preview all symposia

2015 Fall

Characterization of materials by experiments and computing

V

Stress, structure, and stoichiometry effects on the properties of nanomaterials

Nanomaterials and nanostructures are playing an increasing role in everyday life as part of complex (miniaturized) electronic devices but also as components of modern tools for diagnosis and treatment in medicine. Because of that, preparation and characterization of well controlled, at the nanoscale size, of complex nanomaterials and nanostructures is of paramount importance for their applications. The proposed symposium provides an interdisciplinary forum to discuss recent progress in the area of production, characterization and principal applications of nanomaterials and nanostructures.

 

Scope

 

It is proposed a symposium that will be the follow-up of the two symposia “Stress, structure and stoichiometry, effects on the properties of nanomaterials”, held at the E-MRS Fall Meetings of 2011 and 2013 with very good attendance. Nanomaterials play now a crucial role in most aspects of advanced technologies, because of their surprising variety of functional properties. These properties can be finely tuned with a vast multitude of physical and chemical synthesis techniques. In particular, structure and stoichiometry are the key ingredients in this tuning at the nanometer scale. Stress, chemical phase and presence of defects and dislocations are critical factors governing the (nano)fabrication procedures; the investigation of their influence on the electric, magnetic optical and mechanical properties of the ever growing collection of nanosystems is a crucial challenge in material science, and it is also necessary for the engineering of the new devices to be realized for future applications. The scope of the symposium is to provide a forum for presentation and discussion of innovative methods in fabrication, characterization and modelling of nanomaterials and nanostructures: ultrathin films, nanotubes, nanopillars, nanowires, nanoparticles, with emphasis on influence of stress and stoichiometry on their properties.

 

Hot topics to be covered by the symposium

 

  • Influence of the deposition process on the structure of nanomaterials
  • Heterostructures and superlattices
  • Investigations and engineering of interfaces in nanomaterials for enhanced properties 
  • Advances in small scale characterization techniques
  • Use of self-organization and templates to grow nanostructures
  • Strain control and its effects on functional properties
  • Atomistic models for stress and defects in nanostructures
  • Interface effects in magnetic, optical and electric properties of nanosystems
  • Measuring and modeling friction at moving interfaces

 

 

Tentative list of invited speakers

 

  • Chantal Leborgne: GREMI , Orleans, France
  • Paolo Ossi, Politechnico di Milano, Italy, From isolated particles to nanoparticle arrays: laser tailored film nanostructures to identify molecules at diluted concentrations
  • Valentin Craciun, INFLPR, Bucharest, Romania
  • Florencio Sanchez, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Spain 
  •  Dhananjay Kumar, North Carolina A & t State University, USA
  • Fabien Paumier, Institut Pprime – CNRS, University of Poitiers, France
  • Chi Lun Pang Chemistry Dept. University College London, UK
  • Giordano, Dipartimento Scienza dei Materiali, Università di Milano Bicocca (computational, ultrathin oxide films)

 

Tentative list of scientific committee members

 

J. Moser (Spain), E. Garnet (Denmark), F. Ruffino (Italy), S. Cabrini (USA), D. Drouin (Canada), M. Schnabel (Germany), G. Leonhard (Austria), I. Boarino (Italy), M. Laus (Italy), G. Fleury (France), Paola Luches (Italy), Dimitis Niarchos (Greece), Socrates Pantelides (USA), Raluca Muller (Romania)

 

The symposium will be co-organized by the EU 7-th Framework Programme under the project REGPOT-CT-2013-316014(EAgLE). 

Start atSubject View AllNum.
09:00 V and W Symposia Joint Sessions Opening: T. Dietl, M. Dinescu    
 
V and W Symposia Joint Session 1 : chair Ewa Jedryka
09:10
Authors : Alberta Bonanni
Affiliations : JKU Institute of Semiconductor and Solid State Physics

Resume : We summarize our recent work on the fabrication of III-nitrides doped with transition metals, with particular focus on the self-aggregation driven by fabrication parameters and co-doping [1] of functional magnetic nanocrystals [2-5], layered heterostructures [6,7] and magnetooptically active complexes [8,9]. An overview will be given on how we have unraveled and we can now control the correlation between the growth parameters and structural architecture, self-assembling of embedded crystalline nanostructures and phase separation that determine the magnetic, electric and optical response of the modulated systems. The work was supported by the European Research Council (ERC, Project #227690), by the Austrian Science Fundation (FWF, Projects #20065, #22477, #24471), by WRC ETI+ (Project NanoMat, P2IG.01.01.02-02-002/08 and the European Operational Programme Innovative Economy) and by the CAPACITIES project REGPOT-CT-2013-316014 (EAgLE). [1] A. Bonanni and T. Dietl, Chem. Soc. Rev. 39, 528 (2010). [2] A. Bonanni et al., Phys. Rev. Lett. 101, 135502 (2008). [3] A. Navarro-Quezada et al., Phys. Rev. B 81, 205206 (2010). [4] A. Navarro-Quezada et al., Phys. Rev. B 84, 155321 (2011). [5] A. Grois et al., Nanotechnology 25, 395704 (2014). [6] T. Devillers et al., Cryst. Growth Des. 15, 587 (2015). [7] M. Rovezzi et al., arXiv1412.3932 [8] T. Devillers et al., Scientific Reports 2, 722 (2012). [9] T. Devillers et al., Appl. Phys. Lett. 103, 211909 (2013).

V.1.1
09:40
Authors : Fei Wang, Sergei Simak, Magnus Odén, Igor A. Abrikosov, Ferenc Tasnádi
Affiliations : Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping, Sweden

Resume : Design of micro- and nanostructured materials is a sector in materials science with strong connection to cutting-edge technology. Superhard materials are developed in the form of superlattices and the hardness enhancement is explained by the hindered dislocation motion controlled by the materials microstructure and the accumulated coherency strain. By spinodal decomposition the metastable c-Ti1-xAlxN transforms to nano-sized domains rich in AlN and TiN, which results in improved mechanical properties [1]. TiAlN/TiN coatings have been suggested as an alternative by combining the best properties of TiN and TiAlN. Extended thermal stability, higher oxidation and wear resistance have been obtained [2]. The details of the isostructural decomposition in the multilayers and the impact of the interfacial effects are not fully understood. In this work we extend the approach by Ozoliņš [3] to multilayers of alloys to investigate the thermodynamics of TiN/Ti1- xAlxN(100). The results are compared with calculations performed for the related Ti1- xAlxN bulk. It is shown the mixing enthalpy of multilayer is suppressed by both constituent strain and interface chemistry equally, which lead to different phase stability in comparison with the bulk. We predict that the compositional variation of this decrease correlates with shape of the bulk mixing enthalpy of Ti1-xAlxN that is the largest suppression is derived at the composition where the bulk mixing enthalpy has a maximum. In addition, we find that the local lattice relaxations along z direction at the interface become more substantial with increasing Al composition in TiAlN slab. The Ti and N atoms show large relaxations at the interface of the multilayer when there is higher Al composition, while Al atoms remain small relaxations regardless of Al composition. [1]. A. Hörling, L. Hultman, M. Odén, J. Sjölén, and L. Karlsson, Surface and Coatings Technology 191, 384 (2005). [2]. M. Nordin, R. Sundström, T. Selinder, and S. Hogmark, Surface and Coatings Technology 133–134, 240 (2000). [3]. V. Ozoliņš, C. Wolverton and A. Zunger. Phys. Rev. B 57, 4816 (1998)

V.1.2
10:00
Authors : Matthieu JAMET
Affiliations : Univ. Grenoble Alpes, INAC-SP2M, F-38000 Grenoble, France. CEA, INAC-SP2M, F-38054 Grenoble, France.

Resume : The field of ferromagnetic semiconductors evolves very fast nowadays for their potential use in spintronic devices. Up to now, efforts have mainly focused on Diluted Magnetic Semiconductors but Curie temperatures in these materials still remain modest. One possible route to increase at least locally transition temperatures is to use spinodal nanodecomposition leading to the formation of transition metal-rich high-TC nanostructures [1]. We focus here on (Ge,Mn) considered as a model system for spinodal decomposition and compatible with Si-based microelectronics. (Ge,Mn) films grown on Ge substrates by molecular beam epitaxy at low temperature (<180°C) are free from secondary phase and contain self-assembled Mn-rich nanocolumns exhibiting high-TC [2]. In this talk, I will present a complete phase diagram of nanocolumns as a function of the substrate (Ge, GaAs) and growth temperature, Mn concentration and Sn co-doping focusing on their size, density, composition, morphology, crystalline structure and magnetic properties. For this purpose, we have used highly sensitive techniques at large scale facilities like synchrotron radiation based x-ray diffusion, diffraction and absorption, atom probe tomography, low energy muons spectroscopy and small angle neutron scattering. Only these techniques allowed us to probe in detail the physical properties at the nanoscale in the spinodally decomposed (Ge,Mn) system. [1] T. Dietl, K. Sato, T. Kukushima, A. Bonanni, M. Jamet, A. Barski, S. Kuroda, M. Tanaka, P. N. Hai, H. Katayama-Yoshida, arXiv: 1412.8062, accepted in Rev. Mod. Phys. (2015) [2] M. Jamet, A. Barski, T. Devillers, V. Poydenot, R. Dujardin, P. Bayle-Guillemaud, J. Rothman, E. Bellet-Amalric, A. Marty, J. Cibert, R. Mattana, S. Tatarenko, Nat. Mater. 5, 653 (2006).

V.1.3
10:30 Coffee break    
 
V and W Symposia Joint Session 2 : chair Alberta Bonanni
11:00
Authors : L. Michez 1, F. D?Acapito 2, E. Prestat 3, M. Jamet 3, F. Boscherini 4, M. Petit 1, V. Le Thanh 1
Affiliations : 1 Aix-Marseille Universit? - CNRS CINaM-UMR, 13288 Marseille, France 2 ESRF, 38043 Grenoble, France 3 INAC/SP2M, CEA-Grenoble, Grenoble, France 4 University of Bologna, 40127 Bologna, Italy

Resume : Much attention has been recently devoted to Mn5Ge3 as this compound meets all the requirements for spin-polarized transport and injection into Ge. This material may therefore represent a new route to develop the beyond complementary metal-oxide-semiconductor technology. Its limited Curie temperature (TC~296K) greatly hinders its use for potential applications but can be enhanced up to 450K by incorporating a small amount of carbon. Theoretical calculations attribute this behavior to an enhancement of the Mn-Mn interactions mediated by C atoms placed in interstitial sites. In this work, we have extensively studied the structural and magnetic properties of Mn5Ge3Cx films grown on Ge(111) by molecular beam epitaxy as a function of C concentration. Besides the compressive strain induced by the incorporation of C, the latter modifies significantly the Mn5Ge3 magnetic properties. Whereas Tc increases from 296K to 450K, the magnetocrystalline anisotropy in C-doped samples is reduced by nearly a factor 10 as x is increased from 0 to 0.7. This effect is assigned to hybridization between Mn and C atoms whose position has been investigated via EXAFS and STEM experiments. The magnetic properties of carbon-doped Mn5Ge3Cx thin films can therefore be tuned by adjusting the amount of C. This is very promising for the realization of spintronics devices and in addition, the presence of C is essential for the thermal stability and the high performances of Mn5Ge3 thin films.

