in organic solvent. Five types of long-chain carboxylic acids (oleic, lauric, palmitic, stearic and caprylic acids) and four types of amines (oleylamine, hexylamine, dioctylamine, trioctylamine) have been tested for stabilization of nanoparticles. The obtained MNPs were examined by XRD, TEM and FTIR. Magnetic properties of the nanoparticles were tested by Mössbauer spectroscopy and Vibrating Sample Magnetometry. Magnetization and Mössbauer measurements showed how the stabilizing surface layer influences the magnetic state of the particles. From all tested agents hexylamine was found to be the best surface stabilizer because coating with this agent resulted in the most even MNP shapes and narrow size distributions compared to the other agents. The study shows also, how surfactant concentration influences the nanoparticles morphology and its properties. VSM measurements were performed under the Short Term Scientific Mission (COST Action RADIOMAG TD1402). The work was partially financed by EU founds (contract numbers POPW.01.03.00-20-034/09-00, POPW.01.03.00-20-004/11-00) and by NCN founds 2014/13/N/ST5/00568.

N.4.35
17:30
Authors : Pawel Peczkowski [1], Cezariusz Jastrzebski [2], Piotr Szterner [1], Marek Pawlowski [2],
Affiliations : [1] Institute of Ceramics and Building Materials, Department of Ceramic Technology, Postepu 9 Street, 02-676 Warsaw, Poland. [2] Warsaw University of Technology, Department of Physics, Koszykowa 75 Street, 00-662 Warsaw, Poland

Resume : The YBa2Cu3O7-y (where 0 < y < 1) superconductor (also called ?YBCO? or ?1:2:3?) is produced by calcination of a mixture of copper (II) oxide (CuO), barium carbonate (BaCO3) and yttrium (III) oxide (Y2O3) powders [1]. In order to obtain a new group of superconducting materials Re-BCO, the corresponding oxides of rare elements Re: Sc, La, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu were used [2]. In this study structural and studies of the materials were conducted by XRD and Raman Spectroscopy. Also, physical and electrical characteristics (e.g. electrical resistance and critical temperature) for the produced superconductors were investigated. The presentation shows experimental research and discussion of the results. [1] S. Alagöz, Production of YBCO superconductor sample by powder-in-tube method (PITM); and effect of Cd and Ga doping on the system, Turk. J. Phys., no. 33, p. 69-80, 2009. [2] H. C. Yang, M. H. Hsieh, H. H. Sung, C. H. Cen, H. E. Horng, Y. S. Kan, H. C. Cen, J. C. Jao, High-temperature resistivity of RBa2Cu3O7-y, where R = La, Pr, Nd, Sm, Eu, Dy, Ho, Er, and Tm, Phys. Rev. B, vol. 39, no. 13, p. 9203-9208, 1989.

N.4.36
17:30
Authors : M. Brychevskyi
Affiliations : Frantsevich Institute for Problems of Material Science of NASU 03680, Kyiv-142, 3, Krzhyzhanovsky St., Ukraine m.brychevskyi@gmail.com

Resume : It is known the strength of all materials including ceramics is structure depended property, for example, of averege grain size or total porosity. However, attempts that can compile these divergent and interinfluencing factors are usually empirical [1]. Strength of ceramics ? is dependent on the sintering temperature Ts and might be described as some complex function of structural components, primary porosity P, effective size of structural elements d and some effective surface energy ?, which describes quality of boundaries between all structural components and depends on amount and state of impurities along them [2]. The detailed study of structure and mechanical behavior of 1Ce10ScSZ (1-mol. % CeO2, 10-mol. % Sc2O3, 89-mol. % ZrO2) electrolyte ceramics shows that the fullest set of structural parameters which are suitable for a complex analysis might be obtained from ceramics made of three different types of zirconia powders, which differ by properties of initial particles and their agglomerates [3]. Finally, for interparticle and cleavage fracture micromechanisms, ceramic strength is described in above mentioned terms as where ? - the normalizing coefficient that determines the boundary quality. Reference 1. Knudsen F.P. J. Am. Ceram. Soc. ? 1959. ? 42(8). ? P. 376?388. 2. Rice R.W. Academic Press, New York, ? 1977. ? Vol. 11.? P. 199? 381. 3. Brychevskyi M., Vasylyev O. at al. Electron microscopy and strength of materials. Vol. 19, Kyiv, 2013.

N.4.37
17:30
Authors : O.V. Chukova, I.V. Moroz, S.G. Nedilko, A.A.Slepets, S.A. Nedilko, V.P. Scherbatskiy, T.A. Voitenko
Affiliations : Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska Str., UA-01601 Kyiv, Ukraine

Resume : Orthovanadates can exhibit unusual magnetic, optical, thermally-activated and X-ray luminescence properties those have very important applications in various fields. In particular, the RE-doped vanadates were considered recently as effective luminescent down-shifting materials for enhancement of solar energy harvesting by Si solar cells. This application requires vanadate materials with improved efficiency of luminescence excitation under light from near UV and violet spectral ranges. The most attention was paid to investigation of Eu-activated compositions. In this work we have synthesized and investigated three sets of Sm-activated samples as they could a better energy harvesting in the near violet spectral range. XRD study have shown that synthesized samples have monoclinic or tetragonal zircon structure as well as their mixture dependently on Sm and Ca concentrations. Luminescence properties also depend on concentrations and excitation wave length as well. At least two types of Sm3 centers were found by emission spectra. These centers have different excitation efficiency by light from the 350 ? 450 nm spectral range. Structures of the centers are discussed taking into account crystal structure, possible defects, morphology of the synthesized nanoparticles and surface effects. Influence of method of synthesis on formation of different centers is considered.

N.4.38
17:30
Authors : Simona Neagu1, Roxana Cojoc1, M?d?lin Enache1, Silviu Preda2, Crina Anastasescu2, J.M. Calderon-Moreno2, Adriana Rusu2, Mihai Anastasescu2, Mariuca Gartner2, Maria Zaharescu2
Affiliations : 1Institute of Biology Bucharest of the Roumanian Academy, 296 Splaiul Independen?ei, P.O. Box 56-53, Bucharest 060031, Roumania; 2?Ilie Murgulescu? Institute of Physical-Chemistry of the Roumanian Academy, 202 Splaiul Independen?ei, Bucharest 060021, Roumania

Resume : Nanomaterials become increasingly used over traditional bulk materials in many fields of applications, such as catalysis and photocatalysis, sensors, solar cells etc. One way to increase and even tailor their applicability can be reach by functionalization and immobilization of different bio-active species. The titanate nanotubes (TiNTs) were prepared by hydrothermal method using laboratory sol-gel powders in the presence of 10 M NaOH solution at 130-180 °C for various times, from 24 to 72 h. The SiO2 nanotubes (SiO2_NT) have been obtained by sol-gel method in a solution of tartaric acid, pure water and absolute ethanol, via the addition of ammonium hydroxide. TiTNs and SiO2_NT have been characterized by X-ray diffraction, scanning and transmission electron microscopy, thermogravimetric/differential thermal analysis, BET and porosity measurements, FT-IR and UV-VIS spectroscopy. Unlike the TiTNs, which underwent crystal structure transformation and a morphology modification, the SiO2_NT are very stable over a wide temperature range (up to 1200 C). The functionalization of the SiO2_NT and TiNT has been performed with halotolerant proteases and the influence of substrate concentration, pH values, ionic strength and temperature on the enzymatic activity was studied. It was found that the capacity of protease immobilization is higher on the TiNTs in comparison with SiO2_NT, although its catalytic activity is lower than for SiO2_NT.

N.4.39
17:30
Authors : #T.Goto, S.Suzuki*, K.Ishibashi*, Y.Yamamoto**
Affiliations : Faculty of Science and Engineering, Hosei University, 3-7-2 Kajino, Koganei, Tokyo, 184-8584, JAPAN * Comet Inc., 5-9-5 Toukoudai, Tsukuba, Ibaraki, 300-2635, JAPAN ** Graduate school of Sci. & Eng., Hosei University, 3-7-2 Kajino, Koganei, Tokyo, 184-8585, JAPAN # e-mail : tatsuya.goto.2i@stu.hosei.ac.jp

Resume : The CeO2 films incorporating Al2O3 were deposited on p-type Si substrats by RF magnetron sputtering using CeO2 and Al2O3 targets in the Ar ambient with 10% O2 introduction. The samples was annealed in either N2 or O2 at 500 °C for 30 minutes. The Al2O3 molar fraction ranged from 0.0 to 0.6 against CeO2 in the composition spread sample prepared by the combinatorial multi layered technique. With increasing Al2O3 molar fraction up to 0.1, the leakage current density of the sample annealed in N2 was once decreased to 1.6 × 10-8 A/cm^2 at the electric field of 1 MV/cm. This value was two orders of magnitude lower than that without Al2O3 incorporation. The dielectric constants of the samples annealed in O2 and N2 respectively decreased from 16 and 12 to 6 with the increase of Al2O3 to 0.15, and then remained almost unchanged regardless of the Al2O3 amount. In the range of the Al2O3 up to 0.15, it is considered that the films consisted individual phases of CeO2 and Al2O3 (Eg = 8.7 eV, k = 8 ~ 10) which increased the effective band-gap and decreased the dielectric constant. In the range of Al2O3 above 0.2, however, the leakage current density increased with the appearance of the bending points representing the additional conduction mechanisms on the I-V characteristics. It is considered that these behaviors resulted from the generated Ce-Al-O ternary compound having low band-gap and dielectric constant.

N.4.40
17:30
Authors : Noelia Benito, Marcos Flores
Affiliations : Laboratorio de Superficies y Nanoestructuras. Facultad de Ciencias Físicas y Matematicas, Universidad de Chile; Laboratorio de Superficies y Nanoestructuras. Facultad de Ciencias Físicas y Matematicas, Universidad de Chile

Resume : With the development of ultra-large scale integration (ULSI) devices, Cu has replaced Al as interconnection material due to its lower electrical resistivity (1.78 ·10-8 ? m at 293 K) and its higher melting point (1357.6 K) [1]. These properties make Cu a more resistant for corrosion and electromigration material. The Cu/SiO2 interface, which is the base of the Cu/SiO2/Si formation, has not been studied in depth. J. P. Espinós et al. studied the interfacial effects of Cu, CuO and Cu2O deposited on SiO2, observing changes in the modified Auger parameter ?`as the thickness of the Cu layer grows [2]. These changes could be connected with a modification in the coordination number of Cu, which provokes a change in the Madelung potential around the photoemitting element and a subsequent variation of the BE and ?`values. Other possibility is the formation of bonding interactions at the interface, due to the formation of M-O-M´ cross linking bonds at the interface, where the bridging oxide ions should have different electronic characteristics than in the bulk oxides [2]. Moreover, an important property of the Cu/SiO2 system is its catalytic activity [3-4].The surface and interface phenomena that occur are determined by the metal-support interactions [5], which are more intense in catalytic systems form by Cu nanoparticle on a flat SiO2 subtract [5-6]. This systems have been studied from morphological and compositional point of view, but there are no information about the interaction of the materials on the interface. Compared to the bulk properties, not only relatively little is known on the surface properties of Cu?silica mixed oxides but also on the first stages of oxidation of the Cu/SiO2 interface. In this work, we have deposited Cu onto SiO2 by e-beam evaporation. Once the Cu was evaporated, the samples were transferred to the analysis chamber, which in connected to the preparation chamber. The analysis chamber allows XPS measurements without exposing the sample to atmospheric conditions. This procedure allows us to study the growth kinetic of the Cu/SiO2 interface. During the growth kinetic, two different stages can be distinguish. During the first one, no metallic Cu is observed, but Cu+ and Cu2+ with tetrahedral and octahedral coordination are present. On the other hand, during the second stage of growth is when metallic Cu appears. Moreover, AFM measurements have been carried out during the Cu/SiO2 formation. It can be observed differences in grain the grain size and the roughness as a function of the Cu thickness. References 1. Matula, R. A. 1979, Journal of Physical and Chemical Reference Data, Vol. 8, p. 1147. 2. J. P. Espinós, J. Morales, A. Barranco, A. Caballero, J. P. Holgado, A. R. González-Elipe. 2002, Journal of Physical Chemistry B, Vol. 106, pp. 6921-6929. 3. Stéphanie Lambert, Caroline Cellier, Paul Grange, Jean-Paul Pirard, Benoit Heinrichs. 2004, Journal of Catalysis , Vol. 221, pp. 335-346. 4. Janusz Janas, Jacek Gurgul, Robert P. Socha, Stainslaw Dzwigaj. 2009, Applied Catalysis B: Environmental, Vol. 217, pp. 217-224. 5. L. C. A. van den Oetelaar, A. Partridge, S. L. G. Toussaint, C. F. J. Flipse, H. H. Brongersma. 1998, Journal of Physical Chemistry, Vol. 102, pp. 9541-9549. 6. L. C. A van den Oerelaar, A. Partridge, P. J. A. Stapel, C. F. J. Flipse, H. H. Brongersman. 1998, Journal of Physical Chemistry B, Vol. 102, pp. 9532-9540.

N.4.41
17:30
Authors : O. Chukova1, S.G. Nedilko1, V. Sheludko2, Yu. Titov1
Affiliations : 1 Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska Str.., 01033, Kyiv, Ukraine; 2 Oleksandr Dovzhenko National Glukhiv University, Sumy Region, 41400, Glukhiv, Ukraine

Resume : Perovskites are well known applied materials taking into account a wide range of their interesting properties. Some of their applications deal with photoluminescence properties, but emission intensity of such compounds usually is low comparably with some other oxide materials. Tantalates are also characterized by a high absorption cross-section. This feature makes them promising luminescence working media for various purposes and biomedical applications are among them, because such usage requires light transformer materials characterized by high efficiency of energy transformation in order to decrease irradiation of living tissues. The A3LaM3O12 (A = Sr, Ba; M = Nb, Ta) samples were synthesized by co-precipitation method. The phase composition and crystal lattice parameters were determined by XRD. Distortion rates and A/La cation distributions were calculated for inner-block and external-block polyhedrons of the perovskite layers. Luminescence emission spectra of all the investigated compounds are complex and contain two main bands with photon energies near 2.9 and 2.5 eV. These bands were assigned to electron transitions in the niobate and tantalate oxyanions. Relations of their distortions and cation distributions with changes in luminescence properties are discussed. Cations have been shown to play the main role in processes of luminescence excitation. Schemes of energy levels of the niobate and tantalate groups and corresponded emission and excitation transitions are considered.

N.4.42
17:30
Authors : N. K. Kumar, N. A. Singh, J. Das, R. Mitra
Affiliations : Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, West Bengal 721302, India

Resume : The investigation of 2 at.% Zr to Mo76Si14B10 (Si14Zr0) on the initial stage oxidation behavior has been observed lower mass loss during exposure at 1150 °C. The addition of Zr to Si14Zr0 has been refined the microstructure with ?-Mo, Mo3Si (A15) and Mo5SiB2 (T2) phases and improved the oxidation resistance. The oxidation response of Mo76Si14B10Zr2 (Si14Zr2) has been observed as transient stage at 1150 °C in dry air due to formation of B2O3-SiO2 glass oxide scale, therefore no mass change further oxidation. Thus, the top oxide scale has been observed negligible mass loss after 360 s and ZrO2 protects the further vaporization of MoO3 during oxidation due to evaporation temperature of ZrO2 is 2200 °C. Moreover, the oxide thickness and indentation fracture toughness (IFT) of substrate have been increased by followed the parabolic law as well as decreased the hardness of substrate upon exposure.

N.4.43
17:30
Authors : Saurav Prakash, Amit Verma, Ganesh Ji Omar, Soumya Sarkar, Siddhartha Ghosh, Thirumalai Venkatesan
Affiliations : NUS Graduate School for Integrative Sciences and Engineering; Indian Institute of Technology Kanpur; National University of Singapore Nanoscience and Nanotechnology Initiative; NUS Graduate School for Integrative Sciences and Engineering; National University of Singapore Nanoscience and Nanotechnology Initiative; National University of Singapore Nanoscience and Nanotechnology Initiative

Resume : Transparent electronic materials are increasingly in demand for a variety of optoelectronic applications. Tin doped Indium Oxide (ITO), Aluminum doped Zinc Oxide (AZO) are some of the commonly used transparent conducting oxides which have resistivity ~0.1 mohm-cm. Kim et al in a recent article showed La doped BaSnO3 single crystals have remarkably high mobility of 302 cm2/V.s at room temperature at a carrier concentration of 8 x1019/ cm2. It was also found to be stable at elevated temperatures. Barium Stannate (BaSnO3) is a wide band gap (3.1eV) semiconductor which has a perovskite structure (Lattice parameter = 4.11Å) which makes it a suited candidate to grow other functional oxides. In this study, we have prepared BaSnO3 perovskite thin films on STO (001) substrates with different La and O-vacancy doping levels using Pulsed Laser Deposition (PLD) technique. By lanthanum doping, we could achieve similar order of resistivity as ITO. We could also tune the electron concentration in the range ~1- 5.3 x 1020/ cm3 . For 1% La-doped sample, we found the highest carrier mobility of ~108 cm2/V.s at 300K which is the highest reported mobility in La-doped BaSnO3 films using PLD. Higher carrier concentrations could not be achieved due to solubility limit of La in BaSnO3. The vacancy doped samples were found to have lower mobility than the La doped films.

N.4.44
17:30
Authors : Fernando Ajejas1,2, Davide Maccariello1,2, Ruben Guerrero1, L. Méchin3, S. Flament3, J. Santamaria4, Julio Camarero1,2, Rodolfo Miranda1,2, and Paolo Perna1*
Affiliations : 1 IMDEA Nanoscience, c/ Faraday 9, Campus de Cantoblanco 28049 Madrid, Spain 2 DFMC, Universidad Autónoma de Madrid, 28049 Madrid, Spain & IFIMAC, Universidad Autónoma de Madrid, 28049 Madrid, Spain 3 GREYC (UMR6072) CNRS-ENSICAEN & Université de Caen Normandie, 6 Bd. de Maréchal Juin, 14050 Caen, France 4 GFMC, Departamento de Física de Materiales, Facultad de Física, Universidad Complutense de Madrid, Campus Moncloa, 28040 Madrid, Spain

Resume : Perovskite half-metallic manganites hold promise for spintronic applications, but are not yet available in today devices because of the lack of control of their magnetotransport properties. The reason for this relies on the complexity of the physical scenarios governing the interplay between a wide variety of coupled interactions. Different magnetoresistance (MR) contributions, such as colossal MR, Lorentz MR, spin-dependent scattering at grain-boundaries, domain-walls and other magnetic inhomogeneities, typically hide the switchable anisotropic magnetoresistance (AMR) that is more amenable for technological applications. In this work, we demonstrate the ability to engineer large anisotropic magnetoresistance in half-metallic La0.7Sr0.3MnO3 (LSMO) thin films by exploiting vicinal surfaces as substrate for the epitaxial PLD growth. These surfaces induce a surface symmetry-breaking, and hence specific magnetic anisotropy, which is responsible of the magnetization reversal pathways [1] and consequently of the magnetoresistance responses [2]. By combining simultaneous magnetization (vectorial Kerr) and transport measurements [3], we therefore disentangle the different contributions to the total MR response and demonstrate that AMR is in fact the dominant contribution [2]. In addition, we show that the artificially tailored film surfaces induce an extrinsic magnetic anisotropy that is responsible for the large AMR tunable, which can be tuned in sign and intensity by conveniently choosing the magnetization-current configuration [2]. These findings have a strong impact on the real applications of manganite-based devices for the high-resolution low field magnetic sensors or spintronics. REFERENCES [1] P. Perna, et al., J. Appl. Phys. 110, 13919 (2011); ibidem, J. Appl. Phys. 109, 07B107 (2011); P. Perna, et al., New J. Phys. 12, 103033 (2010). [2] P. Perna, et al., (2017) Adv. Funct. Mater. 2017, 1700664. [3] P. Perna, et al., Appl. Phys. Lett. 104, 202407 (2014) ; P. Perna, et al., Phys. Rev. B 92, 220422(R) (2015); P. Perna, et al., AIP Advances 6, 055819 (2016) ; P. Perna et al., Proc. of SPIE Vol. 9931, 99312I (2016) ; P. Perna, et al., Phys. Rev. B 86, 024421 (2012).

N.4.45
17:30
Authors : N. D. Scarisoreanu (1), V.Ion (1), R. Birjega (1), A. Andrei (1) ,M. Dinescu(1), V. Teodorescu (2), C. Ghica (2)
Affiliations : (1) NILPRP, P.O. Box MG-16, RO-77125, Bucharest, Romania. (2) NIMP-National Institute of Materials Physics, 077125 Bucharest-Magurele, Romania

Resume : The quest for revealing new or improved functionalities in the new lead-free piezoelectric and ferroelectric materials is at its peak nowadays. Family class materials such as BiFeO3 (BFO) or (Ba1?xCax)(ZryTi1?y)O3 (BCZT) are key materials in latest research due to their high dielectric constant and strong piezoelectric response or energy related properties. The new non-lead ceramic BCZT were intensified developed in last years. Varying the Ba/Ca and Zr/Ti ratios a huge dielectric constant and piezoelectric coefficient up to d33~650 pC/N were obtained. For BCTZ system the ferroelectric, dielectric and piezoelectric properties are maximized at MPB point. The major interest in BFO based materials are related with the efficient ferroelectric polarization-driven carrier separation in perovskitic BFO thin films, being studied for energy related applications. In this category, BFO, with excellent chemical stability and small band gap value, can have a huge impact. In this work we will show how the functional properties of such materials can be improved by tailoring the space of constraints (i.e epitaxial strain). We present the BFO and BCZT thin films with tailored properties for different functionalities needed in photonics, electronics and biotechnology. Using Pulsed Laser Deposition (PLD) technique, the role of epitaxial strain and fine stoichiometric changes induced into the BFO and BCZT nanostructured thin films during growth on the enhancement of electrical and piezoelectric properties is revealed. The thin films structural features and induced microstrain due to the lattice misfit between the lattice parameter of perovskite films and the used substrates were studied by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM).

N.4.47
17:30
Authors : A. Andrei (1), N. D. Scarisoreanu (1), V.Ion, R. Birjega (1), N.Dumitrescu (1, 2) ,M. Dinescu (1)
Affiliations : (1) NILPRP, P.O. Box MG-16, RO-77125, Bucharest, Romania (2) University of Craiova, Faculty of Sciences, Craiova, Romania

Resume : Among the different lead-free materials available for substitution of the PZT?s family, Na0.5Bi0.5TiO3 (NBT) appears as a promising candidate on account of its good ferroelectric and piezoelectric properties. The goal of this study was to investigate the optical, structural, dielectric and ferroelectric properties of NBT-BT thin films obtained by pulsed laser deposition as a function of composition, from pure NBT across and beyond morphotropic phase boundary (MPB) (x=0, 0.04, 0.06, 0.08). Dielectric and ferroelectric measurements were performed using an impedance analyzer HP 4294A and RT 66A Ferroelectric Test System. XRD, SEM, HR-TEM and AFM techniques have been used for morphologic and structural characterizations of NBT-BT films. Pyroelectric properties were investigated with a Woollam Variable Angle Spectroscopic Ellipsometer (VASE) system under different temperature conditions.

N.4.48
17:30
Authors : V. Ion1, N.D. Scarisoreanu1, A. Bonciu1, A. Moldovan1, V. Dinca1, M. Dinescu1, L.E. Sima3, M. Icriverzi3, A. Roseanu3
Affiliations : 1 National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele, Romania 2 CNR-ISC, Istituto de Sistemi Complessi, Area del Ricerca di Roma-Tor Vergata, Via del Fosso del Cavaliere 100, I-00133 Roma, Italy 3 Institute of Biochemistry of the Romanian Academy, 296 Splaiul Independentei, 060031, Bucharest, Romania

Resume : Doping the well-known BaTiO3 perovskite material with Ca and Zr allows obtaining a variety of solid solution compositions exhibiting different properties as compared with the host material. Employing laser based techniques to obtain non-toxic (Ba1?xCax)(ZryTi1?y)O3 - BCZT as biomaterial which supports cellular adhesion and proliferation of different kind of cells, can have an important impact on the integration of this material in different biomedical applications. Recent scientific reports demonstrated the applicability of BCZT in biomedical applications. Thin film of BCZT are currently studied due to high piezoelectric and dielectric properties, similar or even higher as compared with lead-based materials, for microelectronic devices. The BCTZ thin films have been obtained using Matrix Assisted Pulsed Laser Evaporation method. Starting from a frozen target of nanopowders of BCTZ and methanol, piezoelectric active thin films of BCTZ have been obtained on Pt-coated kapton substrates, the piezoelectric characterization of the films being made by Piezorespose Force Microscopy technique. The cell proliferation studies have been made using human bone marrow-derived mesenchymal stem cells (hBM-MSCs) which were seeded onto BCTZ biomaterial. The results suggest that BCTZ material led to an increased proliferation level and it has been proved that BCZT coatings on Kapton polymer substrates provide optimal support for osteogenic differentiation and viability of hBM-MSCs cells. Acknowledgements:This work has been financed by the National Authority for Research and Innovation in the frame of Nucleus programme - contract 4N/2016 and by project number PN-II-PT-PCCA 12/2013 (TUMORSENSE)

N.4.49
17:30
Authors : Ignasi Fina, Fanmao Liu, Florencio Sánchez, Josep Fontcuberta
Affiliations : Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Spain

Resume : Ferroelectric materials are receiving a renewed attention owing to their great application potential in non-volatile memories, optoelectronics, energy harvesting[1], photocatalysis[2], etc. For optoelectronic applications it is important to know how the ferroelectric properties are modified by the effect of light. In particular, it has been reported that the remnant polarization can be largely reduced by the application of light in the range of the UV, see f.i. ref. [3,4]. Ferroelectric materials are receiving a renewed attention owing to their great application potential in non-volatile memories, optoelectronics, energy harvesting[1], photocatalysis[2], etc. For optoelectronic applications it is important to know how the ferroelectric properties are modified by the effect of light. In particular, it has been reported that the remnant polarization can be largely reduced by the application of light in the range of the UV, see f.i. ref. [3,4]. To elucidate the key factor that dominates the light-induced screening in BaTiO3 thin films and to be able to modify it, a series of BaTiO3 thin films were grown using the same growth parameters but on different substrates imposing different epitaxial strain and with different thicknesses. Dramatic variation of the reduction of polarization by light (at 405 nm) has been observed among the studied films. X-ray photoelectron spectroscopy (XPS) shows a clear correlation between the content of OH- and H2O on the surface of the films and light-induced polarization reduction and both effects appear to be related to the strain state of the films. Trying to disclose the effect of H2O on the surface states different room-temperature treatments with continuous flux of water steam have been performed. The results show that chemically adsorbed OH- largely enhances the light-induced polarization reduction. These results illustrate a simple and convenient way of tuning surface states in ferroelectrics and this may be important for applications. Reference [1] K. T. Butler et al., Energ. Environ. Sci. 8, 838 (2015). [2] X. Bai et al., J. Phys. Chem. C 120, 3595 (2016). [3] D. Dimos et al., J. Appl. Phys. 76, 4305 (1994). [4] F. Liu et al., Adv. Electron. Mater. 1, 1500171 (2015).

N.4.50
17:30
Authors : I. Guler a* , N. Gasanly b
Affiliations : a Physics, Inter-Curricular Courses Department, Çankaya University, 06530 Ankara, Turkey b Department of Physics, Middle East Technical University, 06800 Ankara, Turkey

Resume : Thermoluminescence (TL) measurements were performed to evaluate the trap states in Tl2In2S3Se layered single crystals. TL experiments have been conducted with varying temperature from 10 to 300 K and warming rates from 0.2 to 1.0 K/s. From the analysis of both initial rise and curve fitting methods, the activation energy of the traps was obtained as 23 meV. The Chen?s method was also used to find activation energy. By means of this technique, the activation energy of the TL glow curve was calculated as 25 meV. From both Chen?s method and curve fitting method, the existence of mixed order of kinetics in Tl2In2S3Se crystal was found. The cross section to capture of the trap center was found out from the results of curve fitting method. The trap distribution of the crystals was investigated with different temperatures of illumination at a constant warming rate of 0.8 K/s. The temperatures of illumination changed from 10 K to 22 K. As a result of the increase in temperatures of illumination, the peak maximum values moved to higher temperatures and intensity of the TL curves decreased. This behavior shows us that quasicontinuous traps distribution is present in Tl2In2S3Se layered single crystals.