V.2.1
11:30
Authors : R. Kalvig(1), E. Jędryka(1), M. Wójcik(1), W. Bednarski(2), L. A. Michez(3), M. Petit(3), V. Le Thanh(3)
Affiliations : (1) Institute of Physics PAN, Al. Lotników 32/46, 02-668 Warszawa, Poland ; (2) Institute of Molecular Physics PAN, ul. M. Smoluchowskiego 17, 60-179 Poznań, Poland; (3) CINaM – CNRS UPR 3118, Campus de Luminy, Case 913, 13288 Marseille Cedex 9, France

Resume : Ferromagnetic Mn5Ge3 compound is of particular interest for spintronic applications, mainly due to high spin polarization of the conduction electrons (42%) and compatibility with the mainstream silicon technology. Interestingly, it has been observed that the addition of carbon increases the Curie temperature from 296 K in case of pristine Mn5Ge3 up to 445 K in Mn5Ge3C0.6. In order to understand the role that carbon plays in this system, the magnetocrystalline anisotropy was studied in a series of epitaxial 30 nm thick Mn5Ge3Cx films with carbon content varying between 0

V.2.2
11:50
Authors : Markus Gellesch, Franziska Hammerath, Marcel Haft, Silke Hampel, Sabine Wurmehl, Bernd Büchner
Affiliations : Institut für Festkörperforschung, IFW Dresden; Institut für Festkörperphysik, TU Dresden

Resume : Identification of stoichiometry in nanoscale system is a crucial issue in order to establish a working composition/structure-property-relationship. Commonly, transmission electron microscopy (TEM) equipped with diffraction tools is applied to determine stoichiometry and structure in nanomaterials. However, this approach usually allows investigations of a selected part of a sample and obtaining significant statistics demands a high effort. Especially in multi-component samples the application of complementary methods is helpful. Here, we present a combined approach of TEM-based methods with 59Co nuclear magnetic resonance (NMR) to obtain an in-depth understanding of composition and structure in Heusler-based nanoparticle systems. We use TEM-EDX studies of individual particles to obtain information on local stoichiometry and structure. With 59Co NMR we can identify phases based on their characteristic resonance frequencies originating from the local atomic environments and, further, estimate the amount of each phase. As NMR spectra can be measured from a complete sample batch it provides global information and statistics on compositions and structures. The combination of both, local TEM-based methods and global NMR measurements, sheds light on compositions and structures with significant statistics. From our investigations we find that this combination is a powerful tool to characterize magnetic nanoparticle assemblies.

V.2.3
12:10
Authors : Irene Villa†, Anna Vedda†, Markus Niederberger‡, Alessandro Lauria‡*
Affiliations : †: Department of Materials Science, University of Milano-Bicocca, Via R. Cozzi 55, 20125 Milano, Italy. ‡: Laboratory for Multifunctional Materials, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland.

Resume : In this work we report the tunable optical features observed in undoped monoclinic HfO2 nanocrystals and their dependence on the structural properties of the material at the nanoscale. Transmission electron microscopy together with X-ray diffraction and surface area measurements were used to determine the fine structural modifications, in terms of crystal growth and coalescence of crystalline domains, occurring during a calcination process in the temperature range from 400 to 1000 °C. The fit of the broad optical emission into spectral components, together with time resolved photoluminescence, allowed us to identify the dual nature of the emission at 2.5 eV, where an ultrafast defect-related intrinsic luminescence (with decay time of few ns) overlaps with a slower emission (decay of several s) due to extrinsic Ti - impurity centres. Moreover, the evolution of intrinsic visible bands during the material transformation was monitored. The relationship between structural parameters uniquely occurring in nanosized materials and the optical properties was investigated and tentatively modelled. The blue emissions at 2.5 and 2.9 eV are clearly related to defects lying at grain boundaries, while an unprecedented emission at 2.1 eV enables, at relatively low calcination temperatures, the white luminescence of HfO2 under near-UV excitation.

V.2.4
12:30 Lunch break    
 
V and W Symposia Joint Session 3 : chair Liza Michez
14:00
Authors : Mariana Stefan, Sergiu V. Nistor, Daniela Ghica
Affiliations : National Institute of Materials Physics, P.O. Box MG-7, 077125 Magurele, Romania

Resume : The synthesis of nanostructured semiconductors with material properties tailored for specific applications requires knowledge and control of structural aspects (size, morphology, crystallinity), impurity content and localization in the nanostructure. Electron paramagnetic resonance (EPR) spectroscopy can detect with high sensitivity the presence and amount of paramagnetic impurities in semiconductor nanostructures, determine the configuration of their neighboring ligands and the local structural/bonding modifications induced by thermo-chemical treatments. As shown in the particular case of nanostructured ZnO doped with Mn(II) ions, the resulting EPR spectra can be further used to gain insight on the local structure, crystallite size, degree of lattice disorder and the presence of separate phases. For ZnO nanoparticles doped with low concentrations of Mn(II) ions we have established an empirical relationship between the disorder induced changes in the EPR lines and the average crystallite size, independent of the synthesis procedure. Using this result we could further characterize various ZnO nanostructures. Thus, we have determined the mechanisms governing the nanocrystallization of the disordered ZnO prepared by the thermal decomposition of hydrozincite. In the case of nanostructured ZnO films we could quantitatively evaluate the amount of Mn(II) ions segregated at the grain boundaries and their distribution after annealing.

V.3.1
14:30
Authors : VICTOR JAYA NESAMONY
Affiliations : DEPARTMENT OF PHYSICS ANNA UNIVERSITY CHENNAI -25 INDIA

Resume : The nanotechnology deals with structures sized between 1 to 100 nm in at least one dimension. Today nanofibers are at the forefront of nanotechnology and has various applications in various fields. Their unique porous structures and large surface to volume area has different properties compared with bulk materials, make them suitable for a wide variety of applications. There are many ways to produce nanofibers. Electrospinning process to produce nanofibers is the one of the best method. The Electropinning process has gained the most attention not only because of its simplicity but also because it can produce nanofibers with different materials. The Electrospinning process is straightforward, producing very fine fibers from polymer solutions or from melts with the help of electrostatic forces. The ZnO nanofibers were synthesised using the electrospun from a solution that containing Poly 4-Vinyl Phenol and Zinc acetate dihydrate.The morphology,composition, and crystal structure of ZnO nanofibers were investigate by scanning electron microscope (SEM)),X-ray diffraction (XRD) and Raman Spectrum methods. This nano fiber is tested for sensing various gas.

V.3.2
14:45
Authors : Bastian Henne [1], Verena Ney [1], Katharina Ollefs [2], Fabrice Wilhelm [2], Andrei Rogalev [2], Andreas Ney [1]
Affiliations : [1] Johannes Kepler University Linz, Austria, [2] ESRF – The European Synchrotron Grenoble, France

Resume : Thin films of Zn_{x}Co_{1-x}O thins films were grown from the wurtzite n-type 60%Co:ZnO to the p-type spinel ZnCo2O4 site of the compositional range by reactive magnetron sputtering from one oxide composite target just by variation of the preparation conditions. In between the pure phases a coexistence phase was observed. The interplay between local structure, valence, carrier type and magnetism was thoroughly investigated using integral and synchrotron-based element-specific measurement techniques. X-ray absorption spectroscopy was used to study the valance, X-ray linear dichroism to study the local structure and X-ray magnetic circular dichroism to investigate the Co sublattice magnetization of the samples. Doing this provides a way to study the structural and magnetic properties of the Zn-Co-O system well above the coalescence limit of the cationic sublattice as well as in a p-type carrier environment. Throughout the sample series uncompensated antiferromagnetism was found as predominant coupling mechanism for both, the (cubic) ZnCo2O4 spinel and the wurtzite Co:ZnO.

V.3.3
15:00
Authors : D. A. Pawlak, M. Gajc, K. Sadecka, P. Osewski, K. Korzeb, S. Turczynski, K. Wysmułek, J. Sar
Affiliations : Institute of Electronic Materials Technology, Warsaw, Poland Centre of New Technologies, Warsaw University, Poland

Resume : Recent recognition that some materials (e.g. certain metals) have negative dielectric permittivities at frequencies below their plasma frequency, and therefore provide possibilities of fabricating hybrid materials of high impact for photonic applications, has caused rapid development of two new research areas: plasmonics and metamaterials. However, the fabrication of nanosized metallodielectric structures remains a challenge. Most current fabrication techniques arrange metal nanoelements on dielectric surfaces. The methods used are either time-consuming and costly (e.g. lithography), or restricted to the creation of two-dimensional structures at a limited production scale. One of the future ways of obtaining metamaterials or materials with unusual electromagnetic properties are the bottom-up manufacturing methods, which may enable manufacturing of two-dimensional and three-dimensional structures. Theoretical proposals for and experimental demonstrations of bottom-up approaches are scarce and exhibit drawbacks. Recently, we proposed the idea of utilizing directional solidification as a method for manufacturing metamaterials and plasmonic materials. We develop two methods: (i) method based on directionally-grown self-organized eutectic structures; and (ii) NanoParticles Direct Doping method (NPDD) based on directional solidification of dielectric matrices doped with various nanoparticles. In both of these methods we can easily use all available resonant phenomena to develop materials with unusual electromagnetic properties. Eutectics are simultaneously monolithic and multiphase materials forming self-organized micro/nanostructures, which enable: (i) the use of various component materials including oxides, semiconductors, metals, (ii) the generation of a gallery of geometrical motifs and (iii) control of the size of the structuring, often from the micro- to nanoregimes. On the other hand, the novel method of NanoParticles Direct Doping enables doping of dielectric matrices with various nanoparticles (varying chemical composition, size and shape) and with the possibility of co-doping with other chemical agents as eg. optically active rare earth ions or quantum dots. In both cases we apply one of the crystal growth methods - the micro-pulling down method - to create the material. This method has been originally developed for manufacturing of single crystalline fibres and than used for directional solidification of eutectics and finally for directional solidification of glasses. Utilizing described above methods we demonstrated (i) volumetric eutectic-based material with localized surface plasmon resonance at visible wavelengths; (ii) enhanced luminescence and up-conversion processes in the eutectic material exhibiting LSPR and co-doped with erbium ions; (iii) volumetric matrix-nanoparticles-based materials with plasmonic resonances at visible and IR wavelengths based on silver (Ag), antimony-tin-oxide (ATO) and titanium nitride nanoparticles (TiN); (iv) matrix-nanoparticles-based composite with enhanced photoluminescence at the telecommunication frequency of 1.5 µm; (v) material with subwavelength transmission at IR frequencies; (vi) material with anomalous refraction, evaluated by the beam deviation measurements; (vii) materials with enhanced Faraday effect; and (viii) materials for phonoanodes in photoelectrochemiacal cells for generation of hydrogen. All these results will be described. Our new approach based on utilizing the standard crystal growth methods combined with the bottom-up approach for manufacturing metamaterials and plasmonic materials leads to novel manufacturing solutions for applications in areas such as photonics, optoelectronics, photovoltaics and photoelectrochemistry.

V.3.4
15:30 Coffee break    
 
V and W Symposia Joint Session 4 : chair Chris Palmstrom
16:00
Authors : Paolo M. Ossi
Affiliations : Dipartimento di Energia, Politecnico di Milano, via Ponzio 34-3, 20133 Milano

Resume : By nanosecond pulsed laser ablation in ambient gas nanoparticles (NPs) form and grow in the propagating laser-generated plasma plume. Such NPs mutually self-assemble on a substrate producing elaborated architectures with controllable morphology and increasing thickness. Besides laser wavelength, target to substrate distance, gas nature and pressure, at fixed laser energy density the energy per pulse and the spot size strongly affect the amount of ablated matter and thus plume energetics. At landing on the substrate NP size, energy and mobility affect film growth, morphology and physico-chemical properties. Ag and Au targets were ablated in Ar (10-100 Pa), changing the pulse number (500-30000), keeping constant target to substrate distance, incidence angle, laser wavelength and energy density. Films consisting of NP arrays were deposited on various substrates. The morphology ranged from isolated NPs to island structures, as observed by SEM and TEM. From fast imaging of the plume the plasma propagation regime and its initial velocity were determined. This data and the measured average ablated mass per pulse allow to model in-plume NP growth. Controlling growth parameters NP aggregation is finely tuned to obtain high-performance Surface Enhanced Raman Scattering (SERS) substrates. Good sensitivity and reproducibility of the SERS signal was proved for the anti-Parkinsonian drug apomorphine, in aqueous and in biological solutions and for the anti-epileptic drug carbamazepine.

V.2.9
16:30
Authors : P. Camarda, L. Vaccaro, F. Messina, M. Cannas
Affiliations : Department of Physics and Chemistry, University of Palermo, Italy

Resume : Pulsed laser ablation in liquid phase (PLAL) is a versatile method to synthesize high-purity nanomaterials such as ZnO nanoparticles (NPs), currently the subject of a large scientific interest stimulated by their promising technological applications. They are characterized by two emission bands both excited above the energy gap (3.4 eV): 1) exciton related at 3.3 eV; 2) defect related at 2.3 eV, commonly attributed to oxygen vacancies. Existing studies have used only ex-situ methods to characterize the endproducts of PLAL; these approaches only provide indirect information on the sequence of reactions ultimately yielding stable metal oxide NPs. In this work, we report online absorption (OA) and photoluminescence (PL) measurements carried out during and after PLAL of a Zn plate in H2O. Our experimental setup is original in that it uses the kinetics of OA and PL signals to follow in real time the dynamics leading to the formation of ZnO. We demonstrate that initially-produced Zn NPs are not "instantaneously" oxidized within the plasma plume, but rather as consequence of their reactions with H2O. In fact, ZnO NPs are formed by a sequence of two steps: an early, defect-free superficial oxidation of Zn NPs, followed by a second slower oxidation of the Zn core, finally producing sub-stoichiometric ZnO NPs rich of oxygen vacancies. This information can be used to control the defect concentration allowing the tuning of PL band of the ZnO NPs.

V.2.10
16:45
Authors : B. Kalska-Szostko*, U. Wykowska*, D. Satuła#
Affiliations : * Institute of Chemistry, University of Bialystok, Hurtowa 1, 15-399 Białystok, Poland #Department of Physics, University of Bialystok, Ciolkowskiego 1L, 15-245 Białystok, Poland

Resume : Nowadays, nanotechnology is a broad field of action of both science and everyday life. Continuously new materials are discovered with amazing physical and chemical properties. In case of nanoparticles, especially magnetic one are of special interest last time. It was find out that the properties strongly depend on the composition of core but also on the type of surface layer. For example, doping of iron oxide nanoparticles with different 3d metals, changes their magnetic properties significantly. When iron oxide nanoparticles are doped with Mn, Ni, or Co it enhances ferromagnetic properties usually observed. On the other hand when non-magnetic metals are used (Zn, Al) nanoparticles exhibit rather superparamagnetic behaviour at RT [1]. In this presentation we would like to show, how magnetite nanoparticles properties changes, while inorganic core is modified with different metals. Presented analysis of these structures include TEM, EDX, X-ray diffraction, and Mössbauer spectroscopy studies. [1] B. Kalska-Szostko, U. Wykowska, D. Satuła, Applied Surface Science 360 (2014) 7-15

V.2.11
17:00
Authors : Thantip S. Krasienapibal, Tomoteru Fukumura, Hideyuki Kamisaka, Tetsuya Hasegawa
Affiliations : The University of Tokyo; Tohoku University, JST-CREST; The University of Tokyo, JST-CREST; The University of Tokyo, JST-CREST, Kanagawa Academy of Science and Technology

Resume : (Ti,Co)O2, is a high TC ferromagnetic oxide semiconductor. In this material, the carrier-mediated exchange interaction plays a principle role [1], however, the mechanism of high TC is still unclear. In order to investigate the mechanism, TC of anatase (Ti,Co)O2 as functions of varjous material parameters was systematically evaluated from transport and magnetization properties below TC. We also studied microscopic magnetic properties from the aspect of magnetic or structural inhomogeneity, proposed for possible high TC ferromagnetism [2]. By magnetic force microscopy at room temperature, maze-like domain was observed above threshold carrier density [3]. The presence of small magnetic hysteresis at low carrier density suggests a possible formation of ferromagnetic embryos. We discuss the effect of suboxidic structure in rutile (Ti,Co)O2 recently observed by fluorescent x-ray holography [4]. This suboxidic structure is an alternative scenario of nucleation center of magnetic polarons attracting electron carriers, instead of the formation of Ti3+-VO-Co complexes recently proposed [5]. References [1] Y. Yamada et al., Science 332, 1065 (2011). [2] T. Dietl et al., arXiv:1412.8062. [3] T. S. Krasienapibal et al., Appl. Phys. Lett. (2015) in press. [4] W. Hu et al., Appl. Phys. Lett. (2015) in press. [5] K. Griffin Roberts et al., Phys. Rev. B 78, 1 (2008). *This research is in part granted by NEXT Program and JSPS-KAKENHI. T. K. is supported by Marubun Research Promotion Foundation

V.2.12
17:15
Authors : Maciej Bialoglowski1, Michal Wrzecionek1, Grzegorz Matyszczak1, Piotr Dluzewski2, Patrycja Wrzosek3, Slawomir Podsiadlo1
Affiliations : 1 Faculty of Chemistry, Warsaw University of Technology; 2 Institute of Physics, Polish Academy of Sciences; 3 Faculty of Physics, Warsaw University of Technology

Resume : Photovoltaics is a major area of research within the field of renewable energy sources. Solar devices based on Cu2ZnSnS4 (CZTS) – a semiconductor, which crystallizes mostly in the kesterite structure, promise high performance, low-cost production and ecologically friendly terawatt application. This study has focused on synthesis and characterization of its derivatives, in which Zn has been substituted with magnetic elements, i.e. Mn, Fe, Co, and Ni. The syntheses have been carried out in organic solvents, using metal salts and sulfur. The obtained materials have been characterized with X-ray powder diffraction, Raman scattering spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy and spectrophotometry UV/Vis/NIR.

V.2.13
 
Poster Session 1 : chairs Sergio D'Addato, Mariana Stefan
17:30
Authors : Mounir Znaidi, Dhaou Gherouel, Imen Gaied, Mosbah Amlouk, Noureddine Yacoubi
Affiliations : (a)Institut Pr?paratoire Aux Etudes d?Ing?nieurs de Nabeul, Merazka, 8000 Nabeul, Tunisia (b)Unit? de Physique des Dispositifs ? Semi-conducteurs, Facult? des Sciences de Tunis, Tunis El Manar University, 2092 Tunis, Tunisia

Resume : In this paper, we report the effect of annealing time on the properties of CuIn (S1-xSex)2 compounds. The CuIn(S1-xSex)2 deposited films have been grown from CuInS2 (CIS) sprayed thin film which treated under seleneide atmosphere at 400?C during 30, 45, 90 and 120 mn. The structural properties of the resulting films were characterized by means of X-ray diffraction (XRD). The thermal conductivity and the thermal diffusivity were investigated by the photothermal deflection technique (PTD). We have found, with prolongation of annealing time, all films present CuIn (S1-xSex)2 in its chalcopyrite structure with preferred orientation along < 112> direction. XRD analysis shows the incorporation of Se element in the (CIS) matrix. The grain became higher in size; it lays in the range of 15 nm to 54nm. The thermal conductivity ?k? and the thermal diffusivity ?D? are decreased until 45mn annealing time then they are increased.

V.V I.1
17:30
Authors : L. Grządziel, M. Krzywiecki
Affiliations : Institute of Physics–CSE, Silesian University of Technology, Konarskiego 22B, 44-100 Gliwice, Poland

Resume : Perspective material for organic nanoelectronics development is group of metallophthalocyanine (MePc) thin films already applied in e.g. organic light emitting diodes, organic thin film field effect transistors, solar cells and gas sensors. Application of organic nanolayer is strongly dependent on the electronic and chemical properties of its surface. Operating in real-world conditions, these properties are modified due to contact with air. This interaction leads to adsorption of ambient atoms or molecules on MePc surface inducing charge transfer between them. Process affects organic chemical bonds manifesting change of surface chemical structure. It may provoke variation of electronic surface states occupation and modify electronic parameters. In work, the copper phthalocyanine (CuPc) thin films (16, 32, 500 nm thick) were deposited on different Si(111) substrates. Surface electronic parameters and chemical structure were investigated by ultraviolet and angle resolved X-ray photoelectron spectroscopies as well as by photoemission yield spectroscopy before and after air exposure, depending on substrate type. Collected electronic parameters changes were correlated with morphological features measured by atomic force microscopy. Studies indicated particular electronic tendency for oxidation processes for certain shapes of CuPc crystallites. Contaminating chemical species were recognized and underwent depth distribution analysis.

V.V I.2
17:30
Authors : Maxwell Ferreira Lobato 1; Carlson Pereira de Souza 1; Rafael Hernandez Damascena dos Passos 1; Andarair Gomes dos Santos 2
Affiliations : (1) Nanostructured Materials Laboratory and Catalytic Reactors – Federal University of Rio Grande do Norte, Lagoa Nova, Natal, RN, 59078-900. (2) Department of Agrotechnology and Social Sciences - Federal Rural University of Semi- arid , Av. Francisco Mota, 572, Costa e Silva, Mossoró, RN: 59.625-900.

Resume : In the study of the synthesis methods, the effect of the partial replacement of cerium (Ce) of the BaCeO3 perovskite by a transition metal indicates an increase in conductivity, producing an increase in oxygen vacancies, responsible for the permeation of some types of gases. Thus, the present study aimed to the synthesis and characterization of BaCeO3 and BaCe0,5Pr0,5O3 in order to identify the effect of partial replacement of praseodymium morphology and microstructure of the material analyzed for future applications in catalysis and gas permeation. Through the Rietveld refinement was observed that the material showed a crystal system orthorhombic with space group Pmcn beyond the crystallite size of approximately 126.7 nm to BaCeO3. Even with the partial replacement of 50% of the cerium by praseodymium, the DRX results showed intensity peaks close to those of the previous sample, in addition to the same intermediate phase. Through the Rietveld refinement was also found that the material has orthorhombic crystal system with space group Pmcn and crystallite size of 116.2 nm. The BET method shows the nitrogen physisorption isotherms related to perovskites BaCeO3 and BaCe0.5Pr0.5O3. The surface areas found for BaCeO3 and BaCe0.5Pr0.5O3 perovskites were, respectively, 2.61 g / m² and 3.03 g / m². Thus, it’s concluded the praseodymium changed the microstructure and morphology of binary material, decreasing the size of crystals and increase the surface area.

V.V I.3
17:30
Authors : R. А. Shkarban, Т. S. Dosenko, S. I. Sidorenko, Iu. N. Makogon
Affiliations : Kyiv Polytechnic Institute, National Technical University of Ukraine, 03056, Prospect Peremogy 37, Kyiv, Ukraine

Resume : Improving the efficiency of thermoelectric materials is possible through a use of nanoscaled materials, such as nanofilms. A promising material for research is considered to be the antimonide CoSb3 (skutterudite). Functioning of thermoelectric devices largely depends on stability of phase composition, microstructure and properties of thin films deposited on suitable substrates. In this paper, it is stated a relation between the phase composition, structure of the nanoscaled films based CoSb3 and residual stresses. The investigated 30-nm-thick CoSbх(3.6 ≤ х ≤ 4.2) films with the excess of antimony were prepared by molecular beam deposition in vacuum on a SiO2(100 nm)/Si(001) substrate at the temperature of 200oC, followed by annealing in vacuum in the range of 300оС - 700оС. In the deposited films the polycrystalline untextured CoSb3 and Sb phases were observed. Thermal stability of crystalline CoSb3.6 (30 nm) and CoSb4.2 (30 nm) films keeps up to  300°C. At annealing of nanoscaled CoSbx(30 nm) (3.6 ≤ x ≤ 4.2) films at temperatures above 300°C - 400°C sublimation of not only excessive Sb but also of Sb from antimonide CoSb3 occurs. At annealing of the films, antimony first diffuses to the grain boundaries from where it then sublimates. The level of stress varies. After deposition in the films it is observed a slight level of tensile stress 1 GPa, which raises after thermal annealing up to  5 GPa and is accompanied by appearing of pores and cracks in the film.