N.4.51
17:30
Authors : A. Sulich1, J. Z. Domagala1, J. Härtwig2, W. Paszkowicz1, A. Shekhovtsov3 and M. Kosmyna3
Affiliations : 1 Institute of Physics PAS, Al. Lotników 32/46, PL-02-668 Warsaw, Poland 2 European Synchrotron Radiation Facility, 6, rue Jules Horowitz, 38043, Grenoble, France 3 Institute for Single Crystals, NASU, Nauki Ave. 60, 61001 Kharkov, Ukraine

Resume : Previous studies on laser applications of borates have involved, in particular, materials based on various formulae such as R(BO2)3, AR2B10O19, A3R2(BO3)4, A3R(BO3)4, A4RO(BO3)3 and A3(BO3)2:R, as well as R doped borate glasses (A = divalent or trivalent cation, R = rare earth). Laser application for such hard, high melting materials with R = Y, La, Gd has been considered in refs. [1-5]. They have inhomogeneous broad spectral bands of the activator ions, efficient pumping in the wide range of LED temperatures and the laser emission wavelength tunable in a wide range. They are suitable, in particular, for mode-locked lasers. Understanding of the single-crystal defect structure is of importance for the material development; previous studies of such crystals [1] did not involve characterization of the defect structure. In the present study, the defect structure is characterized for Ca3Y2(BO3)4 and Ca3Gd2(BO3)4 crystals, undoped and doped with Nd or Ce, using the laboratory high-resolution X-ray diffraction and white-beam X-ray topography employing the synchrotron radiation. The crystals were grown using the Czochralski method. The combined data from reciprocal space mapping and X-ray topographs provided information on micromosaics and dislocations. Some crystals exhibit the block structure, with misorientation angles of the order of 0.2-0.4° (at most 1.5°). Generally, the obtained results suggest that the composition of investigated crystals is homogenous, as lattice parameters variations along the crystals are negligible (they do not exceed 0.01%). Acknowledgments: this work was partially financed from financial resources for science in the years 2013 - 2016 granted for the realization of the international project co-financed by Polish Ministry of Science and Higher Education, Grant Agreement 2819/7.PR/2013/2. [1] Y. Ji et al., J. Alloys Compds. 509, 9753-9757509, 9753 (2011). [2] Z.B. Pan et al., Appl. Phys. B 106, 197 (2012). [3] C. Tu et al., in Solid State Lasers, Ed.: A.H. Al-Khursan, (InTech, 2012), p. 63. [4] A. Brenier et al., J. Appl. Phys. 104, 013102 (2008). [5] B. Wei et al., J. Cryst. Growth 295, 241 (2006).

N.4.52
17:30
Authors : Wojciech Paszkowicz1, Damian Trzybiński2, Krzysztof Woźniak2, Tatiana Zajarniuk1, Andrzej Szewczyk1, Adrian Sulich1, Jaroslaw Z. Domagala1, Aleksey N. Shekhovtsov3, Miron B. Kosmyna3
Affiliations : 1 Institute of Physics, PAS, Aleja Lotników 32/46, PL-02-668 Warsaw, Poland 2 Department of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, PL-02-089 Warsaw, Poland 3 Institute for Single Crystals, NASU, Nauki Ave. 60, 61001 Kharkov, Ukraine

Resume : Various rare-earth containing borates have been considered as potential laser materials. One of advantages of borates is their stability at relatively high temperatures. Previous studies involve borates based on various compositions, one of them being A3R2(BO3)4 (A = divalent or trivalent cation, R = rare earth), as well as rare earth doped borate glasses. The Ca3R2(BO3)4 (CRB) borates have been reported in refs. [1,2]. For some of them, optical and thermal properties being important from the point of view of laser applications, have been determined: hardness and specific heat for Er3+/Yb3+ doped CRBs (R = La and Gd) [3], the optical properties for R = La [3], Gd [3-6] and Y [6,7] and thermal conductivity for R = Y, Gd and Nd [8]. Due to spatial separation of rare-earth cations in the crystal lattice of multicomponent R-containing oxides, the f-f luminescence of RE3+ ions is observed at room temperature. This effect can be applied e.g. in the design of microchip lasers. For the latter application, self-activated Nd-containing hosts are of great interest, because they are able to absorb up to 99% of pumping power for small thickness (few hundred um) and supply effective laser oscillations [9]. In this work, the structure, quality (mosaicity and blocks misorienation) and specific heat of binary borate Ca3Nd2(BO3)4 (CNB) crystal are studied. The crystal was grown using the Czochralski method from a charge prepared by solid state reaction. The growth process was carried out in argon from Ir crucible. The powder diffraction and single-crystal diffraction results show that CNB is isostructural with Ca3La2(BO3)4 [10]. The size of the orthorhombic (Pnma) unit cell is close to that determined in [2]. Specific heat of the CNB single crystal was measured over the temperature range from 2 to 300 K, in the magnetic field ranging from 0 to 7 T. The lattice contribution to the specific heat was separated. Below 15 K, a specific heat anomaly, interpreted as the Schottky anomaly related to excitations of Nd ions, and its evolution under magnetic field, was observed. [1] H. Bambauer H. et al., Z. Krist. 146, 53 (1977). [2] H.U. Bambauer, B. Kindermann, Z. Krist. 147, 63 (1978). [3] B. Wei et al., J. Cryst. Growth 295, 241 (2006). [4] Y. Ji, et al., J. Alloys Compds. 509, 9753-9757509, 9753 (2011). [5] Z.B. Pan et al., Appl. Phys. B 106, 197 (2012). [6] C. Tu et al., in Solid State Lasers, Ed.: A.H. Al-Khursan (InTech, 2012), p. 63. [7] A. Brenier et al., J. Appl. Phys. 104, 013102 (2008). [8] L.V. Gudzenko et al., Crystals 7, 88 (2017). [9] D. Jaque et al., J. Appl. Phys. 90, 561 (2001). [10] ICSD #261815.

N.4.53
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Session 5: Energy Storage : Sarbajit Banerjee (USA)
09:00
Authors : Patrik Schmuki
Affiliations : Department of Materials Science WW-4, LKO, University of Erlangen-Nuremberg, Martensstrasse 7, 91058 Erlangen, Germany

Resume : TiO2 nanomaterials have over the last 30 years attracted tremendous scientific and technological interest. Main research direction using TiO2 in functional applications are s the use in photocatalysis e.g. for the direct splitting of water into H2 and O2 to generate the potential fuel of the future, hydrogen; the use in Grätzel type solar cells and in biomedical applications. Over the past decades various 1D and highly defined TiO2 morphologies were explored for the replacement of nanoparticle networks and were found in many cases far superior to nanoparticles or their assemblies. Nanotubes or wires can be grown by hydrothermal or template methods, or even more elegantly, by self-organizing anodic oxidation. The latter is not limited to TiO2 but to a full range of other functional oxide structures on various metals and alloys can be formed. These advanced and doped morphologies can be grown on conductive substrates as ordered layers and therefore can be directly used as functional electrodes (e.g. photo-anodes). The presentation will focus on these highly ordered nanotube arrays of TiO2 and discuss most recent progress in synthesis, modification and applications towards energy conversion. Literature: (reviews): 1. P. Roy, S. Berger, P. Schmuki, Angew. Chem. Int. Ed. (2011), 2904 2. K. Lee, A. Mazare, P. Schmuki, CHEMICAL REVIEWS, 114 (2014) 9385

N.5.1
09:30
Authors : L. Iglesias, A. Sarantopoulos, F. Rivadulla
Affiliations : Centro de Investigación en Química Biológica y Materiales Moleculares (CIQUS); Centro de Investigación en Química Biológica y Materiales Moleculares (CIQUS); Centro de Investigación en Química Biológica y Materiales Moleculares (CIQUS), Spain

Resume : Achieving an accurate control over the formation and manipulation of cationic and anionic defects in transition-metal oxides is a novel route to discover new functional properties. In SrTiO3 (STO), the presence of oxygen vacancies, VO, plays a very important role in the transport properties of thin films and interfaces, such as the well-studied STO/LaAlO3 [1]. Due to the donor character of VO and the large electron mobilities, even the slightest concentration of VO produces a measurable electrical conductivity. On the other hand, strontium vacancies, VSr, also play a crucial role in the structural properties of the STO thin films, influencing in the rotation pattern of the TiO6 octahedra to accommodate the epitaxial strain. We present a thermodynamic study of VO formation in e-doped STO thin films grown by Pulsed Laser Deposition. Hall effect measurements confirmed that each VO is doubly ionized and donates two electrons to the conduction band of STO. Furthermore, our results demonstrate that both, compressive and tensile strain, leads to a decrease in the VO formation enthalpy. We also determined the existence of different rotation pattern of the TiO6 octahedra of the thin films under compressive or tensile strain, which is related with the unintentional presence of the VSr in the STO thin films [2]. Additionally, we show the possibility to manipulate the VO by applying an external electric field with an Atomic Force Microscopy tip. We demonstrate a reversible change in the local surface potential of the sample associated to the accumulation/depletion of VO, and determine the strain-dependence of the oxygen diffusion coefficient in STO. [1] A. F. Santander-Syro et Al, Nature, 469(2011) 189. [2] L. Iglesias et Al, Phys. Rev. B 95(2017) 165138.

N.5.2
09:45
Authors : Peter J. King, Mikko J. Heikkilä, Marko Vehkamäki, Kenichiro Mizohata*, Mikko Ritala, Markku Leskelä
Affiliations : Department of Chemistry, University of Helsinki *Department of Physics, University of Helsinki, Finland

Resume : LaNiO3 is a so-called "bad metal", a conductive perovskite metal-oxide. Such materials have resistivity higher than that of conventional metals, but low enough to be studied as electrode materials.1 The mechanism responsible for the conductive properties is not fully understood, but it is thought that maintaining 3+ Ni valence in the films is key in attaining metallic-like conductivity.2 For optimum results a stoichiometric, single-crystal film is desired. This talk will describe a method to grow epitaxial LaNiO3 by atomic layer deposition (ALD), with resistivity values comparable to those produced using other deposition techniques. LaNiO3 films were prepared on SrTiO3 substrates using La(thd)3, Ni(thd)2, and O3 as precursors. Epitaxial film formation was found to be strongly thickness dependent, necessitating a two-stage deposition process. First, a seed layer (~5 nm) was grown before a 750 °C air annealing step. Further deposition (up to ~30 nm in this study) could then be performed on top of the seed layer, with additional post-deposition annealing required to produce crystalline films. The films from the two-stage process were analyzed with TOF-ERDA, STEM and HRXRD and were found to be stoichiometric, epitaxial LaNiO3 in pseudocubic crystal structure as has been produced with techniques like MBE and PLD previously. The average resistivity was found to be uniform across the film and in the order of 300±50 micro-Ohm.cm, which compares well with literature values of films deposited with PLD,3 as well as being an order of magnitude improvement on polycrystalline LaNiO3 grown by ALD. 1 Jaramillo, R., et al. Nat. Phys. 10, 304 (2014). 2 Qiao, L. & Bi, X. EPL 93, 57002 (2011). 3 Tsubouchi, K. et al. Appl. Phys. Lett. 92, 262109 (2008).

N.5.3
10:00
Authors : Mohamed Bouras(1*), Mihai Apreutesei(1), Nicolas Baboux(2), Sébastien Cueff(1), Régis Debord(3), Nicolas Chauvin(2), Stéphane Pailhès(3), Romain Bachelet(1), Guillaume Saint-Girons(1)
Affiliations : (1) INL-CNRS/UMR 5270, ECL, 36 avenue Guy de Collongue 69134 Ecully cedex, France. (2) INL-CNRS/UMR 5270, INSA, 7 avenue Jean Capelle, 69621 Villeurbanne cedex, France (3) ILM-CNRS/UMR 5306, Univ. Lyon 1, 10 rue Ada Byron, 69622 Villeurbanne cedex, France

Resume : Perovskite oxides with general formula ABO3, thanks to the remarkable flexibility of their crystal structure that can host a variety of cations, present a wide range of remarkable physical properties (ferroelectricity, piezoelectricity, thermoelectricity?) that can be tailored by controlling the material structure and composition. In this context, molecular beam epitaxy appears as an unrivalled technic to design complex perovskite heterostructures and engineer their functionalities, since it provides many advantages: control of the growth down to the half-monolayer scale, flexibility for the control of the oxide composition, and control of heterogeneous interfaces that in particular allows for integrating oxide thin layers on silicon. In this communication, two recent results will be presented. We will first show that LaxSr1-xTiO3 (LSTO) epitaxial films with controlled electric/thermoelectric properties are very good candidates for on-chip thermal energy management. We have in particular explored the impact of La-doping effect on the thermoelectric and electric properties of high-quality LSTO films with low mosaicity (< 0.1°), and shown that electrical conductivity can exceed 104 S.cm-1 and thermoelectric figure of merit (ZT) can reach 0.1 at room temperature. We will then show how super-structuration of perovskite oxides in Ruddlesden Popper (RP) phases (An+1BnO3n+1) based on STO (Srn+1TinO3n+1) and BTO (Ban+1TinO3n+1) can be controlled to tune the oxide functional properties. We will also discuss the stability of the artificial phases regarding growth conditions and epitaxial strain.

N.5.4
10:15
Authors : J. Lyu, I. Fina, R. Solanas, J. Fontcuberta, F. Sánchez
Affiliations : Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra 08193, Barcelona, Spain

Resume : The properties of crystalline oxide thin films can depend largely on the lattice strain. Today, strain engineering by selecting a particular substrate is the main methodology to improve ferroelectric and other properties of epitaxial oxides. However the magnitude of the strain and the thickness of the film are limited due to plastic relaxation, and for most of the applications the oxides have to be integrated with silicon. We present here a different methodology. Instead of varying the epitaxial strain by changing the substrate, we control the residual strain present in epitaxial oxides on a given substrate. We show that the lattice strain of ferroelectric BaTiO3 thin films grown by pulsed laser deposition can be adjusted by a suitable balance of thermodynamics/kinetics in the growth simply by selecting properly the deposition parameters. For example, in the temperature window for epitaxial growth, the polar c-axis of BaTiO3 films thicker than 100 nm can be strained ad hoc up to more than 2%, being the ferroelectric polarization proportional to the strain. This is achieved in epitaxial BaTiO3 films integrated with Si(001), and high ferroelectric polarization and low leakage are obtained at deposition temperatures as low as around 450 °C. The new strategy has permitted an unprecedented level of control in the growth of ferroelectric BaTiO3 films on Si(001), and we also show that the strategy developed can be used with other substrates, like single-crystalline perovskites.

N.5.5
10:30 Coffee break    
 
Session 6: Logic Devices I : Albena Paskaleva (Bulgaria)
11:00
Authors : R. Keech,1 L. Ye,2 J.L. Bosse,2 G. Esteves,3 J, Guerrier,3 J. L. Jones,3 M. A. Kuroda,4 B.D. Huey,2 and S. Trolier-McKinstry1
Affiliations : 1Dept. Materials Sci. & Eng., and Materials Res. Inst., University Park, PA, USA 2 Dept. Materials Sci. & Eng., University of Connecticut, Storrs, CT, USA 3 Dept. Materials Sci. & Eng., North Carolina State University, Raleigh, NC, USA 3 Dept. Physics, Auburn University, Auburn, AL, USA

Resume : Piezoelectronic Transistors provide a potential CMOS replacement, but necessitate finely patterned, thin piezoelectric films with excellent piezoelectric response. This paper will discuss growth and characterization of both epitaxial and highly {001}-oriented lead magnesium niobate ? lead titanate (PMN-PT) thin films for this application. It was found that both film types exhibited similar, thickness-independent high-field ?r of ~300 with highly crystalline electrode/dielectric interfaces. Irreversible domain wall motion is the major contributor to the overall dielectric response and its thickness dependence. In clamped epitaxial films the irreversible Rayleigh coefficients reduced 85% upon decreasing thickness from 350 to 100 nm. The effective interfacial layers are found to contribute to the measured thickness dependence in d33,f measured by X-ray diffraction. High field piezoelectric characterization revealed a field-induced rhombohedral to tetragonal phase transition in epitaxial films. Using optical and electron beam lithography combined with reactive ion etching, the PMN-PT films were systematically patterned down to lateral feature sizes of 200 nm in spatial scale with nearly vertical sidewalls. Upon lateral scaling, there was an increase in both small and large signal dielectric properties, including a doubling of the relative permittivity in structures with width-to-thickness aspect ratios of 0.7. The longitudinal piezoelectric coefficient, d33,f, was interrogated as a function of position across the patterned structures by finite element modeling, piezoresponse force microscopy, and nanoprobe synchrotron X-ray diffraction. It was found that d33,f increased from the clamped value of 40-50 pm/V to ~160 pm/V at the free sidewall under 200 kV/cm excitation. The sidewalls partially declamped the piezoelectric response 500-600 nm into the patterned structure, raising the piezoelectric response at the center of features with lateral dimensions less than 1 ?m (3:1 width to thickness aspect ratio). The normalized data from all three characterization techniques are in excellent agreement.

N.6.1
11:30
Authors : Maciej Rogala, Pawel Dabrowski, Pawel Kowalczyk, Krzysztof Szot, Zbigniew Klusek
Affiliations : Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, 90-236 Lodz, Poland; Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, 90-236 Lodz, Poland; Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, 90-236 Lodz, Poland; Institute of Physics, University of Silesia, 40-007 Katowice, Poland; Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, 90-236 Lodz, Poland;

Resume : In 1971 Chua predicted existence of fourth passive electric element characterized by physical quantity called memrsitance. The memristance changes in function of a current flowing through memristor. If such the change does not exist the memristance is equal to the resistance. Strukov and colleagues were first who realized that the systems there have been investigating for years in fact were related to Chua?s idea of the memristor/memristance and show resistive switching behavior (RS). Particularly, TiO2 is considered as prototypical memristive material in which resistive switching phenomena allow for nonvolatile information storage [1,2]. In 2008 it was shown that the RS can be also observed in graphene a novel two dimensional carbon material with extraordinary electrical mobility combined with high optical transparency in visible light spectrum. Soon afterwards the RS was discovered in the graphene oxide (GO) films. Unfortunately, RS mechanism in GO is still under debate. In the presentation we will focus on models describing RS phenomena observed in TiO2 [3,4] and propose possible mechanism for RS in GO [5,6]. The experimental data obtained in nanometer scale by STM/STS and AFM/LC-AFM together with XPS/UPS results will be outlined and discussed. Finally we show possible application of GO in transparent and flexible electronics. This work is supported by the National Centre for Research and Development Poland under the project POIR.04.01.02-00-0046/16 and by the National Science Centre Poland under the project 2016/21/D/ST3/00955. [1] K. Szot, et al. Nanotechnology, 22, 254001 (2011) [2] M. Rogala, et al. Adv. Funct. Mater. 25, 6382 (2015) [3] M. Rogala, et al. Appl. Phys. Lett. 106 263104 (2015) [4] M. Rogala et al. Carbon 103, 235 (2016)

N.6.2
12:00
Authors : Alexander Hardtdegen, Hehe Zhang, Susanne Hoffmann-Eifert
Affiliations : Peter Grünberg Institut (PGI-7), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany

Resume : Atomic layer deposition (ALD) is a common growth method for ultrathin and dense metal oxide layers which are integrated into resistive random access memory (ReRAM) cells, as it unifies several benefits such as perfect thickness control, conformal 3D-growth and a high reproducibility of the grown layers. A major challenge remains the adjustment and control of the proper defect density of the metal oxide layers that are involved in the switching process. Especially for the realization of a moderate electroforming voltage at acceptable ON-state leakage currents of the switching devices, bilayer structures are advantageous. In this study, plasma-ALD grown HfO2 is combined with different ?qualities? of TiOx. The later ones are achieved by variation of the oxygen source, either oxygen plasma or water vapor, which were shown to affect the phase formation of the TiOx layer. The impurity contents of the films are in the 1 at% regime and thus the phase formation is addressed to growth kinetics rather than to significant differences in the impurity contents of the films. Integrated into ReRAM cells, differences of plasma-HfO2/plasma-TiO2 and plasma-HfO2/thermal-TiOx based devices with respect to electroforming voltage and resistive switching behavior will be discussed in comparison to the films? structure and chemistry.

N.6.3
12:15
Authors : Jaroslaw Domaradzki, Tomasz Kotwica
Affiliations : Wroclaw University of Science and Technology, Poland

Resume : Attention of research community in the recent years focuses more and more on oxide thin film structures with new functionalities. One of the emerging direction of research is looking for the advanced materials that could be used for manufacturing of transparent electronics devices equivalent to conventional ones, such as: transparent resistors, diodes, transistors, capacitors, and so forth. One of interesting feature that is observed in some selected oxide-based layered structures is occurrence of memory and resistive switching effects. That would open new possibilities for manufacturing of transparent memory devices. Present work consists of discussion on structure and electrical properties of multicomponent transparent oxide semiconducting thin films based on mixture of titanium-copper or titanium-cobalt oxides. The thin film structures were prepared using multitarget magnetron sputtering setup that was created by the Authors according to their own concept and allows on deposition of thin films with gradient element distribution. In the work, the results obtained for the structures with different shape of Cu or Co gradient distribution has been presented and a possible mechanism for resistive switching has been discussed.

N.6.4
12:30 Lunch break    
 
Session 7: Logic Devices II : Susan Trolier-McKinstry (USA)
13:45
Authors : Sarbajit Banerjee
Affiliations : Department of Chemistry and Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77845 (USA)

Resume : The focus of this talk will be electron correlated mixed valence ternary vanadium oxides where closely linked lattice, orbital, and spin degrees of freedom give rise to pronounced structural and electronic instabilities. The binary vanadium oxides VO2 and V2O3 have long been canonical examples of compounds showing pronounced electronic instabilities underpinned by the interplay of electron?phonon coupling and strong electron correlation. In recent work, we have explored the intriguing electronic phase diagrams of low-dimensional ternary vanadium oxides with the formula MxV2O5 where M is an intercalating cation and x is its stoichiometry. Several of these compounds show colossal metal?insulator transitions and charge ordering phenomena. The talk will focus on mechanistic understanding of these transitions based on DFT+U calculations of electronic structure and synchrotron X-ray absorption/emission spectroscopy and imaging studies. The insulating phases of these compounds are characterized by the stabilization of small polarons, which give rise to ?mid-gap? states that reside intermediate in energy between the valence and conduction bands. The stabilization of polarons and their eventual melting to form a delocalized metallic phase has interesting implications for the design of cathode materials for intercalation batteries as well as for realizing Mott field-effect transistors. The discovery of a novel topochemical intercalation route has provided access to a wide variety of MxV2O5 phases, thereby enabling tuning of correlation strengths and allowing for the partial decoupling of the lattice and electronic facets of the transitions. Finally, dimensional reduction of layered MxV2O5 phases via ion exchange and exfoliation to few-layered nanosheets further allows for modulation of the correlation strengths and the bandgaps of these compounds as a result of the loss of 3D structural coherence. References 1) Justin L Andrews, Luis R De Jesus, Thomas M Tolhurst, Peter M Marley, Alexander Moewes, Sarbajit Banerjee, Intercalation-induced Exfoliation and Thickness-modulated Electronic Structure of a Layered Ternary Vanadium Oxide. Chemistry of Materials 2017, DOI: 10.1021/acs.chemmater.7b00597. 2) Luis R De Jesus, Gregory A Horrocks, Yufeng Liang, Abhishek Parija, Cherno Jaye, Linda Wangoh, Jian Wang, Daniel A Fischer, Louis FJ Piper, David Prendergast, Sarbajit Banerjee, Mapping Polaronic States and Lithiation Gradients in Individual V2O5 Nanowires Nature Communications 2016, 7, 12022. 3) Peter M. Marley, Gregory A. Horrocks, Kate E. Pelcher, and Sarbajit Banerjee, Transformers: The Changing Phases of Low-Dimensional Vanadium Oxide Bronzes, Chemical Communications 2015, 51, 5181-5198. 4) Peter M. Marley, Tesfaye A. Abtew, Katie E. Farley, Gregory A. Horrocks, Robert V. Dennis, Peihong Zhang, and Sarbajit Banerjee, Emptying and Filling a Tunnel Bronze, Chemical Science 2015, 6, 1712-1718. 5) Peter Marley, Adam A. Stabile, Chun Pui Kwan, Sujay Singh, G. Sambandamurthy, and Sarbajit Banerjee,* Charge Disproportionation, Charge Ordering, and Voltage-Induced Metal-Insulator Transitions Evidenced in ?-PbxV2O5 Nanowires, Advanced Functional Materials 2013, 23, 153-160.

N.7.1
14:15
Authors : Alexander Shluger, David Gao, Moloud Kaviani, Jack Strand, Oliver Dicks, Adnan Mehonic, Anthony Kenyon
Affiliations : Department of Physics and Astronomy, University College London, UK; WPI-AIMR, Tohoku University, Japan; Department of Electronic and Electrical Engineering, University College London, UK

Resume : Most current electronic and electrochemical devices are stacks of thin films and interfaces operating under electrical stress. Nanometre-thick oxide films play crucial role in performance of these devices. Injection of excess electrons and holes into oxide films and the nature of electron trapping sites are important for our understanding of the mechanisms that govern the formation of conductive filaments in resistance switching memory devices, the dielectric breakdown in microelectronic devices, and the performance of photo-electrochemical and oxide fuel cells. Our theoretical modelling combined with experimental observations demonstrates that structural disorder in amorphous SiO2, Al2O3 and HfO2 films creates precursor sites which can spontaneously trap up to two electrons or holes in deep states in the band gap. This results in weakening of Me?O bonds, which can be broken upon thermal activation, creating an O2- interstitial ion and a neutral O vacancy. O2- interstitial ions can easily diffuse through the oxide and in devices are guided to the positive electrode by the electric field. Thus electron injection can lead to the formation of new defects and significantly alter the structure of oxide films at large injection densities. The creation and field-driven movement of oxygen ions causes changes in oxide structure on a much larger scale than previously thought.I will discuss the implications of this effect for the mechanisms of electrical breakdown and resistance switching in electronic and memory devices.