V.V I.4
17:30
Authors : O. V. Fihurna, I.O. Kruglov, K.V. Slipchenko, S.I. Sidorenko, Iu.N.Makogon
Affiliations : Kyiv Polytechnic Institute, National Technical University of Ukraine, 03056, Prospect Peremogy 37, Kyiv, Ukraine

Resume : Effect of Ag(7,5mn) layer location (as top, underlayer and intermediate layer) on the phase and structural transformation in Fe50Pt50 thin films on SiO2(100 nm)/Si(001) substrates were investigated by methods of XRD, AFM. Magnetic properties were measured by SQUID. All as-deposited samples show disordered A1(FePt) structure. The location of additional Ag layer affects the initial stress/strain state in FePt layer, and thus the temperature of A1 in L10 phase transformation. In comparison with Ag top and underlayer films the films with intermediate Ag layer have a more high level of compressive stresses that lead to a decrease of ordering temperature of the L10 phase formation by 100°С up to 700°C. In the film with Ag top and underlayer L10 phase was formed after annealing at more high temperature above 800°С. Ag diffuses along boundary grains and decreases exchanging coupling interaction between FePt grains that lead to increasing of coercivity to big values of 20 kOe in films with Ag underlayer. The authors would like to thank Prof. M. Albrecht and Dr. G. Beddies and workers from Chemnitz University of Technology (Germany) for sample preparation, assistance in conduction of investigations and discussion of results.

V.V I.5
17:30
Authors : T.I. Verbytska, M. Yu. Verbytska, A. I. Falovska, S.I. Sidorenko, Iu.N.Makogon
Affiliations : Kyiv Polytechnic Institute, National Technical University of Ukraine, 03056, Prospect Peremogy 37, Kyiv, Ukraine

Resume : Influence of Au intermediate layer in nanoscaled Fe50Pt50(15nm)/Au(x nm)/Fe50Pt50(15nm) film composition (where х = 0;7.5;15;20; 30 nm) on SiO2(100 nm)/Si(001) substrates on the transformation of disordered А1(FePt) phase into ordered L10 (FePt) phase at annealing in vacuum was investigated by methods of XRD; AFM and MFM. Magnetic properties were measured by SQUID and magneto-optic Kerra effect method. It was established that during deposition the А1(FePt) phase forms in all films. Au interlayer thickness effects on initial stress/strain state in FePt layer and thus on temperature of А1 L10 phase transformation. As-deposited films with Au of 7.5 and 30 nm have a high level of compressive stresses in comparison with film without Au layer that lead to decreasing of ordering temperature of L10 phase. The formation of L10 phase in film with 7.5 nm-thick Au occurs during annealing at 650°С. Increase of Au thickness up to 20 and 30 nm decreases the ordering temperature up tо 600°С. Coercivity of film with 7.5 and 30 nm Au interlayers after annealing at 900°С increases up to 16.55 to 27.3 kOe, correspondingly. Au diffuses along boundary grains and decreases exchanging coupling interaction between FePt grains that lead to increasing of coercivity. The authors would like to thank Prof. M. Albrecht and Dr. G. Beddies and workers from Chemnitz University of Technology (Germany) for sample preparation, assistance in conduction of investigations and discussion of results.

V.V I.6
17:30
Authors : Sare AKGÖZ, Elif PEKSU, Hakan KARAAĞAÇ
Affiliations : İstanbul Technical University; İstanbul Technical University; İstanbul Technical University

Resume : CuIn0.9Ga0.1Se2 (CIGS) thin films deposited onto corning glass substrates using thermal evaporation technique. The structure and composition of the films were investigated using X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDXA), respectively. XRD analysis showed that there was a monophase of CuIn0.7Ga0.3Se2 phase in the structure with (1 1 2) preferred orientation without any secondary phases. EDXA analysis revealed that deposited thin films were not stoichiometric, understood from the atomic percentages of constituent elements in the composition. Surface morphologies of films were studied using atomic force microscopy (AFM), which revealed that as-deposited and annealed films at 150oC-450oC have agglomerations in different sizes distributed over their surfaces. These agglomerations were attributed to the segregation of constituent elements and structural modification following the post-annealing process. The optical properties of CuIn0.9Ga0.1Se2 thin films were determined by transmittance and reflection measurements. The band gap values were calculated as 1.14 and 1.25 eV for as-deposited and film annealed at 450oC, which was in a good agreement with previously reported values for the same compound in the literature. Photo-electrical measurements under different illumination intensities were carried out to understand the response of the deposited thin films under light and measure the room temperature resistivities. Results showed that the films were highly sensitive to the light and resistivities of as-grown and film annealed at 250oC were 6.1x10-3 and 6.5x105 Ωcm, respectively.

V.V I.7
17:30
Authors : A.Kosik1*, W. Święszkowski1
Affiliations : The Faculty of Materials Science and Engineering, Warsaw University of Technology

Resume : Scaffolds for tissue reconstruction and regeneration must have appropriate structural and functional properties. Recently, hydrogels have become attractive materials applied to the repair different tissues and organs. Biodegradable and biocompatible hydrogels are crosslinked networks of hydrophilic polymers that have the capacity to retain large volumes of water. A particular advantage of high water content is easier transport of important nutrients inside the structure of the scaffold. Moreover, the hydrogels possess mechanical properties very similar to the soft tissues. One group of the hydrogels that have shown excellent potential in variety of biomedical applications are alginates. Traditionally, alginate hydrogels have been crosslinked via printing alginate solution into CACl2 bath or mixing them before printing. In this work, we proposed to use a coaxial dispensing system. This system make possible to deposit a solid filament by the extruding at the same time the polymeric and the crosslinking solution. The special design coaxial needle included the inner core and outer shell was used to fabricate scaffolds with controllable speed of crosslinking. We use poly-L-lysine (PLL) to modify structure of alginate. The adhesion is interpreted simple as the interaction between the polyanionic cell surface and the polycationic layer of absorbed polylysine. In the study, three stage crosslinking: physical, electrostatical and chemical were used.

V.V I.8
17:30
Authors : Katarzyna Grochowska1, Katarzyna Siuzdak1, Jakub Karczewski2, Mariusz Szkoda3, Gerard Śliwiński1
Affiliations : 1Centre for Plasma and Laser Engineering, The Szewalski Institute, Polish Academy of Sciences, 14 Fiszera St., 80-231 Gdańsk, Poland; 2Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, Narutowicza 11/12 St., 80-233 Gdańsk, Poland; 3Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12 St., 80-233 Gdańsk, Poland

Resume : Noble metal nanostructures are the object of great interest due to their unique optical and electronic properties exploited in nanotechnology, medicine, biochemistry and surface enhanced spectroscopies. In this work the geometry and the optical and spectroscopic properties of the Au nanoparticle (NP) structures obtained by dewetting are investigated in dependence on their preparation conditions. Structures are produced from thin Au films (5-20 nm) sputtered onto the ITO, FTO and glass substrates. The dewetting is performed by thermal treatment in ambient air. SEM inspection of the structures reveal breakup of the Au films into NPs of nearly spherical shape. The NP size does not exceed 100 nm and can be tuned by changing the initial thickness of the Au layer and the substrate material, too. In the absorbance spectra the broad peaks centered around 550-610 nm are ascribed to resonant absorption of the surface plasmons and the nonradiative and radiative contributions to broadening of the absorption profile are estimated. As observed, for large particles the radiative component is dominant while the nonradiative one is small and remains approximately constant for all examined samples. The large signal values observed in Raman spectra confirm that the investigated materials can serve as active substrates for surface enhanced spectroscopy. KG and KS acknowledge the National Science Centre of Poland for financial support via grants 2012/07/N/ST5/02139 and 2012/07/D/ST5/02269.

V.V I.9
17:30
Authors : N.D. SCARISOREANU (1), A.I. BERCEA (1), V. ION (1), A. ANDREI (1), F. CRACIUN (2), R. BIRJEGA (1) and M. DINESCU (1)
Affiliations : 1) National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor St, RO-077125, Magurele, Romania; 2)CNR-ISC, Istituto Dei Sistemi Complessi, Via del Fosso del Cavaliere 100, I-00133 Rome, Italy

Resume : Lead free (Ba1−xCax)(ZryTi1−y)O3 (BCZT) ceramic materials with high value of dielectric constant and longitudinal piezoelectric coefficient d33 around 650 pC/N, were studied intensively in last years for replacing piezoelectric and ferroelectric materials containing toxic elements. Different properties can be obtained ranging from normal ferroelectrics up to relaxor ferroelectrics by varying the amount of A-site (Ca2+) and B-site (Ti4+) isovalent substitutions in BCTZ system. In our work the epitaxial strained thin films of BCTZ with composition around morphotropic phase boundary (MPB) were deposited using pulsed laser deposition method (PLD) on SrTiO3 and SrLaAlO3 substrates. The properties of the BCTZ thin films obtained by PLD tehnique were investigated with various tehnique such as XRD, AFM and H-RTEM tehniques for morfology and cristalinity; Spectroscopic Ellipsometry (SE) for optical properties; PFM and dielectric spectroscopy for dielectric and piezoelectric properties. Pure perovskite phase have been obtained with high refractive index and low extinction coefficient for (Ba1-xCax)(ZryTi1-y)O3 thin films epitaxially grown on SrTiO3(001). Very high in-plane dielectric permittivity (e’~3000) and low dielectric loss (tand<0.01) values have been obtained on (Ba1-xCax)(ZryTi1-y)O3 strained thin films grown on SrTiO3(001) by pulsed laser deposition.

V.V I.10
17:30
Authors : N.D. Scarisoreanu (1), V. Ion (1,2), A. Andrei (1), S. Antohe (2), R. Birjega (1), A.I. Bercea (1,2) and M. Dinescu (1)
Affiliations : 1) National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor St, RO-077125, Magurele, Romania; 2) University of Bucharest, Faculty of Physics, 405 Atomistilor St, RO-077125, Magurele, Romania

Resume : In last period, the perovskitic materials with small band-gap have become very attractive for photovoltaic and photocatalytic applications. In our work, we report the properties of Y-doped BFO thin films deposited by pulsed laser deposition method (PLD) on different substrates. The purpose of this study was to obtain thin films of Y-doped with values of the band gap smaller that for pure BFO proving that this material can be a candidate for photovoltaic applications. A parametric study on the influence of nature of substrate, temperature during deposition and gas pressure on the properties of the BFO thin layer was carried out. Targets used in our experiments were ceramic targets with different concentration of doping element (1.5%Y, 5%Y and 10% Y). Crystalline properties and topography of surface of thin films were studied using X-ray diffraction, atomic force microscopy (AFM). The optical properties were determined by spectroscopic ellipsometry (SE) and the values of band gap (Eg) where determined from Tauc plot. We have obtained very high in-plane dielectric permittivity (e?~2500) and low dielectric loss (tand< 0.01) on Y-doped BiFeO3 films epitaxially grown on SrTiO3(001) by pulsed laser deposition; the value of band gap is decreased from 2.71 eV for BFO to 2.1eV for 5% Y-doped BiFeO3 thin film.

V.V I.11
17:30
Authors : C. N. Mihailescu1, 2, R. Negrea3, C. Ghica3, C. R. Luculescu and J. Giapintzakis1*
Affiliations : 1Nanotechnology Research Center and Department of Mechanical and Manufacturing Engineering, University of Cyprus, 75 Kallipoleos Avenue,PO Box 20537, 1678 Nicosia, Cyprus 2National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-36, 077125 Magurele, Romania 3National Institute of Materials Physics, RO-077125 Magurele, Romania

Resume : The further miniaturization in semiconductor technology has led to nanoscale chip feature sizes and significant increases in on-chip power dissipation as well as heat flux at the silicon level [1]. New materials and process improvements are required to minimize thermal resistance. Recently, the 1D half-spin Heisenberg antiferromagnet La5Ca9Cu24O41 has attracted considerable attention due to his highly anisotropic magnon-mediated thermal conductivity [2]. Since the heat is conducted primarily along one crystal axis, a solution to efficiently channel away parasitic heat such as that generated in integrated semiconductor circuits may come from using a heat conductive layer of such material. However, in order to exploit this anisotropic heat transport property, there are several important requirements which need to be considered: i) to obtain La5Ca9Cu24O41 in a stoichiometric thin film form and ii) the films have to be epitaxially grown. Recent literature on the growth of complex oxide thin films proposes the lattice mismatch induced strain as another way to obtain an epitaxial growth. It has also been suggested that there is a strong correlation between the interfacial strain, the lattice mismatch and the film thickness, i.e., the thinner the film the larger the interfacial strain/stress. In this work we have investigated the effect of the interfacial strain on the growth of La5Ca9Cu24O41 thin films. Films with various thicknesses have been grown on SrTiO3 substrates by Pulsed Laser Deposition (PLD). The films composition has determined by energy dispersive spectroscopy (EDX). Their crystal structure has been studied by high resolution X-ray diffraction (HR-XRD) and high resolution transmission electron microscopy (HR-TEM), while their strain nature has been evaluated from HR-XRD and Geometrical Phase Analysis (GPA) measurements. [1] C. Bachmann and A. Bar-Cohen, 11th Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, IEEE, p. 238, Orlando (2008). [2] C. Hess, C. Baumann, U. Ammerahl, B. Buchner, F. Heidrich-Meisner, W. Brenig, and A. Revcolevschi, Phys. Rev. B, 64, 184305, (2001).

V.V I.12
17:30
Authors : G. Socol1, D. Craciun1, G. Dorcioman1, N. Stefan1, V. Craciun1, D. Cristea2, L. Floroioan3, M. Badea4, D. Pantelica5, P. Ionescu5
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, Măgurele, Romania; 2Materials Science Department, Transilvania University, Brasov, Romania; 3 Fac Elect Engn & Comp Sci,Transilvania Univ Brasov, Brasov, Romania 4Faculty of Medicine, Transilvania University, Brasov, Romania; 5Horia Hulubei National Institute for Physics and Nuclear Engineering, Măgurele, Romania

Resume : Transition metal carbides and nitrides have been extensively investigated as hard and protective coatings since they possess both excellent ceramic and metallic properties. Such properties are very useful for many applications where there is a combination of mechanical wear under corrosive liquids. The Pulsed Laser Deposition (PLD) is the best technique to grow thin carbide and nitride films to investigate their properties. It has been observed that PLD grown films are under rather high compressive stress values. We deposited ZrC, ZrN, TiN and TiC thin films using the PLD technique under various conditions on Ti, Si and stainless steel substrates. The mechanical properties of the films were characterized by nanoindentation, scratch and wear tests. The structural properties were obtained from grazing incidence X-ray diffraction and X-ray reflectivity investigations. The chemical composition was measured by Rutherford backscattering spectrometry. Measurements involving corrosion and electrochemical impedance spectroscopy studies were carried out in physiological solutions to investigate the chemical stability of the PLD grown films. These investigations helped us understanding the effect of the stress on the mechanical and corrosion resistance of PLD grown films.

V.V I.13
17:30
Authors : G. Dorcioman1, G. Socol1, D. Craciun1, N. Stefan1, S. Behdad2, B. Boesl2, D. Simeone3, V. Craciun1
Affiliations : 1Laser Department, National Institute for Laser, Plasma, and Radiation Physics, Bucharest-Magurele, 077125, Romania; 2Florida Int Univ, Dept Mech & Mat Engn, Miami, FL 33174 USA; 3DMN/SRMA-LA2M, LRC CARMEN CEA Saclay, France

Resume : We report here the effects induced in transition metal carbo-nitrides thin films by Ar ion irradiation. The aim is to evaluate the ion irradiation behavior and to determine the upper limit tolerance doses below which mechanical properties of these hard coatings are not catastrophically affected and, by this way, could extend the service life of a materials used in nuclear reactor, for example. Carbo-nitride Zr thin films were grown by combinatorial-pulsed laser deposition (C-PLD) from two different targets, ZrN and ZrC respectively. The experiments have been performed using a KrF excimer laser (λ=248 nm, pulse duration τ = 25 ns, 40 Hz repetition rate), under CH4 or N2 atmosphere (2x10-5 mbar), on Si (100) substrates, heated and kept at 500ºC. Each target has been irradiated with 30000 subsequent laser pulses. The obtained thin films are investigated from structural, morphological, compositional, and mechanical point of view. After deposition, the films were irradiated by 800 keV Ar ions. The changes of the structure, stoichiometry and properties were investigated and compared to results obtained for ZrC and ZrN films.

V.V I.14
17:30
Authors : Mourad Azibi, Nadia Saoula
Affiliations : Centre de développement des technologies avancées Cité 20 août 1956 Baba Hassen, Alger, Algérie

Resume : The electronic, elastic constants and optical properties of TiN and TiC have been investigated using first principle pseudopotential method within generalized gradient approximation (GGA) proposed by Perdew–Burke–Ernzerhof (PBE). The calculated volume and bulk modulus are in good agreement with previous experimental and computational results. The higher density of states and expanded energy bands around the fermi level is obtained. Calculated elastic constants satisfying the Born stability criteria suggest that TiN and TiC are mechanically stable. The dielectric constant is identified with respect to electronic band structure and is utilized to derive the other optical properties like refractive index, reflectivity, absorption and conductivity. Our investigated results are in good accord with the existing theoretical and experimental results. Keywords: DFT, generalized gradient approximation, TiN, TiC.

V.V I.15
17:30
Authors : Mourad Azibi, Nadia Saoula
Affiliations : Centre de Développement des Technologies Avancées, Cité 20 août 1956 Baba Hassen, Alger, Algérie

Resume : First-principles calculations of the crystal structures, bulk moduli, and relative stabilities of TiO2 rutile and anatase were successfully calculated and simulated by a plane wave pseudopotential The minimum total energy of the structure is achieved by relaxing automatically the internal coordinates using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm. The calculated unit cell data agree to within 2% of the corresponding experimental determination and calculated bulk moduli are within 10% of the most reliable experimental results. Rutile TiO2 (100) and (110) slabs are constructed before the calculation by cleaving a bulk TiO2 after geometry optimization. A vacuum region with the thickness of 15 Å is included in the supercell to prevent the interaction between the slab and its periodic images. The calculated results of structural relaxation and surface energy for TiO2 (110) and (100) slab indicate that a 10 and 12 layers slab, respectively, were found to be a good surface model. The surface energy of TiO2 (100) and (110) are calculated to be 0.72 and 0.51 J/m2, respectively. Our investigated results are in good accord with the existing theoretical results. Other properties like band structure and raman spectrum were also investigated.

V.V I.16
Start atSubject View AllNum.
 
Session 5 : chair Paolo Ossi
09:00
Authors : Chantal Boulmer-Leborgne1, Thibault Labbaye1, Eva Kovacevic1, Shahzad Hussain1, Soufyane Belhenini2, Abdellah Tougui2, Aurélien Canizares3, Mohamed-Ramzi Ammar3 , Patrick Simon3, Franck Dosseul4
Affiliations : 1-GREMI Université d’Orléans-CNRS 14 rue d’Issoudun 45064 Orléans cedex2 France 2-LMR 7 Avenue Marcel Dassault 37004 TOURS 3-CEMHTI 1D avenue de la Recherche Scientifique 45071 ORLEANS cedex 2 4-STMicroelectronics 16 Rue Pierre et Marie Curie, 37100 Tours

Resume : CNTs are a type of novel material attracting great attention due to their outstanding thermal, electrical, and mechanical properties. These properties make them a promising alternative to interconnect materials for electronic packaging applications. As the performance of semiconductor products increases, the technical challenges increase in areas of power delivery, heat removal, input/output density, and thermomechanical reliability. Down-scaling the traditional interconnects does not satisfy the requirements and the development, process, and design of interconnect materials are driven into entirely new directions. In the presented study the different growth kinetics of several kinds of catalyst/substrate couple are investigated by analyzing the CNT carpets at different times during the PECVD growth, by NEXAFS ex situ and Raman in situ for different experimental conditions. Electrical, thermal and mechanical properties are determined on CNT carpets and interconnect tests are achieved for industrial applications.

V.5.1
09:30
Authors : J.M. Macak (a), P. Knotek (b), H. Sopha (a), M. Krbal (a), J. Subrt (c), M. Klementova (c)
Affiliations : (a) Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice Nam. Cs. Legii 565, 530 02 Pardubice, Czech Republic; (b) Dep. of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice Studentska 573, 532 10 Pardubice, Czech Republic; (c) Institute of Inorganic Chemistry of AS CR, Husinec-Rez 1001, 25068 Rez, Czech Republic

Resume : Synthesis of highly-ordered nanostructures of valve metal oxides has recently attracted huge scientific and technological interest motivated by their possible use in many applications. The nanoporous Al2O3 – most established material of this group – has been prepared by anodic oxidation of Al under suitable electrochemical conditions into perfectly ordered, honeycomb-like porous structures (Masuda & Fukuda, Science, 1995). It is the TiO2 that has received the next highest attention motivated by its range of applications. Very significant research efforts have led to reproducible synthesis of self-organized TiO2 nanotube layers by means of anodic oxidation, during which the Ti substrate is converted into highly-ordered nanotubular layer in suitable electrolytes. Although advancements in the anodic synthesis of TiO2 nanotube layers have been presented over past years, the degree of ordering has not reached so far the level known from porous Al2O3. Numerous factors influence the ordering and the homogeneity of TiO2 nanotube layers. In the presentation, we aim to demonstrate considerably significant advancements in the ordering of anodic TiO2 nanotubes and its implications. We will show how to obtain via tailored anodization protocols a very decent degree of uniformity and homogeneity of the nanotube layers. Moreover, based on SEM, EBSD and TEM measurements, we will demonstrate how the Ti grain structure influences the lateral uniformity of the nanotube layers.

V.5.2
09:50
Authors : Kunmo Chu, Sangeui Lee, Chang seung Lee
Affiliations : Samsung Advanced Institute of Technology

Resume : Zero temperature coefficient of resistance (TCR) is essential for the precise control of temperature in heating element and sensor applications. Many studies have focused on developing zero-TCR systems with inorganic compound; however, very few have dealt with developing zero-TCR systems with polymeric materials. Composite systems with a polymer matrix and a conducting filler show either negative (NTC) or positive temperature coefficient (PTC) of resistance, depending on several factors, e.g., the polymer nature and the filler shape. In this study, we have demonstrated a new hybrid bi-layer zero-TCR composite consisting of stacked layers showing NTC and PTC of resistance. The bi-layer composites consisted of a carbon nanotube (CNT)-based layer having a NTC of resistance and a carbon black (CB)-based layer having a PTC of resistance which was in direct contact with electrodes to stabilize the electrical resistance change during electric Joule heating. The composite showed nearly constant resistance values with less than 2 % deviation of the normalized resistance until 200 °C. The CB layer worked both as a buffer and as a distributor layer against the current flow from an applied voltage. This behavior, which was confirmed both experimentally and theoretically, has been rarely reported for polymer-based composite systems.

V.5.3
10:10
Authors : Marcio Partichelli*, Jaison R. da Costa*, Ricardo A.S. Zanon*, Julio M. Pureza*, Monica M. Lacerda#
Affiliations : * Universidade do Estado de Santa Catarina, Brazil; # Universidade Federal do Rio de Janeiro, Brazil

Resume : Hydrogenated Amorphous Carbon (a-C:H) films were deposited by plasma enhanced chemical vapor deposition (PECVD) at room temperature using a mixture of argon (30%) and acetylene (C2H2) as atoms precursor. The samples were exposed to an ultraviolet lamp, to alpha particles from americium and to gamma radiation. They were analyzed as a function of the deposition pressure that ranged from 7 Pa up to 213 Pa with a fixed 600V tension, by Raman spectroscopy with 1064 nm excitation wavelength, Scanning Electron Microscopy, Confocal Microscopy and by measuring their contact angle between the surface and deionized water droplets. Raman spectroscopy show typical D and G bands, as observed in carbonaceous materials and the results were used to characterize the microstructure of the films [1,2]. ID/IG intensity ratio results indicated that films deposed at higher pressures are polymeric while low pressure films are graphitic [3,4]. The contact angle measures show a change in the wetting character of the samples. At lower pressures, they are hydrophilic and the contact angle increases with the pressure, reaching a superhydrophobic state at 213 Pa. The exposition to radiation reduces the contact angle, indicating changes in the microstructure of the films as verified by the analysis of the half width (FWHM) and ID/IG ratio of the bands. [1] Ferrari, A.C.; Robertson, J. Interpretation of Raman spectra of disordered and amorphous carbon. Phys. Rev. B 61, 14095-14107, 2000. [2] Robertson, J. Diamond-like amorphous Carbon, Mater. Sci. Eng., R Rep. 37, 129-281, 2002. [3] Antunes, E.F.; Lobo, A.O.; Corat, E.J.; Trava-Airoldi, V.J.; Martin, A.A.; Veríssimo, C. Comparative study of first- and second-order Raman spectra of MWCNT at visible and infrared laser excitation. Carbon, 44, 2202–2211, 2006. [4] Paul K.C.; Liuhe L.; Characterization of amorphous and nanocrystalline carbon films. Mat. Chem. and Phys., 96, 253–277, 2006.