N.7.2
14:45
Authors : Maciej Rogala 1, Gustav Bihlmayer 2,3,4, Wolfgang Speier 4, Christian Rodenbücher 2,4, Pawel Dabrowski 1, Zbigniew Klusek 1, Krzysztof Szot 2,4,5
Affiliations : 1 Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, 90-236 Lodz, Poland; 2 Peter Grünberg Institut, Forschungszentrum Jülich, 52425 Jülich , Germany; 3 Institute for Advanced Simulations, Forschungszentrum Jülich, 52425 Jülich , Germany; 4 JARA ? Fundamentals of Future Information Technology, Forschungszentrum Jülich, 52425 Jülich , Germany; 5 Institute of Physics, University of Silesia, 40-007 Katowice, Poland

Resume : TiO2 is considered as prototypical memristive material in which resistive switching phenomena allow for nonvolatile information storage [1]. Among the transition metal oxides crystalline rutile has been identified as one of the most suitable for device development and also for describing the nanoscale mechanism behind memristive switching. It is now well established that resistive switching in TiO2 crystals is not a material property by itself but is a highly localized phenomenon in the bulk material related to reduction processes and nanofilamentary structures. We describe an approach which allows for the generation of quasi-homogenous switchable regions near the surface which can be used for high density data storage by resistive switching processes. The thermal preparation method that we propose leads to the modification of extended defects in the crystal and creation of ?new? nanofilamentary structures of high density near the surface allowing for preferential and fully controllable bipolar switching. Based on experimental investigations and simulations we deeply analyze the nature of such crystal structure transformation and the mechanism responsible for the observed resistive switching processes [2]. This work is supported by the National Science Centre, Poland (project 2016/21/D/ST3/00955) and by the German Science Foundation DFG (SFB 917 ?Nanoswitches?). [1] K. Szot, et al. Nanotechnology, 22, 254001 (2011) [2] M. Rogala, et al. Adv. Funct. Mater., 25, 6382 (2015)

N.7.3
15:00
Authors : Lide Yao, Sampo Inkinen, Sebastiaan van Dijken
Affiliations : NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, Espoo, FI-00076 Aalto, Finland

Resume : Oxygen defects can have a profound effect on the physical properties of transition metal oxides. Electric-?eld driven migration of oxygen vacancies provides a viable mechanism for the formation, rupture and reconstruction of conducting ?laments in insulating oxides, an effect that is used in nanoscale resistive switching devices [1,2]. In complex oxides, oxygen vacancies can radically alter a plurality of intrinsic properties via valance changes and structural phase transitions [3]. The ability to reversibly control the concentration and pro?le of oxygen vacancies in oxide nanostructures would thus open up comprehensive prospects for new functional ionic devices. Advancements in this direction require experimental techniques that allow for simultaneous measurements of oxygen vacancy dynamics, atomic-scale structural effects and macroscopic physical properties. Here, we use in situ transmission electron microscopy (TEM) to demonstrate reversible switching between three resistance states in epitaxial La2/3Sr1/3MnO3 ?lms [4]. Simultaneous high-resolution imaging and resistance probing indicate that the switching events are caused by the formation of uniform structural phases. Reversible horizontal migration of oxygen vacancies within the manganite ?lm, driven by combined effects of Joule heating and bias voltage, predominantly triggers the structural and resistive transitions. Our ?ndings open prospects based on dynamic control of physical properties in complex oxide nanostructures. [1] R. Waser and M. Aono, Nat. Mater. 6, 833 (2007). [2] J.J. Yang et al., Nat. Nanotech. 8, 13 (2013). [3] S. Kalinin and N.A. Spaldin, Science 341, 858 (2013). [4] L. Yao, S. Inkinen, and S. van Dijken, Nat. Commun. 8, 14544 (2017).

N.7.4
15:15
Authors : B. Negulescu, C. Daumont, C. Autret, J. Wolfman
Affiliations : GREMAN, Univ. F. Rabelais, Tours, France

Resume : Magnetoelectric coupling in oxide based heterostructures gives the possibility to electrically control the magnetization, with promising applications in the field of spintronics [1], [2]. Strong magnetoelectric coupling was demonstrated in magnetic thin film structures deposited on ferroelectric substrates and allowed to identify several coupling mechanisms, namely the strain transfer via converse piezoelectric and magnetostriction effects or the ferromagnetic electronic structure modification by the ferroelectric polarization. In thin film multilayer structures the piezoelectric effect is reduced by the low dimensionality, thus the interfacial charge-mediated coupling effect can predominate. We report here on the magnetoelectric properties of BiFe0.95Mn0.05O3 (BFMO) / Ni multilayer structure. BFMO displays ferroelectricity at room temperature as well as canted G-type antiferromagnetism. Therefore, a third type of coupling mechanism should be considered in such structure, due to exchange interactions between the antiferromagnetic structure of BFMO and the ferromagnetic Ni structure. The magnetoelectric coupling in the studied system manifests through the ferromagnetic coercive field modulation with the electric field. The effect is non-volatile, reversible and cyclable at room temperature. In light of our results, charge-mediated coupling mechanism seems to be the origin of the studied effect. [1] V. Garcia, M. Bibes, A. Barthélémy, C. R. Physique 16 (2015) 168?181 [2] J.-M. Hu, L.-Q. Chen, C.-W. Nan, Adv. Mater. 2016, 28, 15?39

N.7.5
15:30 Coffee break    
 
Session 8: Magnetic and Ferroelectric Properties : Markku Leskela (Finland)
16:00
Authors : Radoslaw Przenioslo
Affiliations : Faculty of Physics, University of Warsaw, ul. Pasteura 5, PL 02-093 Warsaw, Poland

Resume : The Neumann?s principle states that "If a system has a certain group of symmetry then any physical observable of that system must also possess the same symmetry?[1]. The application of this statement leads to new conclusions concerning alpha-Fe2O3 and Cr2O3. Both these oxides are believed to have corundum-type crystal structures described with the trigonal space group R-3c (this group posess a 3-fold rotation axis). Literature data clearly indicates that the canted magnetic orderings of both alpha-Fe2O3 [2] and Cr2O3 [3] are described with a symmetry group without 3-fold rotation axis. According to the Neumann?s principle one can expect that the symmetry of the crystal structure of alpha-Fe2O3 and Cr2O3 is not trigonal (without 3-fold rotations). Synchrotron radiation diffraction studies of alpha-Fe2O3 [4] and Cr2O3 [5] shows that their crystal structures are described by the monoclinic space group C2/c instead of R-3c. The unexpected result is that the monoclinic symmetry is observed not only below the Néel temperature, T_N=950K of alpha-Fe2O3 but also above T_N. [1] A.P. Cracknell Applied Group Theory, Pergamon Press, Oxford, 1968. [2] C.G. Shull, W.A. Strauser & E. Wollan, Phys. Rev. 83, 333 (1951). [3] P.J. Brown, J.B. Forsyth, E. Lelievre-Berna & F. Tasset, J. Phys. Condens. Matter, 14, 1957 (2002). [4] R. Przenios?o, I. Sosnowska, M. Stekiel, D. Wardecki, A. Fitch, & J.B. Jasi?ski, Physica B, 449, 72 (2014). [5] M. Stekiel, R. Przenios?o, I. Sosnowska, A. Fitch, J.B. Jasi?ski, J. A. Lussier, & M. Bieringer Acta Cryst. B71, 203 (2015). [6] P. Fabrykiewicz, M. Stekiel, I. Sosnowska & R. Przenios?o, Acta Cryst B73, 27 (2017).

N.8.1
16:30
Authors : W. Prellier,1 O. Copie,1,2 J. Varignon,3,4 H. Rotella,1 G. Steciuk,1 Ph. Boullay,1 A. Pautrat,1 A. David,1 B. Mercey,1 Ph. Ghosez,3
Affiliations : 1. Laboratoire CRISMAT, CNRS UMR 6508, 6 BD Mal Juin, F-14040 Caen Cedex, France 2. Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine, F-54506 Vand?uvre-lès-Nancy, France 3. Theoretical Materials Physics, Q-MAT, CESAM, Université de Liège, Allée du 6 aout, 20, 4000 Sart Tilman, Belgium. 4, Unité Mixte de Physique UMR 137 CNRS/Thales, 1 avenue A. Fresnel, F-91767 Palaiseau, France

Resume : Transition metal oxides having a per- ovskite structure present a wide range of functional properties ranging from insulator-to-metal, ferroelectricity, colossal magnetoresistance, high-temperature superconductivity and multiferroicity. Such systems are generally characterized by strong electronic correlations, complex phase diagrams and competing ground states. In addition, small perturbation induced by external stimuli (electric or mag- netic field, temperature, strain, pressure..) may change structure, and ultimately modify the physical properties. Here, we synthetize an orthorhombic perovskite praseodymium vanadate (PrVO3), which is grown on strontium titanate substrate. We show that the control of the content of oxygen vacancies, the so-called chem- ical strain, can indeed result in unexpected properties. We further demonstrate that the Nel temperature can be tuned using the same substrate in agreement with first-principles calculations, and demonstrate that monitoring the concentration of oxygen vacancies through the oxygen partial pressure or the growth temperature can produce a substantial macroscopic tensile strain of a few percents. Funding from ANR-LABEX is acknowledged

N.8.2
17:00
Authors : J. Kaczkowski
Affiliations : Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznan, Poland

Resume : We report the effect of doping with Y and La and hydrostatic pressure on structural, electronic, and ferroelectric properties of BiFeO3. We found that BiFeO3 undergoes a phase transition from rhombohedral (space group R3c) to orthorhombic (polar Pn21a and non-polar Pnma) structure. The phase transition caused by hydrostatic pressure appears at 5 GPa. In case of Bi1-xRExFeO3 the structural phase appears for x=0.125. The total energy difference between polar (Pn21a) and non-polar (Pnma) orthorhombic phases is less than 1 meV/f.u. This close a coexistence of these phases beyond T=0 K or under other conditions. The similarities between hydrostatic pressure and doping suggest that the latter can be regarded as a proxy for hydrostatic pressure, with an equivalence of 1% Y = 0.09 GPa and 1% La = 0.04 GPa. The experimentally obtained value was 1% La = 0.05 GPa [1]. The calculated spontaneous polarization for BiFeO3, Bi0.875La0.125FeO3, Bi0.875Y0.125FeO3 is 90 ?C/cm2, 83 ?C/cm2, 85 ?C/cm2, respectively [2, 3]. For undoped case our result is in good agreement with previous experimental and theoretical works [4]. References: [1] Ch.S. Knee, M.G. Tucker, P. Manuel, S. Cai, J. Bielecki, L. Börjesson, S.G. Eriksson, Chem. Mater. 26 (2014) 1180 [2] M. Pugaczowa-Michalska, J. Kaczkowski, J. Mater. Sci. 50 (2015) 6227 [3] J. Kaczkowski, in preparation [4] G. Catalan, J.F. Scott, Adv. Mater. 21 (2009) 2463 This work was supported by the National Science Centre, Poland through Grant No. DEC-2016/21/D/ST3/03444

N.8.3
17:15
Authors : D. Braun, M. Schmidbauer, M. Hanke, A. Kwasniewski and J. Schwarzkopf
Affiliations : Leibniz Institute for Crystal Growth, D-12489 Berlin, Germany; Leibniz Institute for Crystal Growth, D-12489 Berlin, Germany; Paul-Drude Institute for Solid State Electronics, D-10117 Berlin, Germany; Leibniz Institute for Crystal Growth, D-12489 Berlin, Germany; Leibniz Institute for Crystal Growth, D-12489 Berlin, Germany

Resume : Ferroelectric materials with a high piezoelectric response and flexible domain wall arrangement are essential for novel technologies as e.g. energy harvester. A possible pathway to enhance the electromechanic response is given in monoclinic phases where the electrical polarization vector is able to rotate within the mirror plane of the monoclinic unit cell. In materials with tetragonal or orthorhombic symmetry, the alignment of the domain walls is restricted to symmetry elements of the crystal yielding exclusively 45° or 90° domain wall angles. However, this restriction is released in monoclinic phases providing a new degree of freedom for domain engineering. In combination with a high piezoelectric response, such a system would be of high technological relevance. As a proof of concept, strained ferroelectric KxNa1-xNbO3 thin films were grown epitaxially on (110) NdScO3 substrates with metal-organic chemical vapor deposition. According to linear elasticity theory, the (100)pc and (001)pc crystallographic orientations concurrently occur in the films leading to the formation of a a1a2/MC multi-domain state showing up as a herringbone pattern. The domain wall angles within the herringbone can be systematically varied by changing the potassium content x, which is correlated to the monoclinic distortion angle. These results represent a first experimental verification of a flexible domain wall arrangement in monoclinic phases and agree well with values based on a domain model.

N.8.4
 
Poster Session II : ---
17:30
Authors : A. B Makama (1), Salmiaton A. (2), Elias B. Saion (3), Thomas S.Y. Choong (2), N. Abdullah (2)
Affiliations : (1) Department of Chemical Engineering Technology, The Federal Polytechnic, Nasarawa; (2) Department of Chemical and Environment Engineering, University Putra, Malaysia; (3) Department of Physics, University Putra, Malaysia

Resume : Vestigial quantities of antibiotics in wastewater are linked to the evolution of antibiotic resistant bacteria that exposes human and animal health to grave danger. Ciprofloxacin is a widely used antibiotic against gram-negative and gram-positive bacterial pathogens. This work investigated the influence of operating conditions in the removal of ciprofloxacin in suspended solution of porous ZnO/SnS2 photocatalyst under visible light irradiation. The effects of initial antibiotic concentration, catalyst dosage, and initial pH of solution were investigated. The process efficiency was evaluated in terms of antibiotic degradation. Experimental results evidenced that the highest degradation of the antibiotic occurred in the zwitterionic state at natural pH of 6.1. The ZnO/SnS2 photocatalyst exhibited stability at pH of 6.1.

N.8.5
17:30
Authors : F. Bouhjar , B. Marí and B. Bessaïs
Affiliations : a. Institut de Disseny i Fabricació, Universitat Politècnica de València. Camí de Vera s/n 46022 València (Spain) b. Laboratoire Photovoltaïques, Centre de Recherches et des Technologies de l?Energie Technopole H.lif 2050 (Tunisia) c. University of Tunis

Resume : Abstract Polycrystalline Hematite thin films doped by Cr were successfully deposit on glass substrate coated with fluorine-doped tin oxide (FTO) by a facile hydrothermal method. The hydrothermal bath consisted of an aqueous solution containing 25 mL capacity was filled with 20 mL aqueous solution containing 0.15 M of FeCl3.6H2O and 1 M NaNO3 at pH 1.5 (adjusted by HCl) . A piece of FTO glass slide heated at 100°C for 6 h in an oven and naturally cooled down to ambient temperature and subsequently the as-deposited samples were annealed in air at 550 °C for 4 hours. The structure and morphology of the as-synthesized products were characterized by X-ray diffraction (XRD), field-emission electron microscopy (FESEM), and High-resolution transmission electron microscopy (HRTEM). The effect of doped Cr were proven by defraction peaks (012) and (104) shifs to the lower angls. the photoelectrochemical performance of the thin films was eximined by chronoamperometry tecnique. Results of these studies showed that Cr doped films exibited higher photoelectrochemical activity over un-doped ?-Fe2O3 thin films. The highst photocurrent density of 0.015 mA cm-2 was obtaind for 16% Cr doped films in 1 M NaOH electrolyte under standerd illumination conditions ( AM 1.5 G, 100 mW cm-2). This high photoactivity can be attributed to the high active surface area and increasd doner density caused by Cr doping in the ?-Fe2O3 films. The best performing samples were 16% Cr doped which had Incident Photon Conversion Efficiencies (IPCE?s) at 400 nm, with an applied potential of 0.4V vs Ag/AgCl. These IPCE values were 22 times higher than the undoped sample for the 16% Cr sample. The increase in performance is attributed to an improvement in the charge transport properties within the films and not due to significant changes in the electrocatalytic rates due to dopants residing at the surface.

N.8.6
17:30
Authors : Hee-Joong Kim, Sae-Young Hong, Dae-Hwan Kim, Hwan-Seok Jeong, Chan-Yong Jeong, and Hyuck-In Kwon*
Affiliations : School of Electrical and Electronics Engineering, Chung-Ang University

Resume : Recently, zinc oxynitride (ZnON) is attracting a significant attention as an active material of the high-mobility thin-film transistor (TFT) for next-generation high-resolution, high-frame rate, and large-size displays. In this paper, we investigate the carrier transport mechanism in a high-mobility ZnON TFT by analyzing the gate bias and temperature dependence of conductance and field-effect mobility (?FE) in the subthreshold and above-threshold regions, respectively. In the subthreshold region, the variable range hopping and trap-limited band transport are considered as dominant carrier transport mechanisms in the ZnON TFT at temperatures below ~ 207 K and above ~ 243 K, respectively. In the above-threshold region, the ?FE almost linearly depends on 1/T (T: absolute temperature) at low temperatures, however, ?FE decreases with an increase in the gate overdrive voltage and temperature at high temperatures above room temperature. It represents that the trap-limited band transport is the dominant carrier transport mechanism at low temperatures, but the phonon scattering is the dominant mechanism limiting ?FE at high temperatures in the ZnON TFT in the above-threshold region.

N.8.7
17:30
Authors : G. Vertsioti, D. Stamopoulos
Affiliations : (1) Institute of Nanoscience and Nanotechnology, National Center for Scientific Research ?Demokritos?, 153 10, Aghia Paraskevi, Greece (2) Department of Solid State Physics, National and Kapodistrian University of Athens, Zografou Panepistimioupolis, 157 84, Zografou, Greece; (1) Institute of Nanoscience and Nanotechnology, National Center for Scientific Research ?Demokritos?, 153 10, Aghia Paraskevi, Greece (2) Department of Solid State Physics, National and Kapodistrian University of Athens, Zografou Panepistimioupolis, 157 84, Zografou, Greece

Resume : Composite compounds that exhibit strong magnetoelectric coupling have attracted much interest thanks to their potential room-temperature applications, e.g. low-energy-consumption storage devices. In composites with ferromagnetic and ferroelectric constituents the electric control of magnetism is, most commonly, strain-mediated by the inverse piezoelectric effect. Here we study composite samples of Fe3O4 micro/nano-particles embedded in a PZT matrix. Specifically, starting from the complete series of PZT-x%Fe3O4 with 0%?x?50% per weight prepared at T=1000 0C for 2 h in air, we focused on x=5%, e.g. PZT-5%Fe3O4, and studied the piezoelectric and magnetic properties at room temperature, in great detail. Experimentally, the strain-electric field curve, S(Eex), was recorded with a local method based on optical microscopy (OM) that enables us to monitor the dimensional changes of the sample under the variation of an external electric field, Eex. Relaxation data of the remanent magnetization were recorded with a SQUID magnetometer as host cryostat for the application of an external magnetic field, Hex, while we used a modified sample rod to apply the Eex. The combined OM and SQUID data prove that the relaxation rate (RR) of remanent magnetization presents a butterfly-like dependence on Eex, exhibiting maximum RR values at the extrema points of S(Eex). Accordingly, S(Eex) can be used as an effective variable to control the remanent magnetization (a candidate parameter for information storage in relevant devices) in the PZT-5%Fe3O4 composite compounds studied here.

N.8.8
17:30
Authors : Tomasz Kotwica, Jaroslaw Domaradzki, Danuta Kaczmarek, Michal Mazur, Damian Wojcieszak
Affiliations : Wroclaw University of Science and Technology

Resume : In recent years, fabrication and examination of the memristor structures have become more and more popular thanks to intensive development in micro- and nanotechnology, especially semiconducting nanomaterials and nanostructures. Among various types of the RAM memories, resistive RAM memory (ReRAM) is gaining more and more interest due to high density of packaging and high speed of operation. Thanks to that, the search for the materials based on oxides, which exhibit resistive switching, including such transition metal oxides (TMO) as ZnO or TiO2 has started. Characteristic behavior of this type of memristor structures is that they exhibit change of resistance by applying electric impulses, which results in appearance of pinched hysteresis loop in the current-to-voltage plane. As a result a memristor structure has ability to remember its resistance state. This work contains a short review on the subject of thin film structures with memory effect and own original results acquired during electrical investigations of thin film of oxide compounds based on titanium and copper. The results showed dependence of observed characteristics on the construction of prepared thin films (composition, shape of element-gradient distribution) and measurement conditions (e.g. frequency, sweeping time).

N.8.9
17:30
Authors : Paramita Maiti (a,b), Puspendu Guha (a,b), Jatis Kumar Dash (c), Parlapalli Venkata Satyam (a,b)
Affiliations : (a) Institute of Physics, Sachivalaya Marg, Bhubaneswar-751005, Odisha, India (b) HomiBhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400085, India. (c) School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar, India

Resume : In this work, we report on the growth of monoclinic ?-MoO3 nano-ribbons on varied substrates like Si (100), FTO, HOPG having almost similar morphologies keeping the substrate temperature at 350 °C by molecular beam epitaxy (MBE) technique. Scanning electron microscopy (SEM) images depict randomly oriented,out of plane nano ribbons of MoO3. For 10 nm MoO3 deposition the typical length, width, and aspect ratio (as defind by the ratio of length over width) of the nano-ribbons are 74 ± 6 nm, 12.0 ± 0.4, 6.1 ± 0.3 nm, respectively.With the increase in thickness of MoO3 at substrate temperature of 350 °C the length of the nano ribbons also increases (from 58 to 195 nm), but there is no significant change in width of the as-grown structures; hence the aspect ratio increases with increase in thickness (from 3.9 to 14). We have experimentally established the possible growth direction in [011] by thickness dependent study.Morphology of MoO3 structures found to depend on the growth temperature.

N.8.10
17:30
Authors : S. Vangelista1; R. Piagge2; S. Ek3;T. Sarnet3; G. Ghidini2; A. Lamperti1;
Affiliations : 1CNR-IMM - MDM Laboratory, Via C. Olivetti 2, Agrate Brianza (MB) I-20864 Italy; 2STMicroelectronics, Via C. Olivetti 2, Agrate Brianza (MB) I-20864 Italy; 3Picosun Oy, Tietotie 3, Espoo FI-02150 Finland;

Resume : In the last years, CeO2 based materials attracted much attention for their use in many technological areas. For some devices CeO2 needs to be grown on metallic substrates, but few reports exist on CeO2 deposited on metals. Here, we studied the structural properties of ALD grown CeO2 films deposited on Si or TiN. In particular, we unveiled the differences in the film properties depending on the substrate [1]. Moreover, we studied the effects of temperature and atmosphere in post-deposition annealing on the CeO2 films, including crystalline structure, grain size and shape, and Ce chemical state. CeO2 films deposited at 250°C by ALD are polycrystalline cubic phase on both substrates, but their crystallographic preferential orientation is along < 200> direction for CeO2/Si and < 111> direction for CeO2/TiN. Further CeO2 films interface roughness and concentration of Ce3+ species depend on the substrate. We also found that 900 °C annealing enhances the diffraction signal of the < 200> crystalline orientated grains in CeO2/Si, which is explained into the frame of the Mochvan?Demchishin model. Our results help the comprehension of ceria ALD growth and add relevant findings for material design and integration. This work was partially supported by ECSEL-JU R2POWER300 project under grant agreement n.653933. [1] S. Vangelista et al., Structural, Chemical and Optical Properties of Cerium Dioxide Film Prepared by Atomic Layer Deposition on TiN and Si Substrates, Thin Solid Films (2017) accepted

N.8.11
17:30
Authors : Davide Barreca,1 Giorgio Carraro,2 Chiara Maccato,2 Alberto Gasparotto,2 Cinzia Sada,3 Teresa Andreu,4 Olena Pliekhova,5 Dorota Korte,5 Ur?ka Lavren?i? ?tangar,5 Juan Ramón Morante,4 Gustaaf Van Tendeloo6
Affiliations : 1 CNR-ICMATE and INSTM, Department of Chemistry, Padova University, 35131 Padova, Italy; 2 Department of Chemistry, Padova University and INSTM, 35131 Padova, Italy; 3 Department of Physics and Astronomy, Padova University and INSTM, 35131 Padova, Italy; 4 Catalonia Institute for Energy Research (IREC), Barcelona, Spain; 5 Laboratory for Environmental and Life Sciences, University of Nova Gorica, 5001 Nova Gorica, Slovenia; 6 EMAT, University of Antwerp, 2020 Antwerpen, Belgium

Resume : The present work is focused on a plasma-assisted approach for the fabrication of Fe2O3-TiO2-Au nanosystems with tailored features. Specifically, the adopted strategy involved the initial growth of Fe2O3 nanostructures by plasma enhanced-chemical vapor deposition (PE-CVD) on fluorine-doped tin oxide (FTO) substrates, followed by the sequential functionalization with TiO2 and Au via radio frequency (RF)-sputtering, and final thermal treatment in air. The target nanosystems were characterized by a multi-technique approach, in order to investigate the interrelations between their chemico-physical properties and the processing conditions. The proposed route enabled the fabrication of pure nanocomposites, characterized by the presence of ?-Fe2O3 (hematite), an amorphous thin TiO2 overlayer, and Au nanoparticles with a controlled spatial distribution. The intimate contact between the various constituents was of considerable importance to exploit their mutual interplay in photo-activated processes. In this regard, preliminary functional tests for photoelectrochemical water splitting and self-cleaning end-uses evidenced that the control of Fe2O3-TiO2-Au interfacial interactions is a key tool to address the nanosystem potential in both renewable energy generation and pollutant decomposition. D. Barreca et al., Solar Energy Materials and Solar Cells, 2017, 159, 456.

N.8.12
17:30
Authors : K. Kavi Rasu, S. Moorthy Babu
Affiliations : Crystal Growth Centre, Anna University, Chennai- 600 025, India.

Resume : A series of Dy3+ doped RbGd(WO4)2 (RGW) phosphors were synthesized by sol gel method using citric acid as a chelator and ethylene glycol as a binder. Powder XRD, SEM, FT-IR, Raman, photoluminescence and decay analysis were used to characterize the synthesized phosphors. Powder XRD pattern of the samples match well with the standard JCPDS card no- 45-0472, which confirms the formation of scheelite type monoclinic structure RGW compound and the particles with plate like morphology were observed from SEM image. Liberation of organic species and the tungstate ribbon formation of the sample during calcination process were analysized by FT-IR and Raman spectra. Excitation spectrum of the Dy3+:RGW phosphor shows a broader band at the lower wavelength region due to the charge transfer band of O2- ?Dy3+ and O2- ?W6+ transition and sharp excitation peaks at the higher wavelength region due to the f-f transition bands of the Dy3+ ions. In emission spectrum, strong peak at 574 nm for electric dipole 4F9/2 ? 6H15/2 transition and relatively weak peak at 487 nm for magnetic dipole 4F9/2 ? 6H13/2 transition was observed. Also, the effects of Dy3+ doping concentration on the crystal structure, luminescence properties and lifetime of the Dy3+:RGW phosphor were investigated in detail. The CIE color coordinates of the phosphor was evaluated (x=0.347, y=0.387) and the values are closer to the standard values designated for white phosphor (x=0.333, y=0.333).

N.8.13
17:30
Authors : Tomasz A. Krajewski (1) , Penka Terziyska (2), Grzegorz Luka (1), Elzbieta Lusakowska (1), Rafal Jakiela (1), Emil S. Vlakhov (2), Elzbieta Guziewicz (1)
Affiliations : (1) Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, PL?02668 Warsaw, Poland; (2) Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd, 1784 Sofia, Bulgaria;

Resume : Zinc oxide is very attractive material for optoelectronics. As for many of its applications control of electrical properties is crucial, a lot of reports deal with the possible reasons of high n-type conductivity of this material. Noteworthy, the electron density reported for ZnO grown by different methods is 10?15 orders of magnitude higher than its intrinsic value, derived from the energy gap. The current work presents possible contributions to the n?type behavior of ZnO films grown by Atomic Layer Deposition. The room?temperature photoluminescence (RTPL) and Secondary Ion Mass Spectroscopy (SIMS) investigations suggest important role played by the zinc?related defects in their electrical response. This is supported by increasing n value (from 1.7×10^(17) cm^(-3) to 8.6×10^(19) cm^(-3)) with increasing ZnO growth temperature. We show that the RTP process results in changes in the defect?related RTPL, suggesting the contributions of defects of miscellaneous origin in different spectral range, i.e., RTP in N_(2) enhances the emission at 2.23?2.38 eV (ascribed to the oxygen vacancies), whereas RTP in O_(2) activates the PL nearby 1.70 ? 1.90 eV (where V_(Zn) defects are dominating). The work was supported by the Polish National Centre for Research and Development (NCBiR) through the project PBS2/A5/34/2013 and by the EU 7th FP REGPOT project INERA (GA 316309) of ISSP-BAS.