V.5.4
10:30 Coffee break    
 
Session 6 : chair Sergio D'Addato
11:00
Authors : L. Spallino, L. Vaccaro, M. Cannas, F. M. Gelardi
Affiliations : Dipartimento di Fisica e Chimica, Universita degli Studi di Palermo (Italy)

Resume : The large variety of defects arising from the constraints imposed by the nanoscale is at the origin of the huge emissivity observed in SiO2 nanoparticles. Generally, broad and structureless emission bands characterize the UV-Visible spectral region, reflecting the amorphous matrix in which the defects are embedded. An exception is observed in a vacuum and consists of a structured photoluminescence, between 3.0 eV and 3.5 eV, whose sharp spectral features resemble those of a single molecule. This emission is due to the coupling of an electronic transition with two localized modes of frequency 1370 cm-1 and 360 cm-1. Its quenching in air points out that the defects are allocated on the surface of the nanoparticles and strongly interact with the molecular species of the environment. The pronounced sensitivity to the atmosphere, in combination with the advantageous spectral features, is promising for the use of SiO2 nanoparticles as luminescent sensors of small molecules. To this aim, the understanding of the fundamental mechanisms of the quenching is mandatory. By using time resolved photoluminescence technique, we have carried out a detailed investigation of the effects on the intensity and lifetime of the structured emission on varying the interaction with specific molecular species (O2, N2). The findings indicate that the quenching mechanisms is controlled by collisional- and reaction-limited processes thus evidencing the sensing property of SiO2 nanoparticles.

V.6.1
11:30
Authors : V. Braza-Blanco1, D. F. Reyes1, T. Ben1, A. D. Utrilla2, J. M. Ulloa2, D. Gonzalez1.
Affiliations : 1 Departamento de Ciencia de los Materiales e IM y QI, Universidad de Cádiz, 11510 Puerto Real (Cádiz), Spain; 2 Institute for Systems based on Optoelectronics and Microtechnology (ISOM), Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain

Resume : Nowadays, depositing specific capping layers (CLs) on InAs quantum dots (QDs) consisting of GaAs-based alloys is a promising way to tailor the optical properties of devices for telecommunication and solar cell applications. However, the nature and the growth conditions of such CLs are critical parameters determining the final structural and optical properties of the QDs. In this work, we analyze statistically, by transmission electron microscopy (TEM) and atomic force microscopy (AFM) techniques, the effect of a variety of GaAs(Sb)(N) CLs on QD parameters such as height, aspect ratio and volume. Firstly, AFM and TEM revealed that the buried QDs, compared to the uncapped ones and independently of the capping material, always evolve into a dome shape undergoing an asymmetric decomposition with a considerable reduction of the base diameters but not of their heights. The CL features such as composition and growth rate, affect the amount of the QD volume reduction but not the average aspect ratio, which is preserved. Remarkably, the analysis of indicative parameters such as the radius of curvature, among others, reveals that the QD erosion in GaAs-based CLs follows a unique trend independently of the different decomposition mechanisms involved, whereby the addition of Sb and/or N only strengthen or weaken this process in a relative small percentage.

V.6.2
11:50
Authors : Yuanpeng Zhang1, Ali Karatutlu1, 2, Osman Ersoy1, Dima Bolmatov1, 3, Kostya Trachenko1, Andrei Sapelkin1
Affiliations : 1. Queen Mary, University of London; 2. Hursa Orhangazi University; 3. Cornell University

Resume : We used x-ray absorption spectroscopy (XAS) and optically-detected XAS (ODXAS) to explore the structural origins of light emission in small (~4 nm) oxygen-terminated and oxygen-free Ge quantum dots (QDs) prepared by colloidal synthesis. Taking advantage of EXAFS capability to provide site-sensitive structural information in low dimensional systems, we have been able to recover information about local structure of samples. Furthermore, we showed the high sensitivity of x-ray absorption near edge structure (XANES, obtained from XAS data) to the local symmetry (owing to the long photoelectron mean free path) could indeed provide more information about local symmetry that could not be observed by EXAFS directly. Moreover, using ODXAS technique we obtained structural data directly from the light emission signals and thus have been able to link directly light emission with the atomic-level structure. It was found that in oxygen-terminated Ge QDs, it’s the oxide-rich regions that are responsible for the light emission. For the hydrogen-terminated sample, we found a diamond-type Ge crystalline core and a sub-nanometer amorphous surface layer based on comprehensive analysis of EXAFS/XANES data. And ODXAS signal shows it is the surface amorphous layer that plays the key role in the light emission of our Ge QDs.

V.6.3
12:10
Authors : Yang Han, Ming Hu
Affiliations : Institute of Mineral Engineering, Division of Materials Science and Engineering, Faculty of Georesources and Materials Engineering, RWTH Aachen University, 52064 Aachen, Germany; Aachen Institute for Advanced Study in Computational Engineering Science (AICES), RWTH Aachen University, 52062 Aachen, Germany

Resume : Well-ordered and freestanding bilayer silica  a new member of two-dimensional (2D) family  have great advantage in versatile modern technologies and applications that range from insulating layers in integrated circuits to supports for sensors and catalysts, as well as protective films against corrosion etc. Motivated by this, a lot of work on mechanical properties has been done, while thermal transport properties received less attention. By performing DFT calculation a new ground state of bilayer h-silica was found. Remarkably, it has negative Poisson’s ratio at small strains, while the Poisson’s ratio has negative to positive transition at some critical strain. The underlying mechanism of the negative Poisson’s ratio stems from the intrinsic rotational angle of SiO3 triangular pyramids. Moreover, we studied the thermal conductivity of O-silica, another type of silica layer, under biaxial strain using DFT based Boltzmann transport equation. An unexpected drastic decrease in lattice thermal conductivity of O-silica with tensile strain was observed, in contrast to the behavior of graphene, a representative of 2D materials. The relationship between the unusual strain dependent thermal conductivity and the silica layer structure is further studied. The current research adds scientific value to the fundamentals of 2D materials and we expect that it will arouse great interest of experimentalists to carry forward the application of silica as new electronic materials.

V.6.4
12:30 Lunch break    
 
Session 7 : chair Chantal Leborgne
14:00
Authors : A. Higo, C. Thomas, T. Kiba, J. Takayama, C.Y. Lee, Y. Tamura, ,I. Yamashita, M. Sugiyama, Y. Nakano, A. Murayama, S. Samukawa,
Affiliations : WPI-AIMR, Tohoku Univ.; IFS, Tohoku Univ.; Hokkaido Univ.; Hokkaido Univ.; IFS, Tohoku Univ.; IFS, Tohoku Univ.; NAST; the Univ. of Tokyo; the Univ. of Tokyo; Hokkaido Univ.; IFS, Tohoku Univ.;

Resume : Top-down fabricated quantum nanodisks (QNDs) lasers are one of the most promising light sources because of their theoretically improved performances compared to quantum well and bulk lasers. The bio-template is used to create a high density etching mask and low-damage etching is performed by using neutral beam (NB). The bio-template is realized by cage-shaped proteins called ferritins of 12 nm outside diameter with a 7 nm iron oxide core, and functionalized with poly-ethylene glycol (PEG) to control the gap between cores to avoid any QNDs coupling after fabrication. After removing the protein shell by oxygen annealing, a high-density nano-pattern of cores is realized as etching mask. The NB etching system consists of an inductively coupled plasma chamber separated from the process chamber by a carbon electrode with a high aspect-ratio aperture array, therefore, the charged particles are efficiently neutralized and the UV photons from plasma almost completely screened. InGaAs/GaAs multiple quantum wells were grown by metalorganic vapor phase epitaxy (MOVPE), with a few nanometers thick InGaAs cap layer. Ferritins were self-assembled by spin-coater. After removing protein shell by oxygen annealing in vacuum, a hydrogen radical treatment was performed to remove the oxide layer. Etching was then realized by pure chlorine NB. Regrowth of GaAs barrier was done by MOVPE. Finally, InGaAs QND based light emitting diode were realized.

V.7.1
14:30
Authors : A. Carretero-Genevrier 1, Judith Or?-Sol? 2, Jaume G?zquez 2, Teresa Puig 2, Xavier Obradors2, Cl?ment Sanchez3, Etienne Ferain4, Juan Rodr?guez-Carvajal5, Narc?s Mestres2
Affiliations : 1 INL, Institut des Nanotechnologies de Lyon, France2 2 Institut de Ci?ncia de Materials de Barcelona ICMAB, Consejo Superior de Investigaciones Cient?ficas CSIC, Campus UAB 08193 Bellaterra, Catalonia, Spain 3 UPMC-Coll?ge de France-CNRS 7574. Coll?ge de France, 11 place Marcelin Berthelot, 75231 Paris 4Universit? Catholique de Louvain, Croix du Sud 1,1348 Louvain-la-Neuve, Belgium, and it4ip s.a., rue J. Bordet (Z.I. C), 7180 Seneffe, Belgium 5 Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France

Resume : Selective synthesis for integrated nanomaterials with controllable morphology and composition represents an emerging research area in nanoscience and nanotechnology because the intrinsic properties behind nanostructures are generally phase-, shape-, and size- dependent. In this direction the present work shows the capabilities of nanoporous polymeric template systems directly supported on different substrates for the confined growth of epitaxial ferromagnetic complex oxides nanostructures. In particular, we describe the versatility and potentiality of sol-gel precursor solutions combined with track-etched polymers to synthesize i) vertical polycrystalline La0.7Sr0.3MnO3 nanorods on top of single crystal perovskites [1,2], ii) single crystalline manganese based octahedral molecular sieves (OMS) nanowires on silicon substrates [3-5], and iii) the epitaxial directional growth of single crystal OMS nanowires when grown on top of fluorite-type substrates [6]. The influence of the distinct growth parameters on the nanostructural evolution of the resulting nanostructures and their magnetic properties are studied in detail. Therefore, we demonstrate that the combination of soft-chemistry and epitaxial growth opens new opportunities for the effective integration of novel technological functional complex oxides nanomaterials on different substrates. [1] A. Carretero-Genevrier et al. Chem.Soc.Rev., 43, 2042-2054 (2014) [2] A. Carretero-Genevrier et al. Adv.Funct.Mater., 20, 892-897. (2010). [3] A. Carretero-Genevrier et al. Chem.Mater., 26 (2), 1019?1028 (2014) [4] A. Carretero-Genevrier et al. JACS., 133 (11), 4053?4061 (2011) [5] J. Gazquez et al. M&M., 20 (03) 760-766 (2014) [6] A. Carretero-Genevrier et al. Chem.Comm., 48, 6223-6225 (2012)

V.7.2
14:50
Authors : * Zied Rouissi * Dieter Schmeißer ** Massimo Tallarida
Affiliations : *Department of Applied Physics and Sensors, Brandenburg University of Technology, Konrad Wachsmann Allee 17, 03046 Cottbus, Germany **ALBA-CELLS, Carretera, BP 1413, Km. 3.3, E-08290 Cerdanyola, Barcelona, Spain