N.8.14
17:30
Authors : Anna Ka?mierczak-Ba?ata1), Jerzy Bodzenta1), Piotr Firek2) *Contact author: akazmierczak@polsl.pl, phone: +48 32 237 10 06
Affiliations : 1) Institute of Physics CSE, Silesian University of Technology, Konarskiego 22B, 44-100 Gliwice, Poland 2) Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, Warszawa 00-662, Poland

Resume : The aluminum oxides thin films are electrical insulators with high temperature resistance and high hardness. Thanks to physical properties, the Al2O3 thin films are applied as mechanically and chemically protective layers, heat resistance components and electric insulators in optoelectronic and electronic devices. The aluminum oxide is a high band gap material (?9 eV), with a high breakdown electric field (5?10M Vcm-1), a high permittivity (8.6?10), high thermal stability up to at least 1000 °C and remains amorphous under typical processing conditions [1]. Amorphous Al2O3 layers are found to significantly improve physical and electrical characteristics in GaAs MOS capacitors. They enhance thermal stability by blocking the diffusion process of oxidizing species upon annealing [2]. The Al2O3 thin films are applied as a high-k dielectrics in MOSFETs and DRAMs to replace silicon dioxide as the gate dielectric [3-7]. A dual-gated graphene FETs are produced with 2 nm Al2O3 top layer deposited on graphene [8]. Thermal properties of thin films are very important due to their applications. Nowadays, the progressive miniaturization and increasing integration of electronic devices causes problems with efficient heat dissipation from devices. Heat management is the key factor to improve functionality and reliability of the structure. The aim of this work was characterization of thermal properties of thin oxides films deposited on various substrates and correlation with morphology to study the influence of technological parameters on heat transport properties. Samples were produced using the magnetron sputtering method, well known technique used for deposition of thin metallic films as well as their oxides and nitrides. In this process atoms were released from a target in a strong magnetic field and condensed on a substrate in a high vacuum environment. In case of compound deposition the atoms react with ionized gases before condensation, e.g. oxygen, nitrogen. Determination of the thermal conductivity of Al2O3 samples was realized by the use of scanning thermal microscopy (SThM). This nondestructive method allowed for quantitative measurements of thermal properties with high spatial resolution. Determination of thermal conductivity was based on calibration curve build on SThM signal measured for reference samples of known thermal conductivity. The calibration procedure enabled the objective characterization of thermal properties of thin films and allowed to study the influence of substrate on thermal properties of the layer. References [1] H. C. Lin, P. D. Ye, G. D. Wilk, Appl. Phys. Lett. 87 (2005) 182904. [2] D. C. Suh, Y. D. Cho, S. W. Kim, D.-H. Ko, Y. Lee, M.-H. Cho, J. Oh, Appl. Phys. Lett. 96 (2010) 142112. [3] Frank M. M. et al, Appl. Phys. Lett. 83 (2003) 740. [4] Kim S. K. and Hwang C. S., J. Appl. Phys. 96 (2004) 2323. [5] Huang M. L. et al, Appl. Phys. Lett. 87 (2005) 252104. [6] Duenas S. et al, J. Appl. Phys. 99 (2006) 054902. [8] Xu M. et al, J. Appl. Phys. 99 (2006) 074109 [9] B. Fallahazad, K. Lee, G. Lian, S. Kim, C. M. Corbet, D. A. Ferrer, L. Colombo and E. Tutuc, Applied Physics Letters 100 (2012) 093112.

N.8.15
17:30
Authors : M.A. Pietrzyk, M. Stachowicz, P. Dluzewski, A. Wierzbicka, A. Kozanecki
Affiliations : Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46 PL-02668, Warsaw, Poland

Resume : We present the synthesis of ZnO/ZnMgO heterostructures on r- and c- plane Al2O3 by MBE and investigation of their structural and optical properties. The structures were grown at oxygen-rich conditions at temperature of 550°C. We demonstrate that it is possible to grow a good quality nanocolumns on c- plane Al2O3 substrate without employing a catalyst such as Au or Ag. We have studied also shift between polar- and nonpolar- ZnO/ZnMgO quantum wells. The non-polar (a-plane) ZnO/ZnMgO nanocolumns were achieved on semi-polar (r-plane) sapphire substrate while on polar c-plane substrate was used to obtain a polar c-orientation of the nanostructures. We present the research of ZnMgO nanocolumns with ZnO QWs located in single nanocolumns. The studied samples consist of two ZnO/ZnMgO quantum wells with the wells widths of 1.5 and 4 nm. The quantum wells were separated with 15 nm ZnMgO barrier. All samples were characterized with XRD, PL at different temperatures, TEM and SEM. We measured also the effects of a piezoelectric field on the spectroscopic properties ZnO/ZnMgO QWs in the strained ZnMgO self-assembled nanocolumns. We compared the luminescence spectra of ZnO/ZnMgO structures grown on the semi-polar substrate with r orientation and on polar c-oriented substrate. It is probably the first experiment comparing the quantum confined Stark effect for structures of different polarities, grown on Al2O3 substrates of different crystallographic orientations.

N.8.16
17:30
Authors : C. Mieszczynski 1, R. Ratajczak 1, E. Guziewicz 2, A. Turos 1,3
Affiliations : 1 National Centre for Nuclear Research, Soltana 7, 04-500 Otwock, Poland; 2 Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland; 3 Institute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw, Poland;

Resume : Ion implantation effects in semiconductor compounds have been widely studied in the last decade by many groups. However, a lack of complete understanding remains on the mechanism of damage buildup of compound crystal. The RBS/c technique is typically used for the analysis of structural properties of ion implanted single crystals by many authors. Unfortunately, oversimplified methods of spectral analysis have been typically applied, which may produce misleading results. ZnO is a very promising material for semiconductor device applications. In order to tune the optical emission from ZnO into the visible spectral range the optically active centers have to be formed. Recently, the studies on REs (rare earth) doped materials have received considerable interest for their possible applications in the light emitters. ZnO commercial single crystals (MaTecK) and epitaxial ZnO thin films, grown by atomic layer deposition (ALD) were implanted with 300 keV Er ions to fluencies ranging from 1e14 to 5e16 at/cm2. Quantitative analysis of the damage has been carried out using Monte Carlo simulation code McChasy, which allows to differentiate between type of defects. Model of structural transformation has been conceived based on their evolution as a function of ion fluence. Obtained differences between two investigated materials are presented and discussed in details.

N.8.17
17:30
Authors : E. Guziewicz, E. Przezdziecka, D. Snigurenko, D. Jarosz, B.S. Witkowski and W. Paszkowicz
Affiliations : Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, PL- 02668 Warsaw, Poland

Resume : In the paper we address the problem of a stable p-type conductivity of zinc oxide, which is the main obstacle in a wide application of this material in optoelectronics. Polycrystalline ZnO and ZnO:N films were grown at low temperature (100oC) by thermal Atomic Layer Deposition (ALD) under oxygen rich conditions. Low temperature photoluminescence (PL) spectra reveal emission at 3.36 eV as well as acceptor-related emissions at 3.302 and 3.318 eV. Annealing at 800oC leads to a considerable enhancement of PL at 3.302 eV in the ZnO:N. Based on temperature dependent photoluminescence spectra we calculated activation energies of acceptors related to the 3.302 eV and 3.315 eV PL peaks. The calculated activation energies suggest that low temperature deposition and oxygen-rich conditions provide a ZnO material with relatively shallow acceptor levels. We tentatively ascribe this levels to the nitrogen-hydrogen complexes. Acknowledgements. The work was supported by the Polish National Centre for Research and Development (NCBiR) through the project PBS2/A5/34/2013. + Author for correspondence: guzel@ifpan.edu.pl

N.8.18
17:30
Authors : E. Prze?dziecka1*, A. Wierzbicka1, K. Paradowska2, W. Lisowski3, R. Jakie?a1, M. Stachowicz1, E. P?aczek-Popko2, A. Kozanecki1
Affiliations : 1Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46 PL-02-668 Warsaw, Poland 2 Department of Quantum Technologies, Faculty of Fundamental Problems of Technology, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland 3 Institute of Physical Chemistry, Polish Academy of Sciences, M. Kasprzaka 44/52, 01-224 Warsaw, Poland

Resume : Zinc oxide (ZnO) is a promising candidate for many opto-electronic applications as UV LEDs and photodetectors. ZnO has recently received a lot of attention due to its high radiation hardness and thus possible application in space. The ZnO:Sb layers with different Sb concentration (from 0.77% to 1.73%) were grown by MBE on a- and r- plane Al2O3 substrates in polar and no polar directions. Raman spectroscopy, photoluminescence, X-ray, SIMS and XPS measurements provided information about composition and strain in the material. The binding energy shift of the Sb3d peak observed in the XPS data has been correlated with XRD results. Additionally, the Raman spectra, besides typical sapphire and zinc oxide modes, include also additional modes at 511 and 531 cm-1 associated with the presence of Sb dopant. The differences between layer growth on polar and nonpolar direction was observed both in optical and structural characterizations. The research was supported by the NCN project DEC-2013/09/D/ST3/03750 and partially by the statutory grant Wroclaw University of Technology S50013.

N.8.19
17:30
Authors : Takashi Ehara, Marina Abe, Ryo Iizaka
Affiliations : Faculty of Human Studies, Ishinomaki Senshu Univeristy; Faculty of Science and Engineering, Ishinomaki Senshu Univeristy

Resume : The influence of substrate temperature and postdeposition annealing condition on structural, optical, and electrical properties of p-type semiconductor CuAlO2 thin films prepared by rf-magnetron sputtering has been investigated. The CuAlO2 thin films were deposited using oxygen gas as the sputtering gas and employing synthesized CuAlO2 target. The depositions were carried out at 2.66 Pa of sputtering pressure with rf-power of 100W. The substrate temperatures were 20°C (RT) - 600°C, and the postdeposition annealing temperatures were 700°C - 1000°C in nitrogen, respectively. The as?grown films deposited on quartz substrates were amorphous and brown colored. These films show X-ray diffractions of CuAlO2 after a postdeposition annealing at higher temperature than 700°C. Colours of the films become thin brown at annealing temperature at 700°C, and opaque white or transparent at higher temperature than 800°C. Transparency of the films showed dependency not only on the annealing temperature but also on substrate temperature in film depositions. At substrate temperature of 200 or 300°C, and annealing temperature of 800°C transparency of the films become most preferable. Resistivity of the films also becomes the lowest, less than 100 ohm-cm, at substrate temperature of 200 or 300°C, and annealing temperature of 800°C.

N.8.20
17:30
Authors : Dinidu Perera (1), Avishi Abeywickrama (1), Federico Zen (2), Khairul Hoque (2), Paula E. Colavita (2), Dilushan R. Jayasundara (1,2)
Affiliations : 1. Department of Physics, University of Colombo, Colombo 3, Sri Lanka; 2. School of Chemistry, University of Dublin Trinity College, College Green, Dublin 2.

Resume : Chemical processing of graphene via reduction of graphene oxide has been regarded as a scalable and an economical method for most graphene-based applications. Recently graphene oxide itself has attracted significant attention due to its solution dispersibility and for its oxygen functionalities. As a result graphene oxide has become the primary raw material in developing new technologically advanced materials specifically in the areas of nanocomposites, functional coatings, paints and electrode material for chemical and biological sensing. However, one of the biggest challenges in the use of chemically processed graphene oxide or graphene in the above applications is the randomness of its oxygen functionalities and their inhomogeneous spatial distribution. Therefore, as part of controlling the process, one needs to understand the mechanism and the kinetics of the process that forms graphene oxide, and its subsequent reduction to graphene. In this study we look at graphene oxide and reduced graphene oxide synthesized from high purity vein type crystalline graphite under varying oxidation and reduction conditions. These samples were then characterized by a combination of spectroscopic and microscopic techniques that include infrared reflection absorbance spectroscopy, x-ray diffraction, x-ray photoemission spectroscopy, thermo gravimetric analysis, Raman spectroscopy, ultraviolet?visible spectroscopy, scanning electron microscopy and atomic force microscopy. The results were analyzed to identify the structural variations that occur during the oxidation and reduction processes respectively. The results obtained during oxidation indicate a rapid incorporation of oxygen functionalities and a complete interlayer expansion from that of graphite. Continued oxidation resulted in an increase in interlayer spacing and a complex interlayer strain relationship. These observations can be related to the attachment and subsequent prorogation of oxygen functionalities within the graphitic layers. It was also observed that exfoliation ability of expanded graphite oxide into single layer grapehen oxide in aqueous solutions is preceded by an abrupt change in the material structure and oxygen functionalities. Further the observed exfoliation of graphene oxide in aqueous solutions occurred at a much lower reaction time period than reported in literature for similar chemical treatment processes to obtain graphene oxide from graphite. The resulting graphene oxide obtained show large lateral dimensions in the range 5 to 10 micron with minimal morphological defects to the basal plane structure. The thermal reduction of synthesized graphene oxide was carried out under varying temperatures and the data indicate a significant level of reduction at temperatures as low as 200 degree Celsius. The reduction data also indicate a modulation in the optical band gap corresponding to the reduction temperature. Keywords: Graphene Oxide, Vein Graphite, Oxidation, Reduction Acknowledgment: This publication has emanated from research conducted with the financial support of University of Colombo under the grant AP/3/2/2016/CG/29 and of the National Science Foundation Sri Lanka under the OSTP grant OSTP/2016/46.

N.8.21
17:30
Authors : Michelle Marie S. Villamayor (1,2,3), Laetitia Laversenne (1,2)
Affiliations : 1 CNRS, Inst NEEL, F-38000 Grenoble, France 2 Univ. Grenoble Alpes, F-38000 Grenoble, France 3 LPSC, Université Grenoble-Alpes, CNRS/IN2P3, 53 rue des Martyrs, 38026 Grenoble, France

Resume : VO2 was synthesized on Si, SiO2, MgO and Al2O3 substrates by microwave-assisted physical vapor deposition. The morphology of the surface were observed via SEM and AFM. On Si and SiO2 random smooth-edged and bacilli-shaped structures were the dominant feature. On MgO, the film had sharp and smooth-edged irregular grains. Patterned triangular parallelepipeds and ball-like structures grew on the Al2O3. The presence of VO2 was confirmed by XRD. At room temperature, Raman spectroscopy showed that Si, SiO2 and MgO-grown vanadium dioxide exhibited a shift signature similar to the M1 phase while the Al2O3-deposited VO2 had the signature shift of the M2 phase. The difference in the growth formation will be discussed in regards to the substrate surface energy and thermal conductivity.

N.8.22
17:30
Authors : Koji Abe, Hiroki Hata
Affiliations : Department of Electrical and Mechanical Engineering, Nagoya Instituite of Technology

Resume : Electrochemical treatment was used to modify properties of ZnO films deposited by RF magnetron sputtering. Constant current was applied between the ZnO film and Pt electrode in the electrolyte solution containing phosphoric acid (4.9×10?5 M), potassium chloride (5.6×10?3 M), and deionized water (150 ml). When the ZnO film was used as a cathode, the sheet resistance of the ZnO film was decreased. However, the optical transparency decreased with increasing treatment time. Thus, the direction of the current flow was changed every 60 s (repetitive electrochemical treatment). The O/Zn ratio and transparency of the ZnO film were kept by the repetitive electrochemical treatment. The sheet resistance depended on the direction of the current flow. When the ZnO film was used as a cathode, the sheet resistance decreased. On the other hand, when the ZnO film was used as an anode, the sheet resistance increased. The sheet resistance of the ZnO films annealed in H2 showed large changes for the repetitive treatment. Defects formed during the H2-annealing possibly caused the enhancement. The optical bandgap of the H2-annealed ZnO films also depended on the direction of the current flow. These results indicate that electrical and optical properties of ZnO films can be modified by the electrochemical treatment.

N.8.23
17:30
Authors : Shan Fei, Han-Sang Kim, Ao Zitong, Tukhtaev Anvar, Dong-Gu Kyung, and Sung-Jin Kim
Affiliations : College of Electrical and Computer Engineering, Chungbuk National University, Cheongju 28644, Korea

Resume : High-performance solution-processed oxide thin-film transistors (TFTs) for large-area display backplane have superior performance, including low cost, high mobility, good environmental stability, and low temperature process ability. We investigated the electrical performance of the IZO TFTs as a function of the spin coating speed. The effect of the spin casting speed on the electrical characteristics as a function of time of the thin-film and oxide IZO TFTs was observed. The structural properties of the IZO thin films are investigated by atomic force microscopy (AFM). An AFM image reveals that the IZO thin-film with a thickness of 1000 rpm and 3000 rpm has an uneven distribution of grains, which deformed the thin film and affects the performance of the IZO TFT. And the IZO thin-film with a thickness of 2000 rpm has a homogeneous and smooth surface with a low RMS roughness of 1.88 nm. In particular, the IZO TFTs exhibit an excellent result, show a field-effect mobility of 3.0(±0.2) cm2/Vs, a high Ion/Ioff ratio of 1.1×10^7, a threshold voltage of 0.4(±0.1) V, and a subthreshold swing of 0.7(±0.01) V/dec.

N.8.24
17:30
Authors : Mitsuaki Yano1, Wataru Kuwagata1, Hiroki Mito1, Satoshi Murakami1, Yuichi Hirofuji1, Yoshiyuki Harada1, Kazuto Koike1, Shintaro Kobayashi2, Katsuhiko Inaba2
Affiliations : 1. Nanomaterials and Microdevices Research Center, Osaka Institute of Technology, Omiya 5-16-1, Asahi-ku, Osaka 535-8585, Japan 2. X-ray Research Laboratory, Rigaku Corporation, Matsubaracho 3-9-12, Akishima City, Tokyo 196-8666, Japan

Resume : Electrochromic properties of c-axis oriented monoclinic tungsten trioxide (m-WO3) epitaxial films were studied by fabricating an electrochromic device operated in a 10 mM aqueous solution of sulfuric acid. The WO3 films were grown on r-plane sapphire substrates by molecular beam epitaxy as described elsewhere [1]. We measured optical transmittance of the WO3 films at the as-grown state, at the protonated state after 4V biasing for 25 min in the solution, and at the deprotonated state after ?4V biasing for 25 min in the solution. At the protonated state, broad and intense transmittance decreases in visible (VIS) and near-infrared (NIR) regions appeared. The decrease in VIS region disappeared at the deprotonated state, however, the decrease in NIR region remained. To disappear the decrease in NIR region, annealing the sample in air at 100 °C for 20 min was effective. When we used amorphous WO3 films for the electrochromic device, on the other hand, both decreases in VIS and NIR regions easily disappeared at the deprotonated state. Therefore, the remaining of the NIR decrease at the deprotonated state might be a characteristic of the epitaxial WO3 films. To analyze the structural change of the epitaxial WO3 films during operation, we measured x-ray diffraction at respective states, and related the protonated and deprotonated states to the formation of hexagonal (h-) HxWO3 tungsten bronze and orthorhombic (o-) WO3·0.33H2O hydrate, respectively. It was also found that both transitions from the m-WO3 to h-HxWO3 and from the h-HxWO3 to m-WO3 were conducted by passing through the formation of o-WO3·0.33H2O. This work was supported in part by JSPS KAKENHI Grant Numbers 16K04936 and 17K06472. [1] M. Yano et al., Appl. Surf. Sci. 381, 2016, pp. 32-35.

N.8.25
17:30
Authors : Imas Noviyana, Annisa Dwi Lestari, Young Woo Heo, Hee Young Lee
Affiliations : Yeungnam University; Yeungnam University; Kyungpook National University; Yeungnam University

Resume : Indium zinc tin oxide (IZTO) thin films with composition corresponding to In:Zn:Sn = 40:50:10 at.% were fabricated on n++ heavily-doped Si wafer using radio frequency magnetron sputering at room temperature under 5% O2/(Ar+O2) ambient. In order to study the application of oxide semiconductor for thin film transistor (TFT) devices, the IZTO thin films were utilized as active channel layer. Bilayer Cu/Ti metal was deposited on the top surface as source/drain electrode. The annealing temperature and IZTO film thickness were varied as an effort to enhance the electrical properties of the TFTs. Annealing treatment for as-deposited IZTO films showed the best TFT device performance at 350°C in air atmosphere as the interface defect concentration was reduced with higher annealing temperature. All IZTO thin films remained amorphous regardless the annealing temperature. The deposition of IZTO thin films were also carried out with thickness varied from 15 nm ~ 150 nm and the films were then annealed at 350°C. The thickness of active channel layer greatly influences the characteristics of the TFTs, and the best characteristics were observed in the transistor device having the channel thickness of 30 nm. It was found that the intrinsic field-effect mobility was independent of the channel thickness and the mobility and subthreshold swing values were sensitive to the channel defects present at the interface between active channel and gate dielectric. The 30 nm-thick annealed IZTO TFT achieved the best device characteristics with a high on/off current ratio of about 2.5×108, a high field effect mobility of 25 cm2/Vs, a low threshold voltage -0.1 V and a very small subthreshold swing of 0.14 V/dec.

N.8.26
17:30
Authors : Jeong-Jin Park1,2, Ho-Yeol Choi1, Chan-Hwa Hong1, Chang-Ho Lee1, Joon-Min Lee1, Byeong-Kwon Ju2* and Woo-Seok Chung1*
Affiliations : 1 Electronics and Telecommunications Research Institute, Korea 2 Display and Nanosystem Laboratory College of Engineering, Korea University, Korea

Resume : There have been many researches on the instability of the SnO phase in p-type SnO TFTs. The p-type transport in tin monoxide occurs only in a very narrow window of deposition process condition. In this study, we tried to widen the process window and enhance the p-type performance by doping aluminum. Al-doping in SnO TFTs could improve the electrical properties such as field effect mobility, subthreshold swing, and threshold voltage.

N.8.27
17:30
Authors : T. Carlier,a A. Ferri,a M.-H. Chambrier,a A. Da Costa,a S. Estradé,b G. Martin,b F. Peiró,b P. Roussel,a R. Desfeux a*
Affiliations : a Univ. Artois, CNRS, Centrale Lille, ENSCL, Univ. Lille, UMR 8181, Unité de Catalyse et Chimie du Solide (UCCS), F-62300 Lens, France. b LENS, MIND-In2UB, Electronics Department, Universitat de Barcelona (UB), Martì i Franquès 1, Barcelona 08028, Spain

Resume : Functional oxides such as lead-free piezoelectrics and ferroelectrics attract an increasing attention in the field of energy correlated with eco-responsible label. In this context, our work was focused on the growth of new environmentally friendly ferroelectric oxides such as Ln2WO6 (Ln = lanthanide). In particular, La2WO6 thin films have been grown on (001)-oriented SrTiO3 substrates by pulsed laser deposition. The structural properties were systematically studied by High Resolution X-ray Diffraction and Transmission Electron Microscopy (TEM). The epitaxial strain stabilization of the high temperature allotropic variety of the material was successfully achieved. Nanoscale piezoelectric and ferroelectric properties were detected into the La2WO6 layer by Piezo-Force Microscopy.[1, 2] As-grown ferroelectric domain patterns were imaged, while domain manipulations and remnant piezoelectric loops measurements have revealed local switching behavior and electromechanical activity. In addition, piezo-/ferroelectric responses were locally detected by an original in situ combination of TEM and Scanning Tunneling Microscopy techniques. These findings pave the way to new eco-responsible multifunctional oxide thin-films dedicated to advanced electronic devices. [1] T. Carlier, M.-H. Chambrier, A. Ferri, S. Estrade?, J.-F. Blach, G. Martín, B. Meziane, F. Peiro?, P. Roussel, F. Ponchel, D. Re?miens, A. Cornet, R. Desfeux. ACS Applied Materials & Interfaces 7, 24409 (2015). [2] T. Carlier, M.-H. Chambrier, A. Ferri, A. Bayart, P. Roussel, S. Saitzek, R. Desfeux. Thin Solid Films 76, 617 (2016).

N.8.28
17:30
Authors : Sae-Young Hong, Hee-Joong Kim, Chan-Yong Jeong, Jong In Kim, Jong-Ho Lee, and Hyuck-In Kwon
Affiliations : 1.School of Electrical and Electronics Engineering, Chung-Ang University, Seoul 156-756, Korea 2.School of Electrical Engineering and Computer Science, Seoul National University, Seoul 151-742, Korea

Resume : We determine the density of interface and bulk trap states in the amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) by using a simple extraction method. The current-voltage curve is measured to determine the bulk trap density, between the source and drain electrodes of the TFT at room temperature under the flat-band condition. In the high voltage region, the carrier transport is well described by the space charge limited current controlled by the bulk trap states that are exponentially distributed in energy with a trap density at the conduction band edge of 6.27 e17 cm-3eV-1 and an inverse slope for the trap distribution of 0.12 eV. The density of traps at the a-IGZO/gate dielectric interface is calculated by subtracting the bulk trap components from the density of total subgap trap states extracted from the subthreshold slope in the transfer curve and the frequency-independent capacitance-voltage characteristics. The experimental results show that the contribution of the interface trap is more significant compared to that of the bulk trap in the subgap density of states of the fabricated a-IGZO TFTs.

N.8.29
17:30
Authors : Kang Eun Lee1, Teahoon Park1, Youngseok Oh1, Moon-Kwang Um1
Affiliations : 1.Carbon composite department, Korea Institute of Materials Science, Changwon, Republic of Korea

Resume : Recently, many research groups have investigated zinc oxide (ZnO) for wide range of applications such as light-emitting diodes, solar cell, UV photodetectors, chemical sensors and transparent electronics. Especially, ZnO nanorod is an excellent UV-sensing material because it has wide band gap (3.34 eV) and prominent photoconductivity when exposed to UV. There are many methods to synthesize ZnO nanorod such as chemical vapour deposition (CVD), hydrothermal synthesis, and solution-processing technique. In this study, we synthesized ZnO nanorods successfully by solution-processing method and controlled the lengths of nanorods by varying the precursor concentration of solutions between 0.5M and 3M in growth step. The morphologies of the nanorods were characterized using scanning electron microscopy (SEM). The crystal structures of the ZnO nanorods were confirmed by X-ray diffractometer (XRD). We fabricated solution-processed ZnO nanorod based UV photodetectors and characterized the sensitivity of the devices with different lengths of ZnO nanorod. The devices showed better UV sensing properties when the lengths of ZnO nanorod are increased.

N.8.30
17:30
Authors : Joshua Wilson, Jiawei Zhang, Aimin Song
Affiliations : School of Electrical and Electronic Engineering, The University of Manchester, UK.

Resume : The effects of semiconductor thickness variations on the current-voltage characteristics of indium-gallium-zinc-oxide (IGZO) Schottky diodes are investigated. Oxide-semiconductors ? particularly IGZO ? have emerged as both an attractive alternative to amorphous-Si for many current applications and as vehicles for the realisation of entirely novel applications, including large area transparent and flexible electronics. Recently, oxide-semiconductor TFTs and Schottky diodes have demonstrated GHz operation ? further confirming their suitability for future electronics. The scalability of TFTs has been well documented ? particularly the short-channel effect ? but there has been very little discussion of the effects of device scalability in Schottky diodes. In published literature on IGZO thin-film Schottky diodes there is a noticeable dependence of the current on the thickness of the semiconductor layer. This phenomenon remains largely undiscussed even though it can cause the reverse current to vary over orders of magnitude. A combination of simulations and experiments has been carried out to demonstrate such an effect and elucidate its origins. Our work indicates that the diodes are diffusion-limited and that that non-uniform Schottky interface properties play an important role in the thickness dependence. These findings may have implications for other device structures employed in large scale thin-film electronics such as Schottky barrier transistors and MESFETs.

N.8.31
17:30
Authors : R. Ratajczak1, C. Mieszczynski1, E. Guziewicz2, S. Prucnal3, M. Stachowicz2 , D. Snigurenko2, K. Kopalko2, B.S. Witkowski2, T.A Krajewski2, W. Skorupa3 and A.Turos4,1
Affiliations : 1 National Centre for Nuclear Research, A.Soltana 7, 05-400 Otwock-Swierk, Poland 2 Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw, Poland 3 Helmholtz Zentrum Dresden ? Rossendorf, Bautzner Landstraße 400, 01328 Dresden, Germany 4 Institute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw, Poland

Resume : Because of its promising potential for applications ZnO has been widely studied recently by many authors. It is expected that implantation of different RE ions can be used for fabrication of white light emitters. In this, the epitaxial thin ZnO films grown by Atomic Layer Deposition were implanted with Er, Pr, Tb, Dy, Eu and Yb to fluence of 5E14 /cm2 and subsequently annealed by RTA. The optical and structural studies were performed by PL and RBS/c, respectively. Our results have shown that two groups of defects are present in our samples: post-implanted defects and native defects. Both play an important role for the luminescence in the visible region. The latter's are present before implantation and after annealing the optical activation of them occurs. RTA leads also to the removal of the defects formed in ZnO during ion implantation along with optical activation of REs. As noted, presence of REs in the structure is influencing the shape of the PL spectrum, unexpected. It means, that we are observing not only sharp lines related to RE emission with characteristic color and broad peaks from native defects, but also peaks originated from complexes related to RE and annealing atmosphere. Interestingly, the different RE implanted ions in a different manner are modeling the shape of the PL emission. Because of applications reasons the color temperature seems most important and we decided to use NBE blue emission with green light originated from native defects combined with the other emissions related with RE for the fabrication of the white light source. This work was supported by the Polish National Centre for Research and Development (NCBiR) through the project PBS2/A5/34/2013 and project by Helmholtz Zentrum Dresden-Rossendorf (HZDR) in the frame of the program: Access to Infrastructure (16000696-ST)

N.8.32
17:30
Authors : B.A. Orlowski1, M. Galicka1, K. Gwozdz2, K. Kopalko1, S. Chusnutdinow1, M.A. Pietrzyk1, P. Caban1, R.H. Schifano, E. Przezdiecka, E. Guziewicz1, E. Placzek-Popko2, B.J. Kowalski1
Affiliations : 1Institute of Physics, PAS, Al. Lotnikow 32/48, 02-668 Warsaw, Poland 2 Department of Quantum Technologies, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370, Wroclaw, Poland

Resume : The paper presents illumination intensity spectra measured for the selected semiconductors photojunctions based on Si(p/n), GaAs, CdTe, ZnTe and ZnO. The illumination intensity spectra were measured with application of lasers sources of selected wave length and intensity to generate carriers in selected crystal components of junction. The used model predicts smooth continuous scan of quasi Fermi level energy in the related band gap region. The ?defect states? located in the forbidden gap within the junction region disturb this continuous scan. Comparison of the spectra measured and proposed by a model allows to determine values of parameters describing distinguished elements of a structure of photovoltaic open circuit intensity spectra. The one kind of differences illustrates the influence of light scattered on introduced crystalline and surface defects. The second difference shows the characteristic decrease of VOC value. This can be caused by electronic defects causing the decrease of minority carriers density of steady states concentration and lowering the energy distance of quasi Fermi level energy from the thermal equilibrium Fermi level. This effect of electrons interaction lowers the minority carriers density and corresponding to it VOC. The used method allows to estimate the binding energy position of the defect levels. [1] H.Y. Fan, Phys.Rev.75, 1631 (1949). [2] B.A. Orlowski at.al Acta Phys.Pol, 129, (2016) A-100.

N.8.33
17:30
Authors : Nur K?c?r1, Ahmet Emin Topal2, Güne? Kibar3, Aykutlu Dana2, Tunç Tüken1
Affiliations : 1. Chemistry Dept., Science & Arts Faculty, Çukurova University, 01330, Adana, Turkey 2. UNAM Institute of Materials Science and Nanotechnology, Bilkent University, 06800, Ankara, Turkey. 3. Department of Materials Engineering, Adana Science and Technology University, 01180, Adana, Turkey

Resume : Surface enhanced Raman spectroscopy (SERS) has been attracted much attention within the scientific community as a powerful analytical method in detection ultra-low concentration of chemical and biological species. Although it is an important technique, there are still many limitations to the commercialization of this technique like being disposable in especial SERS substrates made of noble metals. For this reason, there is a need to develop SERS surfaces with high sensitivity, uniformity, reproducibility, stability and low cost for practical applications and research. In recent years, there have been many research to improve the properties of SERS substrate. In particular, due to the high charge transfer rates, the investigation of using various semiconductors (ZnO, TiO2, Fe2O3, CuO, etc.) as the SERS surface have increased inevitably. Among these semiconductors, zinc oxide (ZnO) with controllable morphology and adjustable the band gap has been considered as promising SERS material. However, it is clear that there is a need for extending the knowledge about usage these materials in SERS application. The studies showed that nano-metric roughness of these noble metals significantly affected the intensity of SERS signal. The aim of this study, investigating the SERS properties of silver (Ag) coated ZnO nanostructured surfaces fabricated on ITO glass. For this purpose, 3D nanostructured ZnO films were synthesized in three different morphology nanorods, nanoplates and nanoflowers by electrochemically. Subsequently, Ag nanoparticles was deposited onto ZnO surfaces to increase the detection sensitivity. The surface morphology and crystallographic properties of prepared ZnO nanostructures films in 3 morphologies were characterized by FE-SEM and XRD analysis. The SERS performance and properties of this Ag coated ZnO nanostructured films were evaluated with using methylene blue (MB) as test molecule. The sample solutions containing MB were added dropwise onto newly fabricated in three different morphologies for the detection. The SERS measurements were performed in Alpha 300 Raman microscope using a laser source at 532 nm and with an excitation power of 100 µW. The angle of the light is 900. All Raman spectra were measured at 20 scans with integration time of 0.1 second over a range from 0 to 3500 cm-1. These hierarchically nanostructured hybrid surfaces exhibited SERS signals of MB demonstrates that Ag coated ZnO nanostructures on ITO can be used as an active SERS surface with high sensitivity and reusability in practical applications.

N.8.34
17:30
Authors : Güne? K?BAR1,2 , Ahmet Emin Topal3, Aykutlu Dana3, Ali Tuncel2,4
Affiliations : 1 Department of Materials Engineering, Adana Science and Technology University, 01180, Adana,Turkey 2 Bioengineering Division, Hacettepe University, 06800, Ankara, Turkey 3 UNAM Institute of Materials Science and Nanotechnology, Bilkent University, 06800, Ankara, Turkey 4 Division of Nanotechnology and Nanomedicine, Hacettepe University, 06800, Ankara, Turkey

Resume : Surface Enhancement Raman Spectroscopy (SERS) has growing interest in scientific researches for the detection of trace molecules. Basically, the noble metals such as gold, silver and others were used to obtain the SERS signal. The aim of the study the rough silver metal based shell over the monodisperse-porous poly(mono-2-(methacryloyloxy) ethyl succinate-co-glycerol dimethacrylate) (poly(MMES-co-GDMA)) microparticles 5 mm in size was constructed by seed-mediated growth technique. Monodisperse-porous poly(MMES-co-GDMA) microbeads were synthesized using a modified staged shape template polymerization. The magnetization of the microbeads was achieved by the generation of magnetic hematite nanoparticles within the polymer microbeads using their carboxyl functionality. Magnetic particles were then refluxed with 3-aminopropyl) triethoxysilane (APTES) in toluene for the attachment of primary amine functionality onto the magnetic polymer microbeads. The gold seed decoration was carried out via amino group of the magnetic microbeads. Gold seed decorated particles is used for growing a rough silver shell around the magnetic polymer core. The morphology and crystalline form of the SERS substrate were characterized by SEM, XRD. Magnetic behavior of the material was determined by VSM. The surface morphology of this newly synthesized material gives an opportunity to detect just 1 µl of any SERS active sample at sub-micro molar concentrations. The stability, reproducibility and high detection limits by using limited sample creates the idea of detecting drugs at very low concentrations particularly important for forensic science or environmental health. The successful results were obtained for 10-8M antibiotic detection and its commercial product also the quantitative calibration curve showed the strength of this technique.

N.8.35
17:30
Authors : David Lehninger1, David Rafaja2, Julia Wünsche1, Frank Schneider1, J. von Borany3, and Johannes Heitmann1
Affiliations : 1 TU Bergakademie Freiberg, Institute of Applied Physics, D-09596 Freiberg, Germany.; 2 TU Bergakademie Freiberg, Institute of Materials Science, D-09596 Freiberg, Germany.; 3 Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, D-01314 Dresden, Germany.

Resume : The stabilization of non-centrosymmetric orthorhombic HfO2 with space group Pbc21 is related to the ferroelectricity of this material [1]. However, this stabilization requires a strict process control [2,3] and/or the application of an encapsulation layer [1]. In ZrO2, the stabilization of this phase has so far only been reported in magnesium stabilized alloys after thermal shocking [4]. Here, we report on the formation of orthorhombic ZrO2 (that can be described with the space group Pbc21) in thin Zr-Ta-O films. Thin Zr-Ta-O films with different tantalum concentrations and a thickness of 500 nm were deposited on silicon wafers by co-sputtering a ZrO2 and a mixed ZrO2/Ta2O5 target. In the as-deposited state, all films were amorphous. After annealing, formation of tetragonal (Zr,Ta)O2 was observed for [Ta]/([Ta] [Zr]) ? 0.19, that of orthorhombic (Zr,Ta)O2 for [Ta]/([Ta] [Zr]) > 0.19. Thin films containing at least as much tantalum as zirconium ([Ta]/([Ta] [Zr]) ? 0.50) decomposed in two orthorhombic phases upon crystallization: (Zr,Ta)O2 and tantalum-rich (Ta,Zr)2O5. The Rietveld analysis of X-ray diffraction patterns revealed that the crystal structure of (Zr,Ta)O2 can be described with the non-centrosymmetric space group Pbc21. The broad range of tantalum concentrations in which orthorhombic (Zr,Ta)O2 is formed as a single crystalline phase, is promising for the use of this compound in ferroelectric field effect transistors. [1] T. S. Böscke et al., Appl. Phys. Lett. 99, 102903 (2011). [2] T. Olsen et al., Appl. Phys. Lett. 101, 82905 (2012). [3] M. Hoffmann et al., J. Appl. Phys. 118, 72006 (2015). [4] E. H. Kisi, C. J. Howard, and R. J. Hill, J. Am. Ceram. Soc. 72, 1757 (1989).

N.8.36
17:30
Authors : Bojana Vi?i?, Luka Pirker, Janez Kova?, Sre?o ?kapin, Maja Rem?kar
Affiliations : Jozef Stefan Institute, Ljubljana, Slovenia

Resume : Nonstoichiometric phases of the WO3 compound, i. e. in the form of WO3-x, attracted a lot of interest due to their well-defined phases and distinctive morphological structure. For x=0.1 (WO2.9 or W20O58), this compound undergoes metal-insulator transition in bulk. For x>0.1, (WO2.72 or W18O49, WO2.8 or W5O14, WO2.83 or W24O68), the electrical and optical properties are dominated by free electrons in bulk. At the nanoscale, these suboxides can be found as nanoplates, nanowires1 and nanoparticles. We report on suboxide nanotiles produced with high yield. Their width ranges from couple of hundreds of nm to 2 µm, while the lenght spans from a 1 to several µm. WO3-x nanotiles have been characterized with electron microscopy (SEM and TEM) and various spectroscopic methods, such as XRD, XPS, Raman and UV-Vis spectroscopy, in order to determine their phase and structure.

N.8.37
17:30
Authors : Martin Schwellberger Barbosa(1,2), Fernando Modesto Borges de Oliveira(1), Xiang Meng(2), Clara Santato(2), Juan Carlos Gonzalez(3), Marcelo Ornaghi Orlandi(1)
Affiliations : 1. UNESP, Araraquara, SP, Brazil.; 2. Montreal Polytechnique, Montreal, QC, Canada.; 3. UFMG, Belo Horizonte, MG, Brazil

Resume : Tungsten trioxide (WO3) is an n-type semiconductor (Egap = 2.6 eV) presenting great potential for applications in gas sensors, solar cells, photocatalysis and transistors. WO3 films were shown to be electrochemically active on aqueous (acidic) and non-aqueous (LiClO4 dissolved in propylene carbonate) solutions with reversible oxidation/reduction behaviour on voltammetric measurements, enabling them to be used as electrolyte gated transistors (based on the use of electrolytes as the gating medium). Three different types of WO3, fabricated using different synthesis procedures, were considered as transistor channel materials in this work. Granular hexagonal WO3 films were prepared by sol-gel method, and WO3 hexagonal nanofibers were synthetized in-situ on substrates with pre-deposited granular WO3 films (seed layer) using a hydrothermal procedure. WO3 monoclinic nanoplates, in powder form, were obtained by microwave-assisted hydrothermal method, and the powder was film deposited by spin coating, followed by heat treatment at 400 oC for 2 hours for organic removal. Electrolyte-gating was performed using an ion-gel composed of triblock copolymers (poly (styrene-ethyleneoxide-styrene)) and ionic liquids (such as [EMIM][TFSI]) and a high surface area carbon top-gate electrode. Different values of the charge doping density and charge carrier mobility were expected for the three types of transistor channels and results were discussed in function of material morphology and film density.

N.8.38
17:30
Authors : P.H. Suman (1,2), M.S. Barbosa (1), H.L. Tuller (2) and M.O. Orlandi (1)
Affiliations : (1) Department of Physical-Chemistry, São Paulo State University, Araraquara, SP 14800-060, Brazil. (2) Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

Resume : SnO2 is a well-consolidated industrial sensor material used to detect a wide range of flammable and toxic gases. However, recent results show that one-dimensional (1D) Sn3O4 structures emerge as unusual alternative building blocks for the fabrication of next-generation sensor devices composed of a single structure or to create p-n junctions with other oxides. In this work, the gas sensor properties of pristine and metal-decorated Sn3O4 nanobelts are presented. Sn3O4 nanobelts were synthesized by carbothermal reduction method and catalyst metal nanoparticles (Pt, Pd and Ag) were prepared by Polyol method. Surface functionalization of the nanobelts was achieved by coating the structures with 1wt% of metallic nanoparticles. Differences in the gas sensing features of the multiple samples were observed after exposures to different concentrations of NO2, H2, CO and CH4 (1-1000 ppm) and their properties (sensitivity and selectivity) were altered by the surface modification. This effect can be attributed to the role of metal nanoparticles which act as catalysts in the interaction of the oxide with reducing gases and as deactivators in the interaction with oxidizing gases, suggesting that chemical or electrical sensitization took place. Furthermore, the sensitivity of materials was found to be highly dependent on the operating temperature of sensors. Impedance Spectroscopy was used to further investigate those processes and a model for the effects of metal catalysts could be proposed.

N.8.39
17:30
Authors : P.H. Suman (1), H.L. Tuller (2) and M.O. Orlandi (1)
Affiliations : (1) Department of Physical-Chemistry, São Paulo State University, Araraquara, SP 14800-060, Brazil. (2) Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

Resume : Several approaches have been used to optimize and improve the gas detection properties in metal oxide semiconductors, either by chemical or morphological modifications or by optimization of operating conditions. Studies have pointed out that the formation of p-n junction can significantly improve the sensing performance due to the increase of defect sites at the interface region. In this work, we present the effects of p-n junctions on the gas sensor response of SnO2-CuO nanofibers in comparison to the pristine SnO2, both prepared by the electrospinning method. XRD and TGA showed that after annealing at 500 °C, crystalline and free of impurities materials were obtained. FE-SEM and TEM were used to analyze the crystallinity and the morphological characteristics of the fibers after the annealing. EDS and XPS techniques confirmed the chemical composition of the grown structures as well as the distribution of the chemical elements in the structures. AFM and specific surface area measured by the BET method revealed that the surface roughness and surface area of the fibers depending on their chemical composition. From the gas sensor characterizations, it was found that the sensor responses of both materials are highly dependent on the concentration of NO2, H2, CO and CH4 and the operating temperature. SnO2 fibers exhibited higher sensing response to NO2, while the SnO2-CuO fibers presented higher sensitivity to H2, showing the importance of junctions for the sensor properties.

N.8.40
17:30
Authors : D. Spassov, T. A. Krajewski, A. Paskaleva, E. Guziewicz, G. Luka, Tz. Ivanov
Affiliations : Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia 1734, Bulgaria; Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland

Resume : In this work dielectric and electrical properties of Al2?3/HfO2 multilayer stacks obtained by atomic layer deposition in dependence on the thickness of Al2?3 and HfO2 layers and the post-deposition annealing (PDA) in different ambient (O2, N2, air) have been investigated in terms of their application as trapping layers in emerging charge-trapping non-volatile flash memories. It is found that O2 and N2 PDA have distinctly different influence on electrically active defects in the stacks - N2 introduces negative charges whereas O2 ? positive ones. Three different processes give rise to hysteresis effects: 1) trapping of electrons under positive gate bias; 2) trapping of holes under negative gate bias. These are the useful processes which define the memory window. The third process is the generation of positive charge under high electric field stress which degrades the stacks and results ultimately in breakdown. The results unambiguously show that PDA in O2 enhances the charge storage ability of the stacks and anneals defects in HfO2 which are precursors of stress-induced positive charge. Negligible memory window is observed for samples annealed in N2 or air. The as-deposited stacks are more susceptible to stress-induced positive charge generation. The results imply that the charge storage ability of Al2?3/HfO2 stacks could be tailored by optimization of stack parameters as well as annealing processes. Acknowledgements: The work was financially supported by EC in the frame of project INERA REGPOT 316309.

N.8.41
17:30
Authors : A.K. Manna, Puspendu Guha, S. Srivastava , B.P. Bag and Shikha Varma
Affiliations : Institute Of Physics, Bhubaneswar, 751005, India ; Institute Of Physics, Bhubaneswar, 751005, India ; Indian Institute Of Technology, Kharagpur, 721302,India; Colloids & Material Chemistry Department, IMMT, Bhubaneswar, 751005, India; Institute Of Physics, Bhubaneswar, 751005, India .

Resume : In recent years, there has been an extensive attention towards the development of enzymless amperometric glucose sensors due to its high stability and repeatability compared to enzyme-based glucose biosensors. CuO has been investigated as an enzymeless glucose sensor due to its high chemical activity, nontoxic nature and outstanding redox behavior. On the other hand ZnO is also a good functional material in glucose sensing area as it possesses nice biocompatibility and fast electron transfer ability between the active sites and the electrodes. We have synthesized Zn(Cu)O composite structures through electrodeposition technique. The structure and morphology of the samples were characterized using XRD & FESEM . XPS and Raman studies confirm the presence of specific copper related phase. These composite structures display glucose sensing . The optical properties of these structures have also been investigated. Results show band gap tailoring of these structures.

N.8.42
17:30
Authors : Matthew Zervos (a), Eugenia Vasile (b), Eugeniu Vasile (c), Andreas Othonos (d)
Affiliations : (a) Nanostructured Materials and Devices Laboratory, University of Cyprus, Nicosia, 1678, PO Box 20537, Cyprus (b,c) Politehnica University of Bucharest, 313 Splaiul Independentei, Bucharest, 060042, Romania (d) Laboratory of Ultrafast Science, Department of Physics, University of Cyprus, Nicosia, 1678, PO Box 20537, Cyprus

Resume : Metal oxide semiconductor nanowires (NWs) such as SnO2, In2O3 etc have been investigated extensively in the past for the fabrication of nanoscale devices. These are n-type wide band gap semiconductors and have relatively low carrier densities of the order of 1016 cm-3 as we have shown previously for SnO2 NWs grown by the vapor liquid solid mechanism [1]. Consequently they require doping to increase their conductivity and improve the performance of devices. In the past Sb doped SnO2 NWs with metallic conductivity have been obtained but recently Ma et al [2]. showed that a substantial band-gap tuning and a strain-controlled, semiconductor to gapless semimetal transition, is possible via the incorporation of Pb in SnO2. However no one has investigated Pb doping of SnO2 NWs. In contrast PbO2 is a narrow energy band semiconductor with metallic like conductivity due to oxygen vacancies, which form a donor state, resonant in the conduction band but more importantly PbO2 has a tetragonal rutile crystal structure with a = 0.491 nm and c = 0.3385 nm which are close to the lattice constants of tetragonal rutile SnO2 i.e. a = 0.4737 nm and c = 0.318 nm, so they differ only by 3%. This means that PbO2 could be grown on SnO2 or form the ternary oxide PbxSn1-xO2. Recently Ganose et al [3] carried out detailed theoretical calculations and found that the energy band gap and work function of SnO2 may be tailored by alloying it with PbO2 in order to improve its transparency and conductivity. Here we describe our latest work on (a) Pb doping of SnO2 NWs as well as the growth of PbxSn1-xO2 NWs and (b) the growth of PbO2/SnO2 core-shell NWs. A high yield uniform distribution of SnO2 NWs with diameters of 10 to 100 nm's and lengths up to 100 um can be readily obtained by the VLS mechanism at 800C and 0.1 mBar on Si, metal foils such as Ni and Mo but also C fibers using Au as a catalyst. The SnO2 NWs have a tetragonal rutile crystal structure and an n-type carrier density of 1016 cm-3 due to donor like states related to oxygen vacancies. We show that Pb doping of SnO2 NWs is not possible via the VLS mechanism at 800C. In other words the Pb can not be incorporated into the SnO2 probably due to the large difference in the radii of Sn and Pb but we observe a complete suppression of the one dimensional growth of the SnO2 NWs due to the small surface tension of Au:Sn:Pb nanoparticles for high contents of Pb. It is not surprising then that PbSnO2 NWs can not be obtained at 800C since its binary consistuent components i.e. SnO2 and PbO2 can not be grown under identical conditions, primarily due to the fact that PbO2 has a low melting point of 300C. To the best of our knowledge only Pan et al [4] has obtained PbO2 nanobelts at low temperatures that were not explicitly specified and by using PbO at 900 C . Here we show that PbO2 NWs may be obtained without a catalyst by the reaction of Pb and O2 between 100C to 300C and 0.1 mBar which allows the formation of droplets that are necessary for one dimensional growth and the incorporation of Sn. Another way of improving the conductivity of SnO2 NWs is the growth of a SnO2/PbO2 core-shell NWs in view of the fact that their lattice constants differ only by 3%. We show that this is feasible only via the deposition of PbO2 from solution at room temperature and describe the structural, optical and electronic properties such as the charge distribution and potential profile of both SnO2/PbO2 and SnO2/PbO core-shell NWs in the context of energy conversion and storage. [1] Tsokkou D, Othonos, A and Zervos M 2012 Carrier Dynamics and Conductivity of SnO2 Nanowires Investigated by THz Conductivity Spectroscopy Appl. Phys. Lett. 100,133101-1. [2] F.Ma, Y.Jiao, G.Gao, Y.Gu, A.Bilic, S.Sanvito and A.Du, Substantial Band-Gap Tuning and a Strain-Controlled Semiconductor to Gapless/Band-Inverted Semimetal Transition in Rutile Lead/ Stannic Dioxide, ACS Appl. Mater. Interfaces, 2016, 8, 25667?25673. [3] A.M.Ganose and D.O.Scanlon, Band gap and work function tailoring of SnO2 for improved transparent conducting ability in photovoltaics, J. Mater. Chem. C, 2016, 4, 1467. [4] Z.W.Pan, Z. R.Dai, and Z. L.Wang, Lead oxide nanobelts and phase transformation induced by electron beam irradiation, Appl.Phys.Lett., 2002, 80, 309.

N.8.43
17:30
Authors : K. Chernyakova*, I. Vrublevsky*, D. Rutkauskas**, R. Karpicz**
Affiliations : *Belarusian State University of Informatics and Radioelectronics, P. Brovka, 6, Minsk, Belarus **Center for Physical Science and Technology, Savanoriu 231, Vilnius, Lithuania

Resume : ?-Al2O3 specimens (144 ?m thick) by the heat treatment at 1400 °C of free-standing sulfuric acid anodic alumina were obtained. Scanning electron microscopy analysis shows that the as-anodized anodic alumina films possess well-ordered porous structure with the pore diameter of about 10.2 nm. After heat treatment at 1400 °C the samples lose their porous structure and certain crystallites with average size of 2?6 ?m can be observed. These crystallites can be visualized by fluorescence imaging. According to differential scanning calorimetry data accomplished by X-ray analysis, the first step of crystallization occurs at around 967 °C, producing ?-Al2O3. The second one takes place at around 1194 °C, which corresponds to the formation of ?-Al2O3. Both the as-anodized and 1400 °C-treated anodic alumina samples possess the fluorescence in the wavelength range 400 700 nm with maximum at around 450 nm.

N.8.44
17:30
Authors : Hemraj M. Yadav, Shielah Mavengere, Jung-Sik Kim
Affiliations : University of Seoul

Resume : The coupling of TiO2 with graphene can lead to enhanced electronic and photocatalytic properties of TiO2 because the graphene can lower the recombination of electron-hole pairs, enhancing the charge transfer rate of electrons and surface adsorption of target gaseous or organic pollutants. In this study, anatase TiO2-graphene oxide (GO) nanocomposites with different GO loadings were prepared by a solvothermal method. The prepared photocatalyst were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infra-red spectroscopy (FTIR), and photoluminescence spectroscopy (PL). The XRD results confirmed the anatase phase of TiO2 in the composites and Raman analysis revealed the presence of GO in the nanocomposites. TEM studies indicated the uniform dispersion of TiO2 NPs on the GO surface with slight aggregation. The photocatalytic performance of the prepared nanocomposites was evaluated by the degradation of gaseous benzene under UV light irradiation. Anatase TiO2-GO nanocomposites exhibits better photocatalytic performance than pure TiO2 nanoparticles (NPs). The apparent photocatalytic reaction rate constant of 0.25wt% GO-loaded TiO2 nanocomposites(GOT-0.25) is about 3 times higher than that of pure anatase TiO2 NPs. Especially, the GOT-0.25 exhibit high photocatalytic activity compared to anatase TiO2 under UV light, likely due to the effective separation of photogenerated charges. The anatase TiO2-GO nanocomposites facilitate the separation of photogenerated charge carriers along with high stability, which ultimately enhance the photocatalytic activity under ultraviolet irradiation.

N.8.45
17:30
Authors : M. Guziewicz (1), M. Wzorek (1), K. Golaszewska (1), M. My?liwiec (2), G. Luka (3), D. Snigurenko (3), J. Domagala (3), E. Guziewicz (3)
Affiliations : 1) Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw, Poland 2) Institute of Microelectronics and Optoelectronics, Warsaw University of Technology Ul. Koszykowa 75, 00-662 Warszawa, Poland, 3) Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland

Resume : Titanium dioxide is still a promising wide bandgap material for optical coating, gas sensors, optoelectronic and photo-electrochemical applications. TiO2-based photocatalysts have been interesting for their high solar-energy conversion efficiency. Higher efficiency of photo-activated processes is observed for crystalline TiO2 in the anatase phase, which is characterized by a wider band gap and reveals semiconducting properties. We present results for TiO2 films deposited on a (0001) sapphire substrate by reactive magnetron sputtering and atomic layer deposition (ALD). The films were doped with Nb or N to increase electrical conductivity. Pulse dc reactive co-sputtering was performed from Ti and Nb target in a O-Ar or O-N-Ar gas mixture, at total pressure of 0.004 mbar and at substrate temperature up to 600 C deg. ALD films were formed with TiCl4 and H2O precursors at 220 C deg. Highly oriented anatase (112) nanocrystalline TiO2 films were received by the sputtering method at temperature in range of 400 ? 600 C deg., while the ALD films apart from the anatase contain admixture of the rutile phase. Undoped and Nb doped TiO2 films are highly transparent (70-80 %). The bandgap of 3.79 eV for the sputtered TiO2 film increases to 3.87 eV for the TiO2?x:Nb film with a 19% at. Nb content, while the bandgap of 3.7 eV was observed for the ALD TiO2 film. Photoluminescence spectra of the TiO/2?x/:Nb films measured at 5K reveal UV emission peaks and a broad peak in range of 440 - 740 nm. The lowest resistivity of 70 m-ohm-cm was recorded for the TiO/2?x/ ALD film doped with 2 at.% of Nb. The work was partially supported by the European Regional Development Fund, through the Innovative Economy grant "MIME" (POIG.01.01.02-00-108/09).