Resume : The role of the structural properties of the substrates related to the thin film growth by atomic layer deposition (ALD) is addressed in this study. We argue that the detailed knowledge of precursor-substrate reactions is essential for an understanding of the ALD deposition process and its optimization. In this context in the present work scanning tunnelling microscopy (STM) is used to investigate the initial processes of the ALD process on non-planar substrates. Here, we report on results obtained on a stepped Si(111) surface. It is prepared using a vicinal Si(111) substrate and wet chemical etching in 40% NH4F solution to obtain steps in the [11-2] direction. In our in-situ study we followed the ALD growth of HfO2 by using Tetrakis-(dimethylamido)-hafnium(IV) (TDMAH) and H2O as oxidation source [1-3] . We follow for every half cycle the distribution of the nucleation sites and, in particular, focus on the presence of the step edges. We also study the influence of the substrate temperature by studying the growth within the ALD window at different deposition temperatures starting from room temperature up to 400°C. Based on our data we are able to correlate the structural changes on the vicinal surfaces during ALD with theoretical models [4]. [1] M. Tallarida et al., Semicond. Sci. Technol. 27, 074010 (2012) [2] K. Kolanek et al.,Thin Solid Films 518, 4688 (2010) [3] K. Kolanek et al., J. Vac. Sci. Technol. A 31, 01A104 (2013) [4]L. Riikka et al., J. Appl. Phys.96,7686 (2004)

V.7.3
15:10
Authors : Penkala Bartosz, Paulus Werner, Kaper Helena
Affiliations : University of Montpellier, Institut Charles Gerhardt, UMR 5253, C2M, 5 Place Eugene Bataillon, F-34095, Montpellier, France Ceramic Synthesis and Functionalization Laboratory, Saint-Gobain CREE, 550 av. Alphonse Jauffret, F-84306, Cavaillon, France; University of Montpellier, Institut Charles Gerhardt, UMR 5253, C2M, 5 Place Eugene Bataillon, F-34095, Montpellier, France; Ceramic Synthesis and Functionalization Laboratory, Saint-Gobain CREE, 550 av. Alphonse Jauffret, F-84306, Cavaillon, France;

Resume : Investigation of CaFeO2.5 with characteristic Brownmillerite structure by inelastic neutron scattering combined with ab inito molecular dynamical calculation proved existence of low energy lattice modes, which trigger and amplify oxygen mobility in solids [1, 2]. Structural instabilities in Brownmillerite-type materials, which promote migration of oxygen ions, where at the origin for designing novel CaFeO2.5 catalysts with structural disorder controlled by the preparation technique. Using polycarbonates as surfactants, nano-CaFeO2.5 could be prepared with a controlled amount of extended defects i.e. anti phase boundaries. This is equivalent to the loss of the 3D ordering of (FeO4) ∞ tetrahedral chains, causing a reduction of oxygen mobility activation energy [3]. The catalytic oxidation of CO is enhanced for samples with a total loss of the 3D ordering of (FeO4) ∞ tetrahedral chains. Projecting the influence of lattice dynamics for oxygen mobility activated at already ambient temperature, we investigated modified CeO2-δ, to correlate the low temperature catalytic activity of ceria based compounds commercialized by Saint-Gobain, with diffraction (X-ray and neutron) and spectroscopic methods as a function of temperature. Combining TGA, Raman spectroscopic experiments and Isotope Labeling Pulse Temperature Programed Oxidation Reaction (ILPOR), coupled with mass spectrometric analysis on 18O doped ceria, we explored here the oxygen uptake/release kinetics under operando conditions together with the catalytic activity related either to surface and/or quantitative lattice oxygen mobility and exchange. Specific changes in the lattice dynamics induced by 18/16O isotope exchange were analyzed by Raman spectroscopy, allowing to study selectively the temperature dependent onset of lattice oxygen mobility and exchange behavior. Compared to the traditional CO conversion under continuous gas flow conditions, here employed ILPTPOR technique importantly allows together with the 18O labelling, to simultaneously analyse important parameters to explore the mechanism of the catalytic reaction. References 1. W.Paulus, H. Schober, S. Eibl, M. Johnson, T. Berthier, O. Hernandez, M. Ceretti, M. Plazanet, K. Conder, C. Lamberti, J. Am. Chem. Soc., 130, (47), 16080-85, (2008). 2. S. Inoue, M. Kawai, N. Ichikawa, H. Kageyama, W. Paulus, Y. Shimakawa, Nature Chemistry, 2, 213-217, (2010). 3. K. Gupta, S. Singh, M. Ceretti, M. S. Ramachandra Rao, W. Paulus, Phys. Status Solidi A, (2013), 1-7.

V.7.4
15:30 Coffee break    
 
Session 8 : chair Akio Higo
16:00
Authors : Livia Giordano
Affiliations : Dipartimento di Scienza dei Materiali, Università Milano-Bicocca, Via Cozzi 55, I-20125, Milano, Italy and Electrochemistry and Energy Laboratory, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA

Resume : Epitaxial films can be grown nowadays with accurate control of quality and thickness. In the limit of ultrathin films, the influence of the film/support interface confers new properties to the combined material, which can be exploited in technological applications. Several effects are at play at the interface between the two materials, including interfacial bonding and lattice strain. Moreover, other effects such as interfacial charge transfers and changes in stoichiometry are possible, in particular in the case of reducible oxides. We will report the case of a FeO film on Pt(111). Due to the lattice mismatch the film presents a typical Moiré structure, which modulates the surface properties. At high oxygen pressure the film changes stoichiometry while maintaining the long-range order. The oxygen-rich film was probed to consist of the coexistence of FeO and FeO2 phases, where the unusual FeO2 stoichiometry is stabilized by a charge transfer from the substrate. The high catalytic activity of this film for CO oxidation has been rationalized by the presence of oxide/oxide and oxide/metal boundary sites [1,2]. We will also show how the combination of theoretical simulations and high-quality experimental data can provide insights on the details of the interface at the atomic level, as elucidated for the case of CeO2/Pt(111) [3]. [1] Giordano et al., ChemCatChem 6, 185 (2014). [2] Pan et al., submitted. [3] Luches et al., in preparation.

V.8.1
16:30
Authors : Maria Chiara Spadaro1-2, Sergio D Addato1-2, Francesco Benedetti1-2, Paola Luches1, Sergio Valeri1-2, Giovanni Bertoni3, Vincenzo Grillo3, Stefano Turchini4, Anna Maria Ferretti5, Elena Capetti5, Alessandro Ponti5
Affiliations : 1 CNR-NANO, via G. Campi 213/a, 41125 Modena, Italy; 2 Dipartimento FIM, Università di Modena e Reggio Emilia, via G. Campi 213/a, 41125 Modena, Italy; 3CNR-IMEM, Parco Area delle Scienze 37/A - 43100 Parma, Italy; 4 Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche (CNR), Via Fosso del Cavaliere 100, 00133 Roma, Italy; 5 Laboratorio di Nanotecnologie, Istituto di Scienze e Tecnologie Molecolari, Consiglio Nazionale delle Ricerche, via G. Fantoli 16/15, 20138 Milano (Italy)

Resume : A viable strategy to overcome the superparamagnetic limit in nanosized magnetic memory units is the exploitation of the exchange bias (EB) effect, [1] occurring at the interface between an Anti Ferromagnetic (AFM) and a Ferromagnetic (FM) medium. Research in this field is still in progress, trying to study and optimize every physical process affecting the EB. Recently we have studied in detail the EB in Ni@NiO core-shell nanoparticle films realized with physical synthesis methods [2], with particular interest in the effect of the AFM shell thickness. We have obtained this system in a controllable and reproducible way, in order to study separately the effect of the Ni NP size, shell thickness and core-shell interface. With this method we could demonstrate the possibility of tuning coercivity and exchange field by playing separately with the different parameters controlling the NP synthesis. Recently, we have extended our investigation on Ni@CoO NPs, by making use of SEM, XPS, HR- and S-TEM, SQUID and XMCD technique, to assess the influence of the different shell AFM anisotropy. The interplay of interface and bulk effects in EB could be explored systematically, demonstrating the viability of our method to obtain magnetic NPs with enhanced stability. Our results pave the way for a rational design and synthesis of NPs with desired magnetic properties. [1] V. Skumryev et al., Nature 423 (2003) 850; [2] S. D'Addato et al. Appl. Surf. Sci. 2014, 306, 2-6.

V.8.2
16:50
Authors : P. NAWROCKI 1*, M. WÓJCIK 1, E. JĘDRYKA 1, E. MENÉNDEZ 2, A. VANTOMME 2 and K. TEMST 2
Affiliations : 1 Institute of Physics, Polish Academy of Sciences, 02-668 Warszawa, Poland 2 Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium

Resume : O+ ion implantation has been recently introduced as a new and efficient method of inducing exchange bias effect (EB) in the whole volume of ferromagnetic Co thin layers (as opposed to surface oxidation) and tailoring magnetic properties of these materials. 59Co Nuclear Magnetic Resonance (NMR) has been used in order to obtain information about changes of structural and magnetic properties of polycrystalline MBE-grown Co thin films (30 nm) implanted with O+ ions. The films were grown on an Au buffer, capped with an Au overlayer and subsequently implanted with O+ ions (at 40 keV energy), with increasing fluence ranging from 3×10^16 to 35×10^16 ions/cm^2. NMR investigations shown that while the as-deposited sample consists of a mixture of fcc and hcp-Co phases and stacking faults, implanted samples exhibit different structural features. Although there is no allotropic fcc › hcp phase transformation, the metallic Co undergoes a significant loss of crystalline order. For high fluence implantation, traces of CoO can be envisaged from a new NMR line present at around 450 MHz. 59Co NMR restoring fields indicate a large increase of magnetic stiffness at 4.2 K due to exchange anisotropy introduced by the presence of antiferromagnetic CoO (i.e. EB). 59Co NMR studies from annealed (573 K) samples have shown radical structural changes indicating a migration of implanted oxygen from the inner part of the Co film due to thermal activation and probable re-crystallization process.

V.8.3
17:10
Authors : Andreas Kaidatzis, Christos Serletis, Dimitrios Niarchos
Affiliations : Institute of Nanoscience and Nanotechnology, NCSR Demokritos, Athens, Greece

Resume : We study Ta-doped W/CoFeB/MgO stacks for Spin-Orbit Torque Magnetic Random Access Memory (SOT-MRAM) applications [1]. A typical SOT-MRAM stack is composed of a Magnetic Tunnel Junction (MTJ), two ferromagnetic layers separated by an oxide, grown on top of a high spin-orbit coupling metal. Obtaining MTJs with perpendicular magnetic anisotropy (PMA) is of crucial importance for efficiently scaling-down the memory cells to sub-22-nm technology nodes. Sputter-deposited W-Ta-alloy/CoFeB/MgO and W/CoFeB/Ta/CoFeB/MgO half-MTJ stacks are studied for determining the appropriate parameters for obtaining PMA. It has been shown in the literature that although Ta/CoFeB/MgO may readily obtain PMA after annealing [2], this is not the case for W/CoFeB/MgO stacks [3], indicating that Ta plays a crucial role as a “PMA-enhancing” element. Our main focus is on the W-Ta-alloy composition, the thickness of the Ta inter-layer and the effect that it has on the CoFeB/Ta and Ta/CoFeB interfaces, and the effect of the MgO deposition pressure on the CoFeB/MgO interface. We find that the above-mentioned parameters have to be finely tuned for obtaining PMA and maximizing the magnetic anisotropy energy. REFERENCES [1] I. M. Miron et al., Nature 476, 189 (2011) [2] S. Ikeda et al., Nature Materials 9, 721 (2010) [3] C.-F. Pai et al., Appl. Phys. Lett. 101, 122404 (2012) ACKNOWLEDGMENTS Funding from the E.C. through a FP7-ICT project (Grant No. 318144) is acknowledged.