N.8.46
17:30
Authors : R. Ratajczak1, G. ?uka2, E. Guziewicz2, S. Prucnal3, A. Stonert1, D. Snigurenko2, A. Turos4
Affiliations : 1National Centre for Nuclear Research, ?wierk, Poland 2Institute of Physics, Polish Academy of Sciences, Warsaw, Poland 3Helmholtz Zentrum Dresden ? Rossendorf, Dresden, Germany 4Institute of Electronic Materials Technology, Warsaw, Poland

Resume : ZnO doped with Rare Earth (RE) have been widely investigated because of possible application in optoelectronics. Ion implantation is a convenient technique for introducing RE ions into the material, because dopant concentration and its depth profile can be easily controlled. However, the ballistic nature of the implantation process leads to the damage of a crystal lattice, so a high temperature post-growth annealing is required for crystal structure recovery and activation of optical emission. Unfortunately, the side effect of a high-temperature annealing is displacement of RE ions from substitutional to interstitial sites and out-diffusion of RE to the surface, where they are no longer optically active. In the paper we present an attempt to overcome this problem by placing an additional ZnO cap layer at the top of implanted ZnO:Yb films. Epitaxial ZnO/GaN films were implanted with Yb ions to a fluence of 1x1015 and 3x1015 at/cm2. After implantation, a 30 nm thick cap ZnO films was grown by ALD prior to post-growth Rapid Thermal Annealing, which was performed at temperature 900 and 1000oC. We found out that for lower fluence an additional cap ZnO layer considerably enhances the photoluminescence intensity, especially in the visible spectral region. The work was supported by the Polish National Centre for Research and Development (NCBiR) through the project PBS2/A5/34/2013 and by the Helmholtz Zentrum Dresden-Rossendorf (HZDR) program Access to Infrastructure (15000594-ST).

N.8.47
17:30
Authors : German Telbiz, Natalia Romanovska, Eugen Leonenko, Petro Manoryk
Affiliations : L.V.Pisarzhevsky Institute of Physical Chemistry NASU, 31 Nauki av., Kyiv 03028;

Resume : The proton conducting membranes fuel cells for various applications, which employ polymer Nafion membranes, yield the best performance around 80oC. The operation of fuel cells at this temperature has a number of shortcomings which can be avoided by raising the temperature to 120°C and even higher. However, Nafion membranes experience a rapid drop in conductivity as temperature increases to above 100°C, and not suitable for high-temperature operation. There is, therefore, a demand for membranes which can operate in the temperature range up to 200°C. In this context, the improvement of the existing membranes are pursued, namely composite membranes consisting from Nafion, and inorganic nanoparticles are considered. In this study, we specifically focus on the effect of careful doped TiO2 nanoparticles on the performance of the Nafion/TiO2 composite membranes in high temperature. In the framework of the research by XPS, SEM, XRD, TPD-MS, optical and vibrational spectroscopy is investigated the properties of modified titanium oxide and composite polymer membranes. Effect of concentration of proton generation additions on the total and specific proton conductivity of composite polymer membranes depending on the concentration of proton-generating additives and relative humidity had been estimated. Established, that modified titanium oxide nanostructures have an enhanced capacity for coordination of water molecules on the surface, causing the formation of the grid of hydrated structures with labile protons that maintenance of structures percolation cluster hydrophilic channels in membranes. The conductivity of the Nafion/TiO2 composite ?an is a consequence the formation of a percolation cluster, as result of mesoscopic ordering and polarization of water molecules on the strong acid groups of doped titanium dioxide species to form hydrated. Preliminary tests of proton conductivity (the direct injection of protons) that was carried out on the composite membrane, has highlighted the benefit of doped titania nanocomposites introduction on the conductivity in the temperature range up to 240° C, that maintained at (10-3-10-5 S), compared to the commercial Nafion membrane.The above may be a prerequisite for effective function of composite polymer membrane in conditions close to the operating conditions of fuel cells.

N.8.48
17:30
Authors : Sakir Aydogan and Mehmet Y?lmaz
Affiliations : S.Aydogan 1-Advanced Materials Research Laboratory, Department of Nanoscience and Nanoengineering, Graduate School of Natural and Applied Sciences, Ataturk University, 25240, Erzurum, Turkey 2 Department of Science Teaching, Faculty of K.K. Education, Atatürk University, 25240 Erzurum, Turkey 3-Physics Department, Science Faculty, Ataturk University, 25240, Erzurum, Turkey Environment Department, Engineering Faculty, Ardahan University, 75000, Ardahan, Turkey Mehmet Yilmaz Advanced Materials Research Laboratory, Department of Nanoscience and Nanoengineering, Graduate School of Natural and Applied Sciences, Ataturk University, 25240, Erzurum, Turkey

Resume : Facile growth of ZnO films: the effect of La doping S.Aydogan1* and M. Yilmaz1,2, 1Advanced Materials Research Laboratory, Department of Nanoscience and Nanoengineering, Graduate School of Natural and Applied Sciences, Ataturk University, 25240, Erzurum, Turkey 2 Department of Science Teaching, Faculty of K.K. Education, Atatürk University, 25240 Erzurum, Turkey *Physics Department, Science Faculty, Ataturk University, 25240, Erzurum, Turkey *Environment Department, Engineering Faculty, Ardahan University, 75000, Ardahan, Turkey *saydogan@atauni.edu.tr Generally, indium (In) doped tin oxide (ITO) is widely used in optoelectronic applications where a transparent conductor is required. Due to the fact that the main constituent of ITO is In, which has been listed among the critical raw materials by the EU, it has been become compulsory to search for alternative materials instead of ITO. However, some problems such as poor stability, difficulty of preparation and limited natural reserves of In, restrict its utilization for device applications. At present, metallic films and metallic oxide films are mainly used as transparent conductive oxides (TCO). Among them, ZnO takes an important role as TCO because of its excellent photoelectric, piezoelectric, dielectric properties and easy dope characteristic. In this context, we can say that characteristic properties of ZnO can be easily changed by using different dopant. The difference between ionic radius of zinc or oxygen and dopant materials affects the characteristics of ZnO. In this study, La-doped ZnO films were prepared via chemical spray pyrolysis technique and its device performances were investigated as a function of La content.

N.8.49
17:30
Authors : Edita Vernickait?, Pavel Globa, Henrikas Cesiulis, Natalia Tsyntsaru
Affiliations : Vilnius University, Naugarduko str. 24, Vilnius, Lithuania; Institute of Applied Physics of ASM, Academiei str. 5, Chisinau, Moldova; Vilnius University, Naugarduko str. 24, Vilnius, Lithuania; Institute of Applied Physics of ASM, Academiei str. 5, Chisinau, Moldova

Resume : Anodic aluminum oxide (AAO) template has gained increasing importance in recent years due to its potential industrial and technological applications for nanometric device fabrication incorporating electrodeposition, such as nanorods, nanotubes and nanowires [1]. In this study AAO membrane on the surface of aluminum alloy (AA 1050) sheet was fabricated in sulfuric acid solution using a two-step anodization process [2]. Cross-sectional and top-view SEM images showed that obtained pores are straight and extend throughout the entire thickness of the oxide (~ 6 µm). The diameter of the nanowires was measured to be about 25 nm and the porosity of self-ordered anodic alumina - around 20 %. The porous alumina is separated from the Al alloy by thick nonoporous barrier layer (~ 26 nm). In order to improve the conductivity for electrodeposition process, barrier oxide layer has been thinned up to ~ 10 nm after the treatment in the same solution as for anodization at 30 °C under potentiostatic conditions (E = -1 V). Electrodeposition of Co-7 at.% W nanowires has been carried out with a pulse mode in a solution of 120 g/l CoSO4, 60 g/l CoCl2, 30 g/l boric acid and 2 g/l polyethylene glycol 600 (pH 5, 22°C). The pulse mode consisted of a constant current pulses of - 60 mA/cm2 and 0.3 mA/cm2 for 1 ms and 4 ms, respectively. Fabricated nanowires were uniform, independent, parallel to each other and their density was close to the pores density of the original AAO. Heat treatment has been used to obtain highly active cobalt oxide catalysts (CoO and Co3O4) and catalytic performance of fabricated nanowires into AAO has been performed. [1] N. Tsyntsaru et al., Electrochimica Acta 188 (2016) 589?601.

N.8.50
17:30
Authors : Piotr Nowak (a) ; Wojciech Maziarz (a) ; Kazimierz Kowalski (b) ; Katarzyna Zakrzewska (a)
Affiliations : (a) - Faculty of Computer Science, Electronics and Telecommunications, AGH University of Science and Technology, al. Mickiewicza 30, Kraków, Poland ; (b) - Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, Kraków, Poland

Resume : Titanium dioxide is one of the metal oxides used in gas sensors because of significant changes in the electrical properties of TiO2 as a result of interaction with both reducing and oxidizing gases. PVD methods are most widespread in the thin films preparing, however Langmuir ? Blodgett (LB) is emerging technique [1] which allows to obtain TiO2 ultra-thin films at room temperature. This method is successfully used for the preparation of organic monolayers [2], as well as for other metal oxides, e.g. SnO2 [3]. TiO2 thin films were obtained using Langmuir KSV NIMA trough. TiO2 solutions were prepared using powders (rutile, anatase) and liquid precursor TTIP (titanium tetraisopropoxide). A mixture of chloroform and ethanol was used as a solvent for TiO2 powders (suspension with concentration c = 0.5 mg/ml) and chloroform for TTIP (clear solution, c = 0.48 mg/ml). TiO2 thin films were deposed on amorphous silica - SiO2, Al2O3 ? ceramic, specially dedicated to sensor measurements BVT substrates. UV-VIS spectroscopy, XPS and XRD methods showed the presence of TiO2 on the coated surface. Optical profilometry revealed the thickness of TiO2 films was equal to about 60 nm. Moreover, for powder sources local grain deposition was found. A homogeneous monolayer was observed for the TTIP precursor, however the films might be discontinuous. Sample response to NO2 and H2S gases at 50°C revealed acceptable sensitivity and reproducibility. This work was supported by AGH University of Science and Technology Dean?s Grant no. 15.11.230.334. [1] K. Choudhary et al., Langmuir, 31, 1385-1392, (2015) [2] A. Tepore et al., Langmuir, 17, 8139-8144, (2001) [3] S. Choudhary et al., Applied Physics Letters, 89, 071914 (2006)

N.8.51
17:30
Authors : Alessandro Kovtun, Derek Jones, Andrea Liscio, Vincenzo Palermo
Affiliations : ISOF-CNR, Via Gobetti 101, Bologna, Italy

Resume : Graphene-based materials (GRMs) possess a range of different chemical, electronic and electrical behaviors [1, 2, 3]. The control and tuning of their chemical composition is one of the keys for the success of such materials in industrial applications. Despite X-ray Photoemission Spectroscopy (XPS) being one of the most powerful and commonly used techniques to study the chemical analysis of surfaces [4] a quantitative and reliable approach to study GRM is still lacking. For example, there is no standard method for estimating the degree of oxidation of GRM (O/C or C/O ratios). The ratio of the number of carbon and oxygen atoms in bulk materials is often simply given by the intensity ratio of the O 1s and C 1s XPS peaks. This approach can be applied to thin films (< 5 nm thick), with single- or several- layers deposited on oxygen-free substrates, in order to prevent any overestimation of the oxygen present in the sample. Moreover, there are various approaches used for deconvoluting the complex structure of the C 1s spectrum leading to large variations in the estimation of the various carbon oxidation states present in the sample even by factors of 2 or 3 times the measured value [5]. Here, we propose a more reliable protocol to obtain the O/C ratio to determine the chemical functionalization of GRMs using a quantitative line-shape analysis of the C 1s peak based on the Doniach?Sunjic equation and XPS measurements on freshly cleaved Highly Oriented Pyrolitic Graphite. In this way, we can attempt to distinguish the various contributions from: graphitic carbon (sp2), defects (mainly sp3), hydroxyl-, epoxy-, carbonyl- and carboxyl- groups [4]. The proposed protocol was applied to several GRMs with different O/C ratios (between 0.02 and 0.45) and different thicknesses (from 1 to 30 nm) in order to avoid substrate contributions and to check the results with measurements on the corresponding bulk systems. In particular, we have developed a simple method for comparing the results obtained using different models which can discriminate between both under- and over-estimations of the degree of oxidation of GRMs. This approach holds promise for developing a simple general protocol to analyse GRMs on various substrates. [1] William S. Hummers and Richard E. Offeman, JACS 80, 1339 (1958) [2] M. Batzill, Surface Science Reports 67, 83 (2012) [3] Z.Y. Xia et al., Chempluschem 79, 439 (2014) [4] F. Perrozzi et al., Journal of Physical Chemistry C 117, 620 (2013) [5] J.A. Leiroet al., Journal of Electron Spectroscopy and Related Phenomena 128, 205 (2003)

N.8.53
17:30
Authors : H. H. Güllü (a,b,*), Ö. Bayrakl? (b,c,d), M. Terlemezo?lu (b,c,e) and M. Parlak (b,c)
Affiliations : a Central Laboratory, Middle East Technical University, 06800, Ankara, Turkey; b Center for Solar Energy Research and Applications (GÜNAM), 06800, Ankara, Turkey; c Department of Physics, Middle East Technical University, 06800, Ankara, Turkey; d Department of Physics, Ahi Evran University, 40100, K?rsehir, Turkey; e Department of Physics, Nam?k Kemal University, 59030, Tekirda?, Turkey

Resume : In recent years, molybdenum oxide (MoOx) thin ?lms are of considerable interest in variety of technological applications as solar cell, gas and chemical sensors. Depending on the oxygen contribution, there are two main principal oxide phases in MoOx structure as to be molybdenum dioxide (MoO2) and molybdenum trioxide (MoO3). Additional phases can also be formed according to the Mo-O phase diagram, however they are expected to be in non-stoichiometric and more complex structural characteristics. In the case of MoO3, it has been reported in a transparent and insulating, layered material with an orthorhombic structure and the electrical resistivities of MoO3 is predicted to be in the interval of 1010 to 1011 ?.cm. Among the MoO3 integrated devices, a complete understanding of the material characterization of MoOx ?lms and its correlation to the tuning electronic and opto-electronic properties have been point of interest for improving their use in device applications. Therefore, in this work, transparent and conductive MoO3 thin film samples were deposited on the ultrasonically cleaned soda lime glass substrates by dc sputtering technique. The effect of sputtering power on their structural, electrical, and optical properties was systematically analyzed. The structure of the films was investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) detector facility. The optical properties of the ?lms are assessed through optical transition and band gap analyses. Moreover, the complementary characterization of the films was concentrated on temperature dependent conductivity for electrical analyses.

N.8.54
17:30
Authors : C.J.Gadiyar, M.Strach, R.Buonsanti
Affiliations : Department of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, Sion, Switzerland

Resume : With the age of fossil fuels moving towards its brink of exhaustion, the ever-rising global energy demand will be turning towards renewable resources. For the successful development of solar energy production, discovery and utilization of semiconductor materials with advantageous chemical and physical properties is crucial. Photoelectrochemical water splitting devices have been envisioned as a significant part of sustainable energy sources since the process was demonstrated for the first time1. Metal oxide semiconductors are seen as potential candidates for the role of photoanodes due to their stability during the application in oxidative environments. Binary metal oxides such as TiO2, ZnO, and WO3 suffer from high bandgap that lowers their photoconversion ability. Hence, the scientific community is focusing on developing complex metal oxides, which might exhibit lower band gaps and desirable band alignment for the water splitting reaction. One of the very recently suggested candidates for this application is the class of copper vanadates2. The seeded growth approach to produce complex metal oxide (Sb-BiVo4) thin films, starting from monodisperse metal seeds, has been successfully applied earlier in our group3 . In the current work, we synthesise monodisperse copper nanoparticles of 6, 15 and 40 nm using the colloidal synthesis approach. Vanadium acetylacetonate is used as a precursor for the second cation, which during the annealing process reacts with the nanoparticles to form copper vanadate. This approach has the advantage of growing the crystals at much lower temperatures (350℃, 2h) in comparison to the conventional methods (550 ℃, 10h)2. At such low temperatures the reaction becomes kinetically controlled, and allows one to overcome the thermodynamic limitations. Thus, by varying the time of annealing, quenching the oxygen supply for the reaction and controlling the seed size, it is possible to selectively grow Cu3VO4, Cu2V2O7 and Cu3V2O8 phases. From literature, it is known that Cu3VO4 is a p type semiconductor4, whereas Cu2V2O7 is a n type semiconductor5. We have shown that, when exposed to the same annealing process, 6 nm Cu seeds form Cu2V2O7 (n type) while, 40 nm Cu seeds form Cu3VO4 (p type). We hypothesise that this result is due to the different reactivity of copper for different seed sizes and further research is underway to support this claim. This result illustrates the unique ability to target the final crystalline phase of materials with complex phase diagrams by fine-tuning the seed size through colloidal synthesis, an approach not explored before. (1) Fujishima, A.; Honda, K. Nature 1972, 238 (5385), 37–38. (2) Zhou, L.; Yan, Q.; Shinde, A.; Guevarra, D.; Newhouse, P. F.; Becerra-Stasiewicz, N.; Chatman, S. M.; Haber, J. A.; Neaton, J. B.; Gregoire, J. M. Adv. Energy Mater. 2015, 5 (22), 1500968. (3) Loiudice, A.; Ma, J.; Drisdell, W. S.; Mattox, T. M.; Cooper, J. K.; Thao, T.; Giannini, C.; Yano, J.; Wang, L.-W.; Sharp, I. D.; Buonsanti, R. Adv. Mater. 2015, 27 (42), 6733–6740. (4) Sahoo, P. P.; Zoellner, B.; Maggard, P. A. J. Mater. Chem. A 2015, 3 (8), 4501–4509. (5) Guo, W.; Chemelewski, W. D.; Mabayoje, O.; Xiao, P.; Zhang, Y.; Mullins, C. B. J. Phys. Chem. C 2015, 119 (49), 27220–27227.

N.8.55
17:30
Authors : M.Vilaa,b, J. Rubio – Zuazoa,b, E. Salas - Coleraa,b, A. Pradosc,d and G. R. Castroa,b
Affiliations : aSpLine CRG BM25 Beamline, European Synchrotron Radiation Facility, 71, Avenue des Martys, 38000, Grenoble, France bInstituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (ICMM-CSIC) 28049, Madrid, Spain cDepartamento de Física de Materiales, Facultad de Ciencias Físicas, Universidad Complutense de Madrid,28040 Madrid, Spain dInstituto de Sistemas Optoelectrónicos y Microtecnología (ISOM), Universidad Politécnica de Madrid, 28040, Madrid, Spain

Resume : Chromia, α - Cr2O3, is a corundum-type crystal (crystalline form of α - Al2O3) with alternating oxygen layers and chromium bilayers along the c-axis of the hexagonal lattice. Bulk Cr2O3 present antiferromagnetic properties (TN = 307 K), exhibiting uniaxial magnetic anisotropy along [111]. These magnetic properties make Cr2O3 suitable for spintronic applications. However, complex oxides grown as thin film can result in a modification of their intrinsic properties, and therefore, it is crucial to fully understand structural, magnetic or electronic modifications of the thin films in comparison with the bulk. We have grown, for the first time, crystalline α-Cr2O3 thin films onto SrTiO3(111) substrates by PLD, as well as satisfactory, on Al2O3, due to their similar lattice parameters. The crystallographic properties of the grown films have been studied using synchrotron based GIXRD and XRR. A novel study of the coupling of the Cr2O3 lattice in both substrates has been fulfilled, revealing, for the Cr2O3/SrTiO3(111) thin films, an in-plane rotation of 30° of the layer respect to the underlying substrate. However, Cr2O3/Al2O3 are epitactical. These different orientations could result in divergent magnetic properties. Both samples present a sharp buried interface, with layers 16 nm thick. The film surfaces, investigated by AFM, show good homogeneity and low roughness. EXAFS and XANES measurements have been also performed to study the local coordination environment of Cr and O atoms.

N.8.56
17:30
Authors : I. Yildiz1,2,3, Hisham Nasser1, Gence Bektas1,4, R. Turan1,4,5, S. Yerci1,4,6
Affiliations : 1Center for Solar Energy Research and Applications (GÜNAM), Middle East Technical Univ., Ankara, Turkey 2Central Laboratory, Middle East Technical University, Ankara, Turkey 3Department of Physics, Dumlupinar University, Kutahya, Turkey 4Micro and Nanotechnology Programme, Middle East Technical University, Ankara, Turkey 5Department of Physics, Middle East Technical University, Ankara, Turkey 6Department of Electrical and Electronics Engineering, Middle East Technical University, Ankara, Turkey

Resume : Recently, dopant free silicon solar cells (Si SCs) based on metal oxide hole and electron transport heterocontacts have demonstrated itself as an alternative cost effective approach to the state-of-the-art high efficiency Si SCs. In contrast to the standard Si heterojunction design, rather than n- and p-type doped a-Si:H thin layers, carrier selective metal oxide materials with extreme work function (?) values are chosen to achieve carrier selectivity in dopant-free cell design. When a material with a very high ? is brought in contact to a lightly-doped Si, accumulation of holes (and repulsion of electrons) occurs near the surface. The corollary holds for electrons when a very low work function material is in touch with Si. In this manner, by placing materials with an extreme ? difference on either side of a Si, efficient separation of photogenerated carriers can be achieved. Therefore, ? and resulting band alignment of the carrier-selective materials play a crucial role in achieving high efficiency dopant free Si SCs. In this work, we measured ?, valance band maximum value (VBM) and band gap (Eg) of molybdenum oxide (MoOx), zinc oxide (ZnOx) and Si, and constructed the band alignment of MoOx/Si and ZnO/Si interfaces. While XPS was employed to measure the stoichiometry of materials, UPS measurements were carried to determine ? and VBM values. The band gap of the materials were calculated using Tauc plot constructed using the optical transmission and reflection spectra. A monochromatic Al K? line at 1486.6 eV and He-I line at 21.22 eV were used as light sources in XPS and UPS, respectively. MoOx (200 nm) and ZnOx (150 nm) films were deposited on cleaned Si wafers by thermal evaporation using MoO3 powders and by RF magnetron sputtering using a power of 300 W and an Ar flow rate of 20 sccm, respectively. XPS and UPS measurements were performed following a low energy (100 eV) Ar ion treatment for 5 min. To achieve high efficient dopant free Si SCs, on one hand, we need near-stoichiometric compositions to effectively passivate the defects on Si surface. On the other hand, sub-stoichiometric oxides allows higher conductivity required to transport charge carriers. In this study, stoichiometry values of ZnO0.96 and MoO2.56 were determined by XPS analysis. The measured band gap values (E_(g,?ZnO?_0.96 )=3.2 eV, E_(g,?MoO?_2.56 )=3.3 eV) are consistent with the measured stoichiometry values and the literature. Based on UPS analysis, we found that ?_(ZnO_0.96 ) and ?_(MoO_2.56 ) are equal to 3.99 eV and 4.92 eV, respectively. Additionally, we obtained the electron affinity values of both materials as ?_(?ZnO?_0.96 ) =3.77 eV and ?_(?MoO?_2.56 )=4.92 eV. It is obvious from the values that both ZnO0.96 and MoO2.56 are degenerately-doped n-type materials. Superior alignment of ZnO0.96 and Si conduction bands and that of MoO2.56 conduction band with Si valence band reveal that ZnO0.96 and MoO2.56 can be used in dopant free Si SCs. Further optimization of band alignment of electron and hole transport layers with Si will allow high efficient dopant free Si SCs.

N.8.57
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09:00 Plenary Session - Main Hall    
12:30 Lunch break    
 
Session 9: Oxides for Photocatalysis and Water Splitting : Catherine Marichy (France)
14:00
Authors : C. Maccato,1* D. Barreca,2 G. Carraro,1 A. Gasparotto1
Affiliations : 1 Department of Chemistry - Padova University and INSTM, 35131 Padova, Italy; 2 CNR-ICMATE and INSTM - Department of Chemistry - Padova University, 35131 Padova, Italy.

Resume : Solar energy technologies represent a unique opportunity to overcome issues related to the use of fossil fuels and the corresponding environmental pollution. In this regard, great efforts are being devoted to the study of sustainable energy alternatives with reduced ecological footprint. In particular, solar-driven hydrogen generation from water solutions by photo-activated processes has received a great attention as an amenable route to convert sunlight into storable chemical energy. In this scenario, the design of suitable supported photocatalysts with tailored structure, morphology and composition, is of key importance for H2 production. Fe2O3 represents an interesting option as photocatalyst thanks to its favourable chemico-physical properties. In particular, Fe2O3 nanosystems are very promising for the possibility of obtaining a minimized carrier-transport distance and a high surface area resulting in a recombination losses decrease. This contribution will provide a survey of our recent research activities on photo-activated H2 production promoted by supported Fe2O3-based nanosystems: i) anion-doped alpha-Fe2O3, the most thermodynamically stable polymorph; ii) beta- and epsilon-Fe2O3, two scarcely investigated phases, adopted for the first time in the target application; iii) Fe2O3/TiO2 nano-heterostructures, eventually functionalized with Au nanoparticles. The role of the interplay between synthesis parameters and the resulting systems functional properties will be also analyzed.

N.9.1
14:30
Authors : Ilia Valov
Affiliations : Peter Grünberg Institute (Electronic Materials), Research Centre Juelich, 52425, Juelich, Germany

Resume : Advances in science and technology have had a strong impact on the development of modern society. Among others, issues of high societal relevance are renewable ?green? energy conversion, energy storage, health/medicine, and information and communication technology, where ever-growing demands for improving efficiency, lowering power consumption, saving costs by avoiding precious/expensive materials, and making systems/devices smaller and smarter need to be met. New materials and devices are constantly being developed to meet these challenges. At the root of these material and device developments, across disciplines in physics, chemistry and engineering, are effects strongly related to and based on electrochemical fundamentals and processes. In the meantime, the advances in nanoscale materials and devices, along with new measurement and characterization techniques, have significantly advanced our understanding of electrochemical processes. Nanoscale materials with a broad variety of forms and properties have been developed ? nanoparticles, nm thick films or film stacks, nanotubes, embedded (nano)structured materials, etc. Some of them are reaching even atomic dimensions, in the case of 2D materials and atomic switches. At such scales the properties of matter can significantly deviate from those of their macroscopic descriptions. In addition to well-known size effects such as energy quantization, conductance quantization and Coulomb blockades, additional phenomena arise from the different thermodynamic and kinetic factors of nanosized systems. For example, for nanoscale systems space-charge regions can become larger than the electrolyte thickness, inducing fully depleted or fully enriched regions. Additionally, lattice misfit and specific surface termination occurring at interfaces can induce 2D electron gas phenomena. These material and technology advances in turn pose opportunities and challenges for the understanding and control of the physical and physicochemical processes of matter at the atomic and mesoscopic levels. In this contribution, the fundamentals of nanoscale electrochemistry with insulators will be discussed. Experimental results and discussion on interface interactions, charge transfer processes and ion transport in nano-scaled electrochemical systems using SiO2 and Ta2O5 as ion transporting solid (solid electrolyte) will be shown. The structure and reactivity of the interfaces appear to be of crucial importance for reproducible and reliable experiments. We demonstrate that both potentiodynamic and steady state measurements can be used to determine reaction kinetics parameters. The influence of the counter charge/electrode reaction and its influence on the overall cell behavior will be emphasized as well as the role of the electrocatalytic activity of the electrodes. The dynamics of electrochemical processes in/within insulators will be shown and the activity and mobility of different cations such as Ag, Cu, Ta, Ti etc. as well as noble metals e.g. Pt and Pd will be demonstrated. Our results highlight electrochemical systems in a qualitatively different way, showing deviations in thermodynamics and kinetics at the nanoscale.

N.9.2
15:00
Authors : Francesca Riboni,1,2 Seulgi So,1 Ning Liu,1 Patrik Schmuki1,2
Affiliations : 1Department of Materials Science and Engineering WW4-LKO, University of Erlangen-Nuremberg, Martensstrasse 7, Erlangen, D-91058, Germany 2Regional Centre of Advanced Technologies and Materials, Faculty of Science, Palacky University, 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic

Resume : One-dimensional TiO2 nanotubes (NTs) by electrochemical anodization are currently used in a wide range of energy-related and bio-applications. 1D TiO2 NTs are typically grown on a Ti foil and, if separated from the metallic substrate, can form both-side-open NT membranes that provide an ideal geometric arrangement for e.g. flow-through applications. However, NT membranes usually suffer from poor mechanical stability and, when annealed, feature voids or other morphological defects that have so far hindered any potential development of functional NT membrane devices. We report the fabrication of robust, free-standing and crystalline TiO2 NT membranes, achieved by producing nanotube layers in the presence of lactic acid electrolyte, followed by chemical etching for tube detachment from the Ti substrate. This type of NT membrane features no morphological damage over their entire surface area and thickness, and withstands annealing treatment up to ~ 1000°C without curling or cracking and, most remarkably, maintaining a full anatase phase composition. We demonstrate that the high crystallinity and pure anatase phase composition of these layers, combined with their robustness, are keys for their use in a flow-through photoreactor for the degradation of Acid Orange 7 (AO7). By combining the permeability characteristics of a defect-free tube membrane with the desired photocatalytic activity of crystalline TiO2, we could achieve and control AO7 diffusion through the tubes along with its photocatalytic degradation.

N.9.3
15:15
Authors : Ning Liu, Francesca Riboni, and Patrik Schmuki
Affiliations : Department of Materials Science WW-4, LKO, University of Erlangen-Nuremberg, Martensstrasse 7, 91058 Erlangen, Germany

Resume : ‘Black’ TiO2 – in the widest sense TiO2 reduced by various treatments – has gained in recent years tremendous scientific interest because of some outstanding properties; including a strong visible light absorption (the blacker, the better). We show that high pressure hydrogenated TiO2 in the form of nanotubes and powder shows another key feature, that is, a strongly enhanced photocatalytic activity for hydrogen production in absence of any noble metal cocatalyst. The work shows that the proper high pressure hydrogenation on TiO2 can provide a cocatalytic center, similar in its effect to noble metal decoration. This catalytic center is proposed to involve an unusually stable Ti3+ species with characteristic EPR and PL features. The intrinsic activity for photocatalytic hydrogen evolution is not coupled with the visible light absorption behavior, but it rather must be ascribed to an optimized and specific defect-center. It is found that a highest photocatalytic activity from an optimized hydrogen treatment that leads to ‘grey’ anatase; we discuss structure, morphology, composition, and defect structure of this noble metal free modification of a H2 evolution TiO2-photocatalyst.

N.9.4
15:30 Coffee break    
 
Session 10: Superlattices and Heterostructures : Stefan Foerster (Germany)
16:00
Authors : Daniel Pingstone, Balati Kuerbanjiang, Kelvin H L Zhang, Vlado K Lazarov
Affiliations : Department of Physics, University of York, Heslington, York, YO10 5DD, UK; Department of Physics, University of York, Heslington, York, YO10 5DD, UK; Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK; Department of Physics, University of York, Heslington, York, YO10 5DD, UK

Resume : Thin films of MgO are of interest for both spin-electronics and CMOS type of devices, due to its spin-filtering property, high dielectric constant and large band gap. This work demonstrates feasibility of single crystal growth of polar MgO(111) at low temperatures on 6h-SiC, despite a lattice mismatch of 3 %. The films have been analysed using in situ electron diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and electrical measurements. From these experimental techniques, we have observed epitaxial growth of MgO on Si- and C- terminated 6h-SiC surfaces and determined the valence and conduction band offsets for the MgO/6H-SiC hetero-interface. In addition we demonstrate the film surface morphology control between faceted (100) and atomically flat (111) type of surfaces as a function of oxygen plasma pressure and film deposition rate.

N.10.1
16:15
Authors : A. Kozanecki*, J. Sajkowski, M. Pietrzyk, M. Stachowicz, P. Dluzewski
Affiliations : Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46 PL-02-668 Warsaw, Poland

Resume : Solid solutions of ZnO with MgO for Mg content above 45% have a tendency to segregate to hexagonal and cubic crystal phases. In ZnO/MgO superlattices (SL) it is possible to manipulate with layer thicknesses to avoid metastability and to get the whole superlattice in the wurtzite structure while preserving the wide band gap of alloy. Short period ZnO/MgO SLs with pair thicknesses on the order of few lattice constants can also be treated as ordered alloys. In this work we attempt to realize ZnO/MgO superlattices with the thickness of ZnO and MgO layers on the order of 0.5-2 nm. The number of ZnO/MgO pairs was 50-80. SLs were deposited on c- and a-oriented bulk ZnO substrates. The existence of local SLs and their thicknesses have been confirmed by Transmission Electron Microscope imaging. Two dominant emission bands were observed in photoluminescence (PL) of all the SLs which behaved differently with temperature. In the PL spectra of SLs deposited on c-ZnO we observed a PL band typical for random ZnMgO alloys and also a lower energy band revealing anomalously large red-shift of 160 meV between 10K and 180K. In the case of SLs grown on m-ZnO polarization studies of the PL were also performed. It was found that the degree of polarization of these two PL bands differs. We interpret the PL spectra of the SLs in terms of recombination of excitons in ordered and disordered regions of ZnO/MgO structures. The research was supported by the NCN project DEC-2014/15/B/ST3/04105.

N.10.2
16:30
Authors : J. Tamayo-Arriola, M. Montes Bajo, D. Lefebvre, N. Le Biavan, M. Hugues, J.M. Ulloa, J.M. Chauveau, A. Hierro
Affiliations : J. Tamayo-Arriola; M. Montes Bajo; J.M. Ulloa; A. Hierro: ISOM and Dept. Ingeniería Electrónica, Universidad Politécnica de Madrid, Spain D. Lefebvre; N. Le Biavan; M. Hugues; J.M. Chauveau: Université Côte d'Azur, CNRS, CRHEA, Valbonne, France

Resume : The field of electronic unipolar devices, including THz QCLs and HEMTs, remains wide open for ZnO/MgxZn1-xO heterostructures. However, they require a high control of the heterointerfaces as well as an accurate knowledge of their electrical and transport characteristics. Depending on the application, large Mg contents as well as high n-type dopings have to be achieved, which will directly impact some of the key material parameters, such as effective mass (meff), carrier concentration or mobility. We combine IR reflectance spectroscopy, UV absorption spectroscopy, Hall Effect, and Capacitance-Voltage profiling, to fully characterize a series of non-polar m-plane MgxZn1-xO layers grown by MBE on m-sapphire with varying Mg concentrations (0 % to 50 %) and Ga dopings (undoped to above 10E19 cm-3). We obtain the plasma frequency from fitting the reflectance spectra with a dielectric function model built with a Drude term for free electrons and Gervais oscillators for the phonon modes. The plasma frequency, along with the electron density and mobility extracted from Hall effect, are used to deduce meff. The incorporation of Mg in the structure is assessed by measuring the optical absorption band edge of the structures. Thus, we establish a correlation between Mg/Ga incorporation, meff and measured electron density and mobility for the same doping level. This project has received funding from EU Horizon 2020 research and innovation programme under grant No 665107 (project ZOTERAC).

N.10.3
16:45
Authors : Johanna K. Jochum 1, Michael Lorenz 2, Haraldur P. Gunnlaugsson 3, Christian Patzig 4, Thomas Höche 4, Marius Grundmann 2, André Vantomme 3, Kristiaan Temst 3, Margriet J. Van Bael 1 and Vera Lazenka 3
Affiliations : 1: KU Leuven, Laboratorium voor Vaste-Stoffysica en Magnetisme, Celestijnenlaan 200D, 3001 Leuven, Belgium ; 2: Felix-Bloch-Institut für Festkörperphysik, Universität Leipzig, Linnéstraße 5, D-04103 Leipzig, Germany; 3: KU Leuven, Instituut voor Kern en Stralingsfysica, Celestijnenlaan 200D, 3001 Leuven, Belgium ; 4: Fraunhofer-Institut für Mikrostruktur von Werkstoffen und Systemen (IMWS), Center for Applied Microstructure Diagnostics, D-06120 Halle, Germany;

Resume : Multiferroic magnetoelectric heterostructures are an intriguing candidate for the next generation data storage devices, where their unique properties can be utilized to control a single magnetic bit using electric fields. The understanding of the coupling between the magnetic and electric properties in these materials is paramount. We report here on one of the highest values of the magnetoelectric voltage coefficient published so far. It reaches its maximum of 60.2 V / (cm Oe) at 300 K, for a BaTiO3 ? BiFeO3 superlattice with a BaTiO3 thickness of 10 nm and a BiFeO3 thickness of 5 nm. We have studied the origin of the increased magnetoelectric coupling in BaTiO3 ? BiFeO3 superlattices, using SQUID magnetometry, conversion electron Mößbauer spectroscopy and magnetoelectric voltage measurements and found that the magnetoelectric coupling can be tuned by varying the BiFeO3 layer thickness. The temperature dependencies of the magnetoelectric voltage coefficient lead us to the conclusion that the main mechanism responsible for the magnetoelectric coupling at 300 K is dominated by charge transfer for the sample with a BiFeO3 layer thickness of 50 nm. With decreasing BiFeO3 thickness the main coupling mechanism is dominated more and more by strain. Furthermore we established a correlation between the hyperfine field, magnetoelectric voltage coefficient and the magnetization.

N.10.4
17:00
Authors : F. Bouhjar , B.Marí and B. Bessaïs
Affiliations : a. Institut de Disseny i Fabricació, Universitat Politècnica de València. Camí de Vera s/n 46022 València (Spain) b. Laboratoire Photovoltaïques, Centre de Recherches et des Technologies de l?Energie Technopole H.lif 2050(Tunisia) c. University of Tunis

Resume : p-CuSCN/n-Fe2O3 heterojunctions were electrochemically prepared by sequentially depositing ?-Fe2O3 and CuSCN films on FTO substrates. ?-Fe2O3 and CuSCN films and ?-Fe2O3/CuSCN heterojunctions were characterized by Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray spectroscopy (EDX), and X-Ray Diffraction (XRD) measurements. Pure crystalline CuSCN films were electrochemically deposited on ?-Fe2O3 films by fixing the SCN/Cu molar ratio in the electrolytic bath to 1:1.5 at 60 °C and a potential of -0.4 V. The photocurrent measurements showed an increase of the intrinsic surface states or defects at the ?-Fe2O3/CuSCN interface. The photoelectrochemical performance of the ?-Fe2O3/CuSCN heterojunction was examined by chronoamperometry and linear sweep voltammetry techniques. It was found that the ?-Fe2O3/CuSCN structure exhibits a higher photoelectrochemical activity when compared to ?-Fe2O3 thin films. The highest photocurrent density was obtained for ?-Fe2O3/CuSCN films in 1 M NaOH electrolyte. This high photoactivity was attributed to the high active surface area and to the external applied bias favoring the transfer and separation of photogenerated charge carriers in ?-Fe2O3/CuSCN heterojunction devices. The flat band potential and the donor density were found to be maximal for heterojunction sample. These results suggest a substantial potential for applying heterojunction thin films in photoelectrochemical water splitting applications.

N.10.5
17:15
Authors : Iciar Arnay (a,b), Juan Rubio-Zuazo (a,b), Min-Hsiang Mark Hsu (c,d), Ziyang Liu (c,e), Clement Merckling (c), German R. Castro (a,b)
Affiliations : (a) BM25-SpLine, ESRF (European Synchrotron Radiation Facility), 71 Avenue Martyrs, 38000 Grenoble, France (b) ICMM-CSIC (Instituto de Ciencia de Materiales de Madrid), Ciudad Universitaria de Cantoblanco, 28049 Madrid, Spain (c) imec, Kapeldreef 75, 3001 Leuven, Belgium (d) Photonics Research Group, INTEC, Ghent University?imec, 9000 Gent, Belgium (e) Department of Metallurgy and Materials Engineering, KULeuven, 3001, Leuven, Belgium

Resume : Spintronic offers a new range of possibilities for new semiconductor-based data processing and memory applications. The successful application of this technology relies on the efficiency injection of spin-polarized electrons into a semiconductor host material, which is directly related with the quality of the engineered heterostructures. The presence of non-stoichiometry phases and the formation of structural defects, especially at the interfaces can be detrimental for the functional properties of the system. Within this context, we have successfully prepared epitaxial Fe3O4/SrTiO3/Si heterostructures. SrTiO3 ultrathin films were evaporated on Si (001) by MBE while Fe3O4 films were subsequently deposited by PLD. Both layers shows fully relaxed character. The SrTiO3 films grow with its axis rotated 45 degrees respect to those of the Si meanwhile Fe3O4 films grow with a (100) orientation on SrTiO3 axis. A complete structural and electronic characterization of the SrTiO3 tunnel barrier and Fe3O4 electrode was performed by Reflected High-Energy Electron Diffraction (RHEED), X-Ray photoelectron spectroscopy (XPS) and Synchrotron Radiation X-Ray Diffraction and Reflectivity (SR-XRD/XRR). A discussion of the tunnel barrier stability versus Fe3O4 film quality as a function of the evaporation conditions will be presented.

N.10.7
18:00 Best Student Presentation Award & Reception 18:00-21:00 (Main Hall)    
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Session 11: Functional Oxide Growth and Synthesis : David Grosso (France)
08:45
Authors : S.G. Nedilko
Affiliations : Taras Shevchenko National University of Kyiv, 64/13 Volodymyrska st., 01601 Kyiv, Ukraine

Resume : The work presents both review and original data about modern state of art concerning structure, physical properties, applications and prospects of some polymer based composites incorporated with micro/nanosized particles of various oxide compounds. The results of synthesis, structure, morphology and spectroscopic study of the luminescent oxides like to doped with RE ions simple MI/MII oxides and complex oxide containing various metal cations (MI ? MIV; Na, Ca, Bi, Zr, e.g.) and molecular anions (B = phosphate, molybdate, tungstate, etc) were described. These materials can be useful in creation of new optoelectronics devices (WLED, phosphor converting layeres for solar elements covering, biomarkers, etc). Great attention was paid to the study of composite materials where micro/nanocellulse is a matrix or alternatively component of the composites. Cellulose comprising composites have strong promise due to their light weight, high tensile strength and modulus, and comparably low cost. Microcrystalline cellulose is pure partially depolymerized cellulose synthesized from ?-cellulose precursor Three sets of the samples, that are ?MNC-oxides?, ?polyethylene-oxides? and ?polyethylene-MNC? micro/nanocomposites were prepared and studied. There mechanical and thermal properties, (humidity and humidity sorption capacity, porosity, density, compressibility index, particles size, crystallinity index) were measured as they are important to qualify the suitability of such materials as valuable additives in pharmaceutical, food, cosmetic, etc. Dielectric and optical characteristics, and luminescence is among them, were studied as well as they show perceptiveness of such materials to be used in hi-tech devices. Obtained results were analyzed and discussed.

N.11.1
09:00
Authors : Vijay Kumar
Affiliations : Department of Applied Physics, Chandigarh University, Gharuan, Mohali (Punjab), India

Resume : The scientific community accepted 2015 as the International Year of Light and Light-based Technologies due to the thrust of luminescent materials in every part of the human expansion. The light-based technologies have transformed into various sectors of science and technology to a larger size. Notable research activities have been targeted to find cost-effective, environment-friendly, better performance, and energy-efficient phosphor materials for the application in the solid-state lighting devices. The urge of luminescent materials with better optical and photoluminescence characteristics in a large number of areas has shared the research endeavors in this field intended to improve the material properties. In the past decades, much research interest has been focused on phosphors based on various inorganic and organic materials owing to their extensive applications in light-emitting diodes, cathode ray tubes, scintillation detectors and biological technologies. The phosphors based on various inorganic and organic materials are highly conductive to release electric charges stored on the surface and as a result, they have emerged as potential candidates for use in field emission display and plasma display panel devices. It is well known that rare earth (RE) ions doped phosphor materials have been treated as efficient candidates for generating various emission wavelengths which have many applications in solid state lighting, display devices etc. The emission of RE-doped phosphor at the particular wavelength range is because of the superb luminescence characteristics of the RE ions. This talk will cover the broad aspects of RE-doped oxide materials for tunable color emissions. Much of the material is drawn from the personal experience in synthesizing, characterizing and applying them for solid state lighting.

N.11.2
09:15
Authors : E.D. Politova, D.A. Belkova, D.A. Strebkov, N.V. Golubko, A.V. Mosunov, N.V. Sadovskaya, G.M. Kaleva, S. Yu. Stefanovich, P.K. Panda
Affiliations : L.Ya.Karpov Institute of Physical Chemistry; Vorontsovo pole, 10, Moscow, Russia, 105064 Lomonosov Moscow State University; Leninskie gory, 1, Moscow, Russia, 119992 National Aerospace Laboratories, Kodihalli, Bangalore-560017 India

Resume : Processing and characterization of lead-free ceramics on the base of sodium-bismuth titanate and sodium-potassium niobate E.D. Politova1, D.A. Belkova2, D.A. Strebkov2, N.V. Golubko1, A.V. Mosunov1, N.V. Sadovskaya1, G.M. Kaleva1, S. Yu. Stefanovich1,2, P.K. Panda3 1L.Ya.Karpov Institute of Physical Chemistry; Vorontsovo pole, 10, Moscow, Russia, 105064 2Lomonosov Moscow State University; Leninskie gory, 1, Moscow, Russia, 119992 3National Aerospace Laboratories, Kodihalli, Bangalore-560017 India E-mail: politova@cc.nifhi.ac.ru Lead-free piezoelectric materials are among the most intensively studied in order to replace widely used Pb-based ones. In this work, effects of modification of compositions by various donor and acceptor dopants in the A- and B-sites of perovskite lattice and influence of nonstoichiometry on structure, dielectric and ferroelectric properties of ceramics from Morphotropic Phase Boundaries (MPB) in the (K0.5Na0.5)NbO3 (KNN), (Na0.5Bi0.5)TiO3 (NBT) and (Na1/2Bi1/2)TiO3 - BaTiO3 (NBT-BT) systems have been studied. Ceramic samples were prepared by the two-step solid-state reaction method at high temperatures of 970 ? 1470 K. The samples were characterized using the X-ray Diffraction, Differential Thermal Analysis, Scanning Electron Microscopy, Second Harmonic Generation (SHG), and Dielectric Spectroscopy methods. Depending on the cation ionic radii changes in the unit cell volume of the KNN- and NBT-based ceramics were observed. Ferroelectric phase transitions marked by steps at ~ 350 - 400 K (NBT) and by peaks at ~ 550 K (NBT) and at ~700 K (KNN) were revealed in the dielectric permittivity versus temperature curves of the compositions studied. Ferroelectric phase transitions near 350-400 K revealed typical relaxor-type behavior attributed to the presence of polar nanoregions in a nonpolar matrix. Increase in the spontaneous polarization value was proved for modified ceramics using the SHG method. At the room temperature, non monotonous changes of the dielectric parameters ?rt and tan?rt were observed in modified BNT- and KNN-based compositions, thus confirming prospects of new lead-free materials development. Acknowledgment. The work was supported by the Russian Foundation for Basic Research (Project 16-16-53-48009).

N.11.3
09:30
Authors : Markku Leskelä, Timo Hatanpää, Mikko Heikkilä, Jani Hämäläinen, Tomi Iivonen, Kaupo Kukli, Katja Väyrynen, Mikko Ritala
Affiliations : Department of Chemistry, PO Box 55, University of Helsinki, FI-00014 Helsinki, Finland

Resume : Transition-metal oxides exhibit a wide range of technically important electronic properties which include magnetic, dielectric, ferroelectric, catalytic, superconductive, redox, thermoelectric, and multiferroic properties, insulator?metal transitions, and mixed electronic/oxide ion conduction. [1] The list of properties is valid also for late transition metals of the 1st row (Fe, Co, Ni, Cu) and these interesting properties can be utilized in many micro- and nanodevices. The catalytic properties of the metal oxides have recently been widely studied in visible light photo- or electrocatalysis to destroy organic pollutants or water splitting. Common feature of transition metals is their ability to exist on different oxidation states and the properties of the oxides may accordingly vary significantly. The electronic properties (band gap) of transition metal oxides can be controlled by the size and dimension making the nanostructures very interesting. [2] In many of the applications the oxides are employed as thin films or nanoparticles. Often also ultrathin or conformal films are looked for and then ALD deposition technology is desired. ALD processes for iron, cobalt, nickel and iron are presented. Volatile metal compounds are typically cyclopentadienyls, ?-diketonates, carboxlates or aminoalkoxides. Oxygen precursor is very important in controlling the stoichiometry. Typically ozone is producing the higher oxidation state oxide while in water processes the low oxidation state or mixed oxidation state oxides are formed. Temperature is another important parameter in oxidation state control and at higher temperatures the oxygen metal ratio tends to decrease. In the presentation besides the ALD processes selected properties of the transition metal oxides will be discussed. Special attention will be given for the photocatalytic properties. [1] J.B. Goodenough, Chem. Mater 26 (2014) 820. [2] T. Guo, M.-S. Yao, Y.-H. Lin, C.-W. Nan, CrystEngComm 17 (2015) 3551.

N.11.4
10:00
Authors : Yu-Feng Yao, Huang-Hui Lin, Shaobo Yang, Keng-Ping Chou, Hao-Tsung Chen, Chia-Ying Su, Charng-Gan Tu, Chun-Han Lin, C. C. Yang
Affiliations : National Taiwan University, Taipei, Taiwan

Resume : Highly Ga-doped ZnO (GaZnO) nanoneedles (NNs) are formed based on the vapor-liquid-solid (VLS) growth mode by using Ag nanoparticles (NPs) as growth catalyst. During the growth of such NNs, a GaZnO thin film is simultaneously deposited through the vapor-solid (VS) growth mode, i.e., without using a catalyst. The polarities of such GaZnO thin films and NNs are analyzed with the annular bright field imaging technique in aberration corrected STEM observation. It is found that the polarity of a GaZnO thin film depends on that of the growth template. More specifically, the growth of a GaZnO thin film on Ga-face GaN or Si-face SiC (N-face GaN or C-face SiC) leads to a Zn-polar (O-polar) structure. However, the polarities of all the GaZnO NNs grown on Ga-face GaN, N-face GaN, Si-face SiC, and C-face SiC templates are Zn-polar. In other words, the VLS growth always results in Zn-polar GaZnO and the VS growth leads to the GaZnO polarity the same as that of the template. These different polarity results are caused by the different channels of metal and oxygen incorporations in the VLS process. From our EDX analysis, we can observe residual Ga and Zn atoms in the top Ag NP of a GaZnO NN, confirming that the metal atoms are adsorbed by the catalytic Ag NP during the VLS process. However, the oxygen atoms can incorporate from the VLS three-phase junction into the liquid-solid interface. Therefore, the first atomic layer in the precipitated GaZnO is oxygen, leading to Zn-polar polarity.

N.11.5
10:15
Authors : T. Pauporté, O. Lupan, L. Chow and R. Adelung
Affiliations : Institut de Recherche de Chimie-Paris, UMR8247, ENSCP-PSL Research University, 11rue P. et M. Curie, 75231 paris cedex 05, France. Department of Microelectronics and Biomedical Engineering, Technical University of Moldova, Chisinau, Moldova. Department of Physics, University of Ccentral Florida, Orlando, 32816 USA. Institute for Materials Science, University of Kiel, Christian-Albrechts Universität zu Kiel, Germany.

Resume : ZnO, a wide bandgap II-VI semiconductor (Eg = 3.4 eV) with a large exciton binding energy (60 meV), is widely studied for optical and electronic applications. ZnO can be grown from solutions by several techniques such as hydrothermal deposition, chemical bath deposition and electrochemical deposition (ECD). Electrochemical deposition is of utmost interest for integration of the films in optoelectronic devices since they are low-temperature and low-cost methods which can be scaled-up for film preparation on large surface area substrates. Moreover, due to the electron exchange process at the origin of the oxide deposition, a good electrical continuity is insured between the substrate and the oxide layer.[1] We will describe the technique of electrochemical deposition of ZnO nanowires with a high structural quality. The growth of nanocolumn and nanowire arrays can be achieved by the method with controlled aspect ratio, density and optical properties.[2-4] The final structure can be finely tuned by adjusting the precursor concentration in the bath, the deposition time, the substrate and so on. We have also shown that doping with various transition metals such as Cu, Cd, Ag, Pd with a controlled concentration can be easily achieved by the technique.[5] These nanowires have been used as single functional nanosensors with significantly changed detection properties and improved selectivity with different dopant concentrations. All these aspects will be described in detail in the talk. References 1. H. Elbelghiti, Pauporté, D. Lincot, Phys. Stat. Sol. (a) 205, 2360 (2008). 2. T. Pauporté, D. Lincot, B. Viana, F. Pellé , Appl. Phys. Lett., 89, 233112 (2006). 3. O. Lupan, T. Pauporté, T. Le Bahers, B. Viana, I. Ciofini, Adv. Funct. Mater., 21 3564 (2011). 4. O. Lupan, L. Chow, T. Pauporté, L.K. Ono, B. Roldan Cuenya, G. Chai, Sensors and Actuators B, 173 772 (2012). 5. O. Lupan, V. Cretu, V. Postica, M. Ahmadi, B. Roldan Cuenya,L. Chow, I. Tiginyanu, B. Viana, Th. Pauporté, R. Adelung, Sensors Actuators B, 223, 893 (2016).

N.11.6
10:30 Coffee break    
 
Session 12: Oxide Synthesis II : Adrian Kozanecki (Poland)
11:00
Authors : D. Grosso
Affiliations : Institut Matériaux Microélectronique et Nanosciences de Provence, (IM2NP) - UMR CNRS 7334, NOVA Team, Aix-Marseille Université, Faculté des Sciences de Saint Jérôme, 13397 Marseille Cedex 20, France. Email: David.grosso@im2np.fr / +33 6 80762558}

Resume : Complex hierarchical nano structures can be achieved when combining chemical advanced bottom-up strategies, such as self-assembly and sol-gel chemistry, together with high throughput liquid solution processing. Amongst them, dip-coating is an extremely versatile tool to prepare thin nanostructured (hybrid), mesoporous metal oxide films from liquid solutions and has been used for many decades without taking advantage of its whole potentiality. [1,2] This communication reports on the recent progresses performed in nanostructing sol-gel coatings through a perfect control of the chemical and processing conditions, and the exiting possibilities associated to its combination with conventional “top-down” micro(nano) fabrication technologies such as Soft-NIL, RIE, optical lithography or FIB, to construct even more complex morphologies with multi scales features and motifs. [3] Interests of such complex patterned coatings will be illustrated with recent implementations for application in various domains such as for nano actuation, [4] photonics [5], gas sensing, [6] nanofluidic, [7] and surface wetting. [8] [1] D. Ceratti et al. A New Dip Coating Method to Obtain Large‐Surface Coatings with a Minimum of Solution. Adv. Mater. 2015, 27, 4958-4962. [2] Faustini M., et al. Engineering Functionality Gradients by Dip Coating Process in Acceleration Mode, ACS Appl. Mater. & Interf. 2014, 6, 17102–17110. [3] M. Faustini, et al. Self-assembled inorganic nanopatterns (INPs) made by sol-gel dip-coating: Applications in nanotechnology and nanofabrication. (Invitation) CRASS, 2016, 19, 248-265. [4] M. Boudot, et al. Converting Water Adsorption and Capillary Condensation in Useable Forces with Simple Porous Inorganic Thin Films. ACS Nano 2016, 10 (11), 10031–10040. [5] T. Bottein, et al. "Black" Titania coatings composed of sol-gel Imprinted Mie resonators arrays. Adv. Funct. Mater. 2016 (DOI: 10.1002/adfm.201604924). [6] M. Boudot, et al. Ethanol–water co-condensation into hydrophobic mesoporous thin films: example of a photonic ethanol vapor sensor in humid environment. J. Sol-Gel Sc. Technol. 2016 DOI 10.1007/s10971-016-4084-2. [7] D. R. Ceratti, et al. Ionic diffusion, nanoparticle formation and trapping within sol-gel made Pillar Planar Nanochannels in a simple microfluidic devices. Submitted. [8] M. Faustini, et al. Dynamic Shaping and Manipulation of Femtoliter Dew Droplets on Nanoimprinted TiO2 Hydrophilic Surfaces. Submitted.

N.12.1
11:30
Authors : Andrzej Calka
Affiliations : School of Mechanical, Materials, Mechatronic and Bioengineering, University of Wollongong, NSW 2522, Australia

Resume : The conventional method to prepare functional oxides is ceramic-powder-based processing, i.e., through solid-state reaction at high temperatures. This process has several disadvantages, such as high-temperature reaction, limited degree of chemical homogeneity, and low sintering ability. Therefore, during past years, several chemical-based processing routes, including freeze-drying, spray-pyrolysis, sol? gel, spray-drying, and pyrolysis of complex compounds, have been developed to prepare powders with more homogeneous composition, improved reactivity, and sintering ability at low temperatures. Recently, non-conventional processing methods such as mechanical alloying and mechano-chemical approaches have been used to create reactions between species. However in this method the reaction kinetics is very slow and processing time long. Here we report application of an Electric Discharge Assisted Mechanical Milling (EDAMM)[1] technique to synthesize various functional oxides. By using EDAMM, high purity single phase multi-element oxides can be formed in as little as 0.1% of the processing time required in conventional solid-state techniques. An even more important feature of EDAMM is that the crystallite size of the synthesized compound is able to be reduced to nanometer size , by careful selection of electrical (voltage, current, total power) and mechanical (vibration frequency and amplitude) experimental parameters. We use EDAMM for (i) synthesis of oxides from elemental powders by oxidation in oxygen plasma and for (ii) synthesis of single phase multi element oxides from pre-mixed oxides as starting materials. In the former case we investigated the effect of oxygen, argon, helium, nitrogen, AC and DC plasmas on phase formation, rate of synthesis and powder morphology. This presentation provides an overview of recent development of Electric Discharge Assisted Mechanical Milling and its application in rapid complex oxides processing and synthesis. In particular: i) detailed analysis of the method will be presented, ii) the effect of AC and DC discharges on phase transformations in solid will be discussed, iii) characteristic of power supplies, construction of reaction chambers unusual effects of electrode coatings will be presented and discussed. Example applications of this method: The following compounds: MgAl2O4, LiFePO4, CaCu3Ti4O12, BaLa2Ti4O12, Nd2Ba2CaZn2Ti3O14 and many others were synthesized within minutes. We found that using EDAMM method, non-stoichiometric oxides, can be synthesized with compositions not achievable by conventional methods. Samples were characterized using x-ray analysis, SEM, TEM and capacitance measurement. The EDAMM technique offers an exciting opportunity to synthesize a range of new and existing materials to be used in a variety of energy storage applications that include rechargeable lithium batteries, hydrogen fuel cells, and super-capacitors. [1] A.Calka and D.Wexler, Nature, 419,(2002)147-151

N.12.2
12:00
Authors : Konstantinos Chatzipanagis, Tomasz Stawski, Liane G. Benning
Affiliations : Konstantinos Chatzipanagis (German Research Centre for Geosciences, GFZ, 14473 Potsdam, Germany); Tomasz Stawski (German Research Centre for Geosciences, GFZ, 14473 Potsdam, Germany); Liane G. Benning (German Research Centre for Geosciences, GFZ, 14473 Potsdam, Germany), (Department of Earth Sciences, Free University of Berlin, 12249 Berlin Germany), (School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK)

Resume : Gypsum is one of three main phases of calcium sulfate [1] and is the most abundant evaporitic mineral on the Earth?s and Mars? surfaces. In industry, the main constituent in plaster products for casting and construction applications, it is widely used as a fertilizer and as an additive in concrete. On the other hand, the unwanted precipitation of gypsum constitutes one of the main hurdles in making sea water desalination plants. Hence, comprehending the fundamental mechanisms driving the formation of gypsum from dissolved ions is of paramount importance. Here we present data from the development and testing of a custom-made cell flow reactor coupled to a Raman microscope stage that allowed us to follow the time-dependent changes in the Raman spectra during the formation of gypsum from mixed aqueous solutions of sodium sulfate and calcium chloride [1]. The Raman spectra show a concurrent decrease of the Raman band intensity of the S-O stretching mode of the aqueous sulfate at 980 cm?¹ and an increase of the corresponding band of crystalline gypsum at 1007 cm?¹. We found that the band intensities were linearly proportional to the actual concentrations of the corresponding phases. Based on this, the apparent rate of disappearance of the aqueous sulfate was faster than the appearance of gypsum, which could indicate the formation of a new precursor phase preceding the crystalline gypsum. These results nicely complement our previous in situ gypsum formation studies using scattering [1], but importantly demonstrate the feasibility of a new cell system to perform real in situ Raman studies of phase formation in liquid environments. [1]. M. Stawski, A. E. S. van Driessche, M. Ossorio, J. D. Rodriguez-Blanco, R. Besselink and L. G. Benning, Nat. Commun., 2016, 7, 11177, DOI: 10.1038/ncomms11177.

N.12.3
12:15
Authors : Olga A. Krysiak1,2, Grzegorz Cichowicz3, Wojciech Hyk3, Michal Cyranski3, Jan Augustynski1
Affiliations : 1 Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland 2 College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland 3 Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland

Resume : Metal oxides are known electrocatalyst in water oxidation reaction. Due to the fact that it is desirable for efficient oxygen evolution catalyst to contain numerous redox-active metal ions to guard four electron water oxidation reaction, mixed metal oxides exhibit enhanced catalytic activity towards oxygen evolution reaction compared to single metal oxide systems. On the surface of fluorine doped tin oxide coated glass slide (FTO) deposited (doctor blade technique) mixed metal oxide layer composed of nickel, iron and chromium. Oxide coating was acquired by heat treatment of the aqueous precursors solutions of the corresponding salts. As-prepared electrodes were photosensitive and acted as an efficient oxygen evolution catalyst. Our results showed that obtained by this method electrodes can be activated which leads to achieving of higher current densities. The recorded current and photocurrent associated with oxygen evolution process were at least two orders of magnitude higher in the presence of oxide layer compared to bare FTO electrode. The overpotential of the process is low (ca. 0,2 V). We have also checked the activity of the catalyst at different known photoanodes used in sun-driven water splitting. Herein, we demonstrate that we were able to achieve efficient oxygen evolution catalysts using relatively cheap precursor consisting of earth abundant metals and simple method of preparation.

N.12.4
12:30 Lunch break    
 
Session 13: Defects : Chih-Chung Yang (Taiwan)
13:45
Authors : Naoki Ohashi(1,2), Takeo Ohsawa(1), Isao Sakaguchi(1)
Affiliations : (1) National Institute for Materials Science, Japan; (2) Materials Center for Elemental Strategy, Tokyo Institute of Technology, Japan

Resume : Charge compensation in zinc oxide has been discussed for many years. However, there still a lot of questions in detail, although many experimental and theoretical studies were conducted. At this situation, we realize that every experimental study were conducted with every different samples. Namely, there are a lot of reports with missing information: such as reports on transport property measurements without analyses of hydrogen concentration, mass transport study without minor impurity analysis. In order to reveal real nature of zinc oxide, it is necessary to characterize all possible parameters relating to charge compensation. To this context, we have performed analyses of impurity concentration and transport properties measurements on ZnO single crystals with different quality. In addition, to reveal the hydrogen related phenomena, annealing in ultra-high-vacuum and hydrogen ion implantation was also performed. The electric properties of ZnO in terms of defect formation and charge compensation will be discussed based on all those experimental results.

N.13.1
14:15
Authors : A. Turos*1&2, P. Jó?wik1, M. Wójcik1, J. Gaca1, R. Ratajczak2, A. Stonert2
Affiliations : 1)Institute of Electronic Materials Technology, Wolczynska 133, 01-919 Warsaw, Poland; 2)National Centre for Nuclear Research, Soltana 7, 05-400 Otwock, Poland

Resume : Ion beam induced defect processes in wide bandgap compound semiconductors are rather complex because of the formation of different types of defects and their transformations. In this paper we report results of the study on the mechanism of defect formation, migration and agglomeration in 300 keV Ar-ion bombarded ZnO single crystals. RBS/c analysis performed with the use of the unique McChasy code allowed determination of depth distributions for different defect types separately. Complementary HRXRD analysis was applied to study lattice deformation due to ion bombardment. It has been observed that migration of simple defects and their agglomeration lead to the formation of two types of dislocation loops: basal loops located at the depth corresponding to the range of incident Ar ions and pyramidal loops located beyond the ion range. The stress induced by defects in the bombarded layer has been identified as the driving force for defect migration and loop formation. As soon as the critical stress is attained bombarded layer undergoes plastic deformation resulting in the formation of a dense dislocation tangle.

N.13.2
14:45
Authors : Esteban Rucavado, Quentin Jeangros, Daniel F. Urban, Jakub Holovský, Federica Landucci, Aïcha Hessler-Wyser, Takashi Koida, Monica Morales-Masis, Christophe Ballif.
Affiliations : Esteban Rucavado, École Polytechnique Fédérale de Lausanne (EPFL); Quentin Jeangros, École Polytechnique Fédérale de Lausanne (EPFL); Daniel F. Urban, Fraunhofer Institute for Mechanics of Materials (IWM); Jakub Holovský, Czech Technical University (CTU); Federica Landucci, École Polytechnique Fédérale de Lausanne (EPFL); Aïcha Hessler-Wyser, École Polytechnique Fédérale de Lausanne (EPFL); Takashi Koida, National Institute of Advanced Industrial Science and Technology (AIST); Monica Morales-Masis, École Polytechnique Fédérale de Lausanne (EPFL); Christophe Ballif, École Polytechnique Fédérale de Lausanne (EPFL).

Resume : Transparent conductive oxides (TCOs) are essential components of numerous optoelectronic devices such as light emitting diodes and solar cells. Historically, indium-based materials have dominated the TCO market due to their good optoelectronic properties and their compatibility with a wide range of substrates. Nonetheless, alternatives must be developed as indium is a scarce element. Amorphous zinc tin oxide (ZTO) is a wide band gap alloy that has proven to be a promising alternative to replace In-based materials from various devices.[1,2] However, its optoelectronic properties must be further improved to expand its applicability. In this work, experimental and computational techniques are used to understand the defects limiting electron transport in ZTO. ZTO films were annealed systematically in oxidizing and reducing atmospheres and their optoelectronic and structural properties were characterized. Using density functional theory, it was found that oxygen vacancies (Vo) and hydrogen play a crucial role in the resulting properties of ZTO. While Vo are the main intrinsic dopant in ZTO, their presence limits the electron mobility and creates absorption centers in the visible range of the spectrum [3]. We demonstrate that these defects can be suppressed by either a thermal treatment > 400 °C in oxygen-rich atmospheres3 or at low-temperatures (< 200 °C) by co-sputtering4 ZTO with SiO2. Interestingly, co-sputtering with SiO2 decreases the subgap absorption without detrimental effects on the electrical properties. Motivated by the versatility of co-sputtering, ZTO-SiO2 is furthermore co-deposited Zr-doped In2O3, to create a reduced In-content film with excellent optoelectronic properties, hence with a broad application range.

N.13.3
15:00
Authors : S. Benedetti1, A. di Bona,1 G. Vinai3, S. Valeri1,2, A. Catellani1, A. Ruini1,2, P. Torelli3, A. Calzolari1
Affiliations : 1 CNR, Istituto Nanoscienze, Via G. Campi 213/a, 41125 Modena, Italy; 2 Dipartimento di Scienze Fisiche, Informatiche e Matematiche, Universita? di Modena e Reggio Emilia, via Campi 213/a, 41125 Modena, Italy; 3 Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza, I-34149 Trieste, Italy;

Resume : Transparent Conducting Oxides have gained large interest because of the peculiar combination of high transparency and low electric resistivity, with applications in optoelectronic and plasmonic devices.[1] Their properties can be largely modified by inclusion of dopants in wide-band gap semiconductors over a large range of concentration (like in Al-doped ZnO). However, the presence of structural defects results in an unpredictable complexity that prevents a clear identification of chemical and structural properties of the films, thus their identification and control is highly desirable. We have exploited the chemical sensitivity of Hard X-ray Photoelectron Spectra and Near Edge X-ray Absorption Fine Structure in combination with DFT to determine the spectroscopic response of defects in Al:ZnO films. Modifications in O1s and O K-edge have allowed to determine the concentration of embedded H, Zn vacancies and O interstitials in undoped ZnO. Contributions coming from substitutional and interstitial Al atoms have been identified and related to changes in the oxide stoichiometry and an increased oxygen coordination, together with small lattice distortions.[2] Consequences on the optical response in the UV-VIS and IR and band populations are discussed. This provides a tool to control defects and doping and improve the performance of TCO films. [1] K. Ellmer, Nature Photonics 6, 809 (2012). [2] I. Valenti et al., J. Appl. Phys. 118, 165304 (2015); S. Benedetti et al., submitted.

N.13.4
15:15
Authors : Holger Beh(1), Daniel Hiller(1), Michael Bruns(2), Alexander Welle(3), Hans-Werner Becker(4), Birger Berghoff(5), Christoph Sürgers(6), Margit Zacharias(1)
Affiliations : (1)IMTEK, Faculty of Engineering, Albert Ludwigs University Freiburg, Georges Köhler Allee 103, 79110 Freiburg, Germany (2)Karlsruhe Institute of Technology, Institute for Applied Materials & Karlsruhe Nano Micro Facility, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany (3)Karlsruhe Institute of Technology, Institute of Functional Interfaces & Karlsruhe Nano Micro Facility, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany (4)RUBION, Zentrale Einrichtung für Ionenstrahlen und Radionuklide, Ruhr-Universität Bochum, Universitätsstr. 150, 44780 Bochum, Germany (5)RWTH Aachen University, Institute of Semiconductor Electronics, Sommerfeldstr. 18, 52074 Aachen, Germany (6)Karlsruhe Institute of Technology, Physikalisches Institut, Wolfgang Gaede Str. 1, 76131 Karlsruhe, Germany

Resume : The origin of conductivity in intrinsically conductive atomic layer deposited (ALD) ZnO is still a subject of controversial discussion. To solve this problem, the three candidates for providing shallow donor states are investigated: intrinsic point defects, elemental impurities and hydrogen. Impurities other than hydrogen are ruled out due to their ultra-low concentrations in the ppm range. Intrinsic point defects are also considered unlikely since the evolution of conductivity with deposition temperature is not reproduced in the Zn/O ratio as measured by Rutherford backscattering spectrometry. Hence, the most promising candidate is hydrogen with a concentration of 1 at%, which is more than sufficient to account for the free electron density (up to 5x10^19 1/cm³). The formation energy of the conductive, hydrogen-related state is determined to be 40 meV. Hall measurements down to liquid helium temperatures revealed that the electron densities are constant over the whole temperature range. This constitutes a quasi-metallic behavior of ALD-ZnO for deposition temperatures of ? 150 °C. Ref.: Beh et al., J. Appl. Phys (under review)

N.13.5
15:30 Coffee break    
 
Session 14: New Materials : Andrzej Turos (Poland)
16:00
Authors : Yu-Feng Yao, Chun-Han Lin, Jia-Yu Liao, Huang-Hui Lin, Shaobo Yang, Keng-Ping Chou, Hao-Tsung Chen, Chia-Ying Su, Charng-Gan Tu, C. C. Yang
Affiliations : National Taiwan University, Taipei, Taiwan

Resume : Ga-doped ZnO (GaZnO) nanoneedles (NNs) are grown with the vapor-liquid-solid mode of molecular beam epitaxy by using Ag nanoparticles as growth catalyst. Based on the effective refractive-index effect, such GaZnO NNs can produce the function of anti-reflection for solar cell application. However, such a function relies on the orientation distribution of the NNs. In this paper, we first demonstrate the dependencies of light reflection and transmission on the orientation distribution of GaZnO NNs. Parallel and vertical GaZnO NNs on a device surface can lead to a stronger anti-reflection effect. Then, we disclose the mechanism of controlling the growth direction of a GaZnO NN. In particular, we show the relation between the crystalline structures of GaZnO and catalytic Ag. It is found that ZnO (002) plane always coincides with Ag (111) plane. The Ag crystalline orientation is controlled by the used substrate. For Si solar cell application, GaZnO NNs are randomly oriented on Si (100). To improve the orientation uniformity of GaZnO NNs for enhancing the anti-reflection effect, GaZnO NNs are grown after a GaZnO thin film is first deposited on Si (100). On this partly c-plane-oriented thin film, GaZnO NNs become more parallel and vertical, leading to a stronger anti-reflection effect. Based on the solar cell fabrication results, such a GaZnO NN structure can enhance the energy conversion efficiency of a Si solar cell by 33 %.

N.14.1
16:15
Authors : A. Alexander, J. Mannering, C. Hussene, M. J. Bennett and M. G. Francesconi
Affiliations : University of Hull (UK) University of Leeds (UK)

Resume : Materials that change colour with light carry large potential for technological applications. For example, in 1727 H. J. Schulze discovered that silver salts change colour when exposed to sun light, the starting point for the invention of photography. Recently, we discovered that polycrystalline samples of Nd2Ti2O7 show an instantaneous and totally reversible change of colour when exposed to different sources of light. In particular, Nd2Ti2O7 powders appear purple under visible light but rapidly switches to green if exposed to fluorescent light. This effect may be related to the ?Alexandrite effect? found first in the mineral Alexandrite, BeAl2O4, doped with a small amount of Cr3+, but was also observed in Nd3Li5Ta2O12, in Nd3+ containing minerals, such as Monazite, and even in Nd2O3. It can be therefore assumed that the dichroism shown by Nd2Ti2O7 is due to the presence of Nd. We have discovered that the colour can be tuned and the phenomenon of colour switching can be suppressed via chemical substitution on the Nd3+ and the O2? sites. We also studied alternative synthesis methods to the conventional solid-state approach to prepare single-phase samples, yet using lower temperatures and obtaining a homogeneous distribution of the particle size. UV-vis spectra are discussed. We believe that this optical phenomenon of color changing coupled with the well-documented ferroelectric and piezoelectric properties of Nd2Ti2O7 and similar titanates can lead to interesting applications.

N.14.2
16:30
Authors : Yew Hoong Wong, Kian Heng Goh, and A.S.M.A. Haseeb
Affiliations : Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia.

Resume : In this work, pure samarium metal thin film was sputtered on silicon substrates followed by thermal oxidation in oxygen (samarium oxide) and thermal oxynitridation in nitrous oxide (samarium oxynitride), respectively. Various characterization techniques such as X-ray diffraction, Fourier transformed infrared spectroscopy analysis, Raman analysis, high resolution transmission electron microscopy, capacitance-voltage measurements, leakage current density-electric field measurements, and trap-assisted tunneling analysis were carried out to evaluate and compare the structural, chemical, and electrical properties of the both films. It proved that the incorporation of nitrogen improved and enhanced the electrical properties by the passivation of silicon bond and stabilization of oxygen ions.

N.14.3
16:45
Authors : Güne? K?BAR 1,2 Ali Tuncel 2,3
Affiliations : 1.Department of Materials Engineering, Adana Science and Technology University, 01180, Adana,Turkey 2. Bioengineering Division, Hacettepe University, 06800, Ankara, Turkey 3. Division of Nanotechnology and Nanomedicine, Hacettepe University, 06800, Ankara, Turkey

Resume : In recent years, the great interest of nano- and micro-particle studies has given an opportunity to make further researches on material science with their advance physical, chemical, optical and biological properties potentially used in biomedicine, drug delivery, catalysis, sensor technology, and energy unit cells. Particularly, noble metal based nanoparticles have superior characteristics for many chemical reactions utilized as catalysts with high surface to volume ratio. As an important family of catalysts, gold nanoparticles (AuNPs) are attractive because high surface energy gives an efficient catalytic reaction in different particle size whereas bulk gold is often a passive catalyst. Besides all beneficial features, working with NPs is really difficult because the tendency to aggregation damages the shape and the surface states of AuNPs and undesirably decreases the catalytic activity. The objective of this study was to fabricate multifunctional microbeads to use for removal of environmental pollutants. By this aim, carboxyl carrier polymeric microbeads poly(mono-2-(methacryloyloxy) ethyl succinate -co- glycerol dimethacrylate) ?poly MMES-co-GDMA)? were synthesized monosized in 5µm diameter. Then iron oxide nanoparticles were attached on polymeric microbeads to obtain superparamagnetic properties to collect microbeads from removal media. At the last step, magnetic polymeric microbeads were decorated with AuNPs produced approximately 15nm in size. The obtained monodisperse gold catalyst with magnetic properties and polymeric template gave several advantages in catalytic system such as easy handling comparing with nanoparticle (no aggregation problem), separation from media with natural magnets and reuse of catalyst without leaching metals. The fabricated gold catalyst was characterized with scanning electron microscope (SEM), vibrating sample magnetometer (VSM), XRD and EDAX. As we know, environmental safety has a vital importance in human life and one of the important issue for world heritage. There are many regulation authorities around the world to keep environment in safe positon such as Environmental Protection Agency (EPA). This organization choose 4-nitrophenol (4-NP) one of the organic contaminants listed as priority pollutant because of highly soluble and having good stability in water. The newly fabricated gold catalyst was used to remove this organic substance from water medium. The degradation process of 4-NP to 4-aminophenol (4-AP) was monitored by UV-visible spectrometer. The parameters of the removal system were determined as concentration of catalyst, concentration of 4-NP and temperature of the media. The gold catalyst was collected by a powerful natural magnet for each experimental design. The reusability was test for fabricated material. The results were successful with high catalytic activity for several time the degradation of 4-NP to 4-aminophenol form in few seconds by using fabricated microbeads.

N.14.4
17:00
Authors : Matthew J. Bennett, David M. Benoit, Ian Dobson and M. Grazia Francesconi
Affiliations : Chemistry, School of Mathematics and Physical Sciences, Hull, United Kingdom

Resume : In the field of carbon dioxide capture and storage, two well-researched approaches are the reaction of alkali earth metal oxides, CaO to form metal carbonates and, the physisorption of CO2 in the channels of zeolites. We investigate a new approach that merges these strategies and aims to the preparation of novel carbonate-based materials. Oxides of the general formula A2CuO3 (A = Ca, Sr, Ba) contain alkali metals, which tend to react readily with CO2 to form stable carbonates and, also show a crystal structure with anion vacancies, which can mimic the cavities in zeolites and be host sites for CO2. We exploit the simultaneous presence of vacant sites and alkaline earth metals to form oxide-carbonates via reaction with CO2. A2CuO3 (A=Sr, Ca) compounds were reported to ?host? F? anion via fluorination, leading to A2CuO2F2 ?, (0???0.35), with A2CuO2F2 ? showing High Tc superconductivity. Sr2CuO3 can form the oxide carbonate Sr2CuO2(CO3) as a result of Sr-O groups reacting with CO2 to form metal carbonates. We were able to prepare Sr2CuO2(CO3), Sr1.8Ba0.2CuO2(CO3) and Sr1.5Ca0.5CuO2(CO3) via the direct reaction of Sr2CuO3 with CO2. We also studied the reaction of compounds isostructural to A2CuO3, A2PdO3 (A = Ba, Sr) and Ce2MnN3. We have monitored the incorporation of CO2 using a combination of Thermo Gravimetric Analysis, Powder X-Ray Diffraction and studied the reaction via DFT. The removal of CO2 to reform Sr2CuO3 was also carried out under O2, over multiple cycles.

N.14.5
17:15
Authors : Nakarin Subjalearndee1 and Varol Intasanta1*
Affiliations : 1Nano Functional Textile Laboratory (NFT), National Nanotechnology Center, National Science and Technology Development Agency (NSTDA), Thailand.

Resume : Fragility of inorganic materials is a fundamental problem and considered disadvantage in various applications where physical integrity must take crucial role in processing versatility, efficiency and recoverability. In this present research, we successfully fabricate stable metal oxide photocatalytic nanofibrous membrane as a representative physical integrity solution. Experimentally, we formulate a stable multicomponent metal complex solution for electrospinning followed a specific two-step thermal treatment. During calcination process, we investigate the duration, heating rate and temperature under structural confinement in order to obtain the stable metal oxide nanofibrous membrane. We discover the unfamiliar phenomena of metal oxide?s phase separation after calcination at more than 600 °C with ZnWO4 nanorods stemming out of the TiO2-ZnWO4 nanofiber?s surface. Furthermore, we successfully fabricate as-designed and stable metal oxide nanofibrous membrane through a continuous two-step calcination under unique environment provided by fiber glass confinement technique. It is observed that crosslinking among calcined nanofibers under different confinement conditions represents a physical origin of the membrane?s dimensional stability. We also show that the resulted metal oxide nanofibers could be decorated with Pd and Pt nanoparticles via facile and solution-based photoreduction. Both types of nanofibers, ZnWO4-TiO2 and Pd/Pt- ZnWO4-TiO2, show exceptional MB degradation efficiency within 15 minutes of the reaction under natural sunlight irradiation. In addition, ZnWO4-TiO2 nanofibers show promising benzene decomposition efficiency under visible light irradiation at room temperature.

N.14.6
17:30
Authors : Changan Wang 1, Parul Pandey 1, Pei-Chun Wang 2, Ping-Chun Wu 2, Mao Wang 1, Chi Xu 1, Yujia Zeng 3, Roman Böttger 1, Manfred Helm 1, Ying-Hao Chu 2, Shengqiang Zhou 1
Affiliations : 1) Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstr. 400, 01328 Dresden, Germany 2) Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan 3) Shenzhen Key Laboratory of Laser Engineering, College of Optoelectronic Engineering, Shenzhen University, 518060 Shenzhen, China

Resume : Complex oxides are fascinating materials, in which the manipulation of charge, orbital and lattice degrees of freedom leads to numerous exciting phenomena. We report here the use of He ion irradiation to control the out-of-plane lattice constant of epitaxial LaNiO3 (LNO) thin films independently without a change of the in-plane lattice constant. All the LNO films with the fluence less than 1×1015 He/cm2 exhibit metallic behaviors along with a slight resistivity upturn at low temperature, whereas the film with 2.5×1015 He/cm2 shows metallicity at high temperature and insulator-like behavior at low temperature. Further, the fitting for the temperature dependent resistance indicates that electrical-conductivity carriers are mainly scattered by electron-boson interactions rather than electron-electron interactions. These results suggest that He ion irradiation can be an alternative route to tune the functionality of complex oxides.

N.14.7

Symposium organizers
Albena PASKALEVAInstitute of Solid State Physics

Bulgarian Academy of Sciences, Sofia, Bulgaria

+359 2 979 5742
paskaleva@issp.bas.bg
Elżbieta GUZIEWICZ (Main organizer)

Institute of Physics - PAS Al. Lotnikow 32 /46 , PL - 02668 Warsaw, Poland

+48 2211633 29
guzel@ifpan.edu.pl
Lars ÖSTERLUNDUppsala University

Engineering Sciences, The Ångström Laboratory, Box 534, SE-751 21 Uppsala, Sweden

+ 46 18 4716383
lars.osterlund@angstrom.uu.se
Mato KNEZCIC nanoGUNE and IKERBASQUE

Basque Foundation of science - San Sebastian, Spain

+34 943 574 040
m.knez@nanogune.eu