V.8.4
 
Poster Session 2 : chairs Maria Dinescu, Livia Giordano
17:30
Authors : L.C. Nistor, R. F. Negrea, S.V. Nistor, I. Vlaicu
Affiliations : National Institute of Materials Physics, Atomistilor 105 bis, Magurele, Ilfov, Romania

Resume : Dopants play a key role in providing alternative means for controlling the remarkable properties of semiconducting nanocrystals. Efforts were made to obtain small cubic ZnS (cZnS) nanocrystals (sizes < 5nm) doped with transition metal ions, for a broad range of applications. Here we report spatially resolved EELS (Electron Energy Loss Spectroscopy) analyses of Mn-doped mesoporous nanocrystalline cZnS, prepared by precipitation in a surfactant-assisted liquid-liquid reaction. The analyses were performed with the atomic resolution analytical transmission electron microscope JEOL JEM-ARM/200F. Spatially resolved EELS can be performed in two configurations: EFTEM (Energy Filtered TEM), in which a fixed electron beam illuminates a large region from where filtered images are acquired and SI (Spectrum Imaging), were a focused beam scans the sample and an EEL-spectrum is recorded at each pixel of the scan. Both methods provide the spatial distributions of elements, i.e. elemental maps. HRTEM investigations shows the mesoporous structure of the sample formed by agglomerates of cZnS nanocrystallites of 2 - 4 nm diameter and pores of the same sizes. Preliminary EELS elemental analyses revealed a non-uniform distribution of Mn impurities in the sample, a very high content (30-40%) of oxygen, a significant content of carbon and sometimes a small content of N. O, C and N originate from the preparation method. We try to answer the question where the Mn, O, C, and N atoms are distributed.

V.V II.1
17:30
Authors : Mariana Stefan, Daniela Ghica, Sergiu V. Nistor, Adrian V. Maraloiu; Rodica Plugaru
Affiliations : National Institute of Materials Physics, P.O. Box MG-7, 077125 Magurele, Romania; National Institute for R & D in Microtechnologies (IMT), Erou Iancu Nicolae Str. 126A, 077190 Bucharest, Romania

Resume : Magnetic and electrical properties of the nanostructured ZnO films are affected by the non-random impurities distribution in the film due to segregation at grain boundaries (GBs) or extended defects. Currently used methods for mapping the nature and distribution of low concentration (< 1%) of impurities are very complex and laborious. Electron paramagnetic resonance (EPR) spectroscopy provides a simple, statistically relevant and non-destructive method for the identification, quantitative evaluation and determination of the localization of the paramagnetic impurities present in nanostructured films. We used this technique to determine the distribution of the Mn(II) ions in two sol-gel deposited ZnO films, doped with 0.1% and 1% manganese, respectively. In the case of the low concentration doped film, all Mn(II) ions were localized as isolated ions at GBs. In the case of the ZnO film doped with 1% Mn, besides the isolated Mn(II) ions, the formation of a separate manganese-rich phase in the intercrystalline region was observed. Annealing at 600 oC induced important changes in the Mn(II) ions distribution in both films. The EPR results were correlated with transmission electron microscopy investigations.

V.V II.2
17:30
Authors : Prof. Alexander Pogrebnjak; Dr. Oleksandr Bondar
Affiliations : Sumy State University (Sumy, Ukraine)

Resume : Superhard Ti-Si-N coatings were fabricated using vacuum arc evaporation of cathode. Such methods of analysis as slow positron beam (SPB), RBS, µ-PIXE (proton microbeam), XRD, SEM with EDS, XPS, nanohardness and elastic modulus measurements were applied to investigation of such coatings, before and after annealing at the temperature of 600 degrees C for 30 minutes. Redistribution of N and Si occurred on the borders of nanograins after annealing, amorphous phase α-SiNx (Si3N4) was created, defects segregated on interfaces and formed vacancy-type clusters with rather high concentration from 5х10^16 cm^(-3) to 7.5x10^17 cm^(-3) due to thermodiffusion. Solid solution (Ti,Si)N and small concentration of α-SiN (close to XRD detection limits) were formed in the coatings. Deformation reduced after thermal annealing to a value of –2.3%. Size of nanograins of (Ti,Si)N solid solution increased from 12.5 nm to (13.2÷13.4) nm, and 25 nm grains increased to 28.5 nm due to annealing under another deposition regime. Fabricated coatings were implanted by high dose Cu- ions 2x10^17 см^(-2), kinetic energy was 60 keV in order to investigate the limits of irradiation resistance.

V.V II.3
17:30
Authors : Dorota Brzuska1, Daniel Jastrzebski1, Maciej Bialoglowski1, Edyta Pesko1, Cezariusz Jastrzebski2, Slawomir Podsiadlo1
Affiliations : 1 Faculty of Chemistry, Warsaw University of Technology; 2 Faculty of Physics, Warsaw University of Technology

Resume : Among various materials being explored in search for silicon replacement in nanoelectronics, SnS2 seems to be especially valuable. Having intrinsic layered structure of crystallites and relatively high energy gap offers multiple sophisticated applications, e.g. in high on/off current field effect transistors. In this study, structural and electron properties of SnS2 nanopowders have been examined. The syntheses have been carried out in aqueous solutions, as well as in organic solvents, using metal salts, sulfur, thioacetamide etc. The obtained materials have been characterized with X-ray powder diffraction, Raman scattering spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and spectrophotometry UV/Vis/NIR.

V.V II.4
17:30
Authors : VICTOR JAYA NESAMONY
Affiliations : DEPARTMENT OF PHYSICS ANNA UNIVERSITY CHENNAI -600 025 INDIA

Resume : Polymer nanofibers have wide range of applications ranging from textiles to opto electronic devices such as sensors, filtering elements, MEMS etc. Nano fibers are defined as fibers with diameters on the order of 1 to 100 nanometers. Fabrication of nanofibers made by light emitting polymers and composites showing tunable emitting properties in the visible and near IR range (400-950nm). The light emitting nanofibers of polymers are realized by doping optically inert polymers with light emitting molecules, or by pure conjucated materials. We observed luminescence depending on dopant . Typically QDs can be excited by UV light and emit visible light. Due to quantum confinement effect QDs exhibit photo luminescence properties by controlling bandgap. Light emitting polymer nanofibers are prepared by electrospinning technique which can produce a continuous, uniform fibers through an electrically charged jet of polymer solution or polymer melt. Nanofiber arrays can be conventionaly transferred onto various surface for many applications, including fabrication of nano devices and the characterization of nano fiber properties done by SEM, RAMAN, XRD and PL spectrum.

V.V II.5
17:30
Authors : A.B. SMIRNOV, R.S. UDOVYTSKA, R.K. SAVKINA, and F.F. SIZOV
Affiliations : V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 41, Prospect Nauky, 03028 Kyiv, Ukraine, phone: +38(044) 525 18 13

Resume : In this paper formation process of nano-heterostructures Ag2O-Hg1–xCdxTe(x=0.2) on the surface of solid solution Hg1–xCdxTe (х~0.22) has been investigated. Modification of the ternary chalcogenide semiconductor compound was performed using the method of doping the heterostructure samples with silver ions which was followed by low-temperature treatment. The energy and dose of implanted ions were 100 keV and 4.8x1013сm-2, respectively, the duration of thermal treatment was 5 hours at the temperature of 75ºС. The silver ion migration in the ion-disordered HgCdTe layer and local deformation defects are lead to the topological instability of the irradiated surfaces. The results of topometry based on AFM measurements show the network of quasi-pores with depth from 3.5 to 10 nm and diameter 50 to 160 nm, as well as grains with size 40 to 80 nm densely packed in the surface plane. After implantation with silver ions on the background of insignificant smearing of grain boundaries, with maintenance of initial surface porosity, a uniform array of cone-like spikes was formed, with height h from 5 to 25 nm and base diameter d between 13 and 35 nm. The magnitude of mechanical stresses created in the CdHgTe film after its implantation can be determined (σmax= 2.2x105 Pa). The coefficient of crystal lattice contraction by the introduced implant β was determined using the results of X-ray diffraction studies of specimens ~ 3.51x10-31m3. Deformations arising after embedding silver ions prevent the process of mercury diffusion in the implanted target. Apparently, transformation of the defect structure in semiconductor film reflects elastic relaxation “compression – extension – compression” in the region of MCT loosened by ion implantation.

V.V II.6
17:30
Authors : E. S. Bârcă1, C. Luculescu2, M. Filipescu2, V. Ion2, N.L. Dumitrescu2, M. Dinescu2, M. Abrudeanu1, C. Munteanu3
Affiliations : 1. Universitatea din Pitesti, Facultatea de Mecanica si Tehnologie, 110040, str Targul din Vale nr 1, Pitesti, Arges 2. National Institute for Lasers, Plasma and Radiation Physics, P.O. Box MG 16, RO 77125 Magurele - Bucharest, Romania 3. Universitatea Tehnica "Gheorghe Asachi" Iasi, Facultatea de Mecanica, Bld D. Mangeron nr. 61, 700050

Resume : Cerium oxide (CeO2) thin films have been deposited on Si (100) and steel substrates using pulsed laser deposition technique at different substrate temperatures from room temperature (RT) up to 500C in a controlled atmosphere of oxygen (0.1 mbar). Structural, morphological and optical properties have been investigated using X-ray diffraction (XRD), Raman, scanning electron microscopy and ellipsometry techniques. The refractive index is increasing (1.53 - 2.2) with the increasing of the substrate temperature. XRD results showed that the deposited films are polycrystalline with cubic structure. The Raman peak appeared at 460 cm−1 due to the F2g active mode. Nanostructured “pyramids” like features were observed for high temperature substrate.

V.V II.7
17:30
Authors : A.M. Titenko1, L.D. Demchenko2, S.I. Sidorenko2
Affiliations : 1 Institute of Magnetism, NAS of Ukraine, Acad. Vernadskiy avenue, 36-b, Kyiv, 03142, Ukraine, titenko@imag.kiev.ua; 2 National Technical University of Ukraine "Kyiv Polytechnic Institute", Peremogy prospect, 37, Kyiv, 03056, Ukraine, lesyademch@gmail.com

Resume : Aging Cu-Mn-Al alloys with original magnetic characteristics undergo thermo-induced martensitic transformation (MT). Nowadays, such type of MTs which occur after solid solution decomposition with ferromagnetic nanoparticles precipitation in nonferromagnetic matrix attract interest. By thermal treatment, the system of ferromagnetic nano-dispersed particles in nonferromagnetic matrix can be formed. Herewith, coherent nanoparticles precipitated during decomposition of high-temperature Cu-Al-Mn betta1-phase are coherently connected with matrix and do not undergo spontaneous MT at cooling . The influence of aging regimes of high-temperature phase on subsequent martensitic transformation in Cu-Al-Mn alloy was studied. The morphology of martensitic transformation behavior as a result of alloy aging under an annealing in a constant magnetic field with different sample orientation relatively to the field and without the field was investigated for directly control of the process of martensite induction at cooling. The temperature dependences of electrical resistance, magnetic susceptibility, and the temperature and field dependences of magnetization, phase composition were found. The tendency of oriented growth of the precipitation-phase particles in a direction of applied field and the increase of volume fraction of these particles under thermal magnetic treatment of material what favors a reversibility of induced martensitic transformation.

V.V II.8
17:30
Authors : L. Floroian, M. Badea, C. Samoila, N. Mihailescu, I. Negut, V. Craciun, I.N. MIhailescu
Affiliations : Transilvania University of Brasov, Romania National Institute for Laser, Plasma and Radiation Physics, Magurele, Romania

Resume : We report on the transfer of novel polymer-antibiotic-bioactive glass composites by matrix assisted pulsed laser evaporation to uniform thin layers onto stainless steel implant. Influence of the deposition process on the structure of nanomaterials was studied. The targets were prepared by freezing in liquid nitrogen of mixtures containing polymer and antibiotic reinforced with bioglass powders. The cryogenic targets were submitted to multipulse ablation with an UV KrF* (λ=248 nm, τ ~ 25 ns) excimer laser source. The main advantages with this coating are multiple: stopping any leakage of metal and metal oxides to the biological fluids and finally to inner organs (by polymer use), speeding up osteointegration (by bioactive glass use), antimicrobial effect (by antibiotics use) and decreasing of the implant price (by cheaper stainless steel use). The behaviour of polymer-antibiotic-glass/stainless steel structure in condition which simulates the physiological environment was evaluated in vitro by complementary techniques. The bioactivity and the release of the antibiotic were assessed by immersion into simulated body fluid and monitoring by FTIR and UV-VIS spectrometry and electrochemical measurements involving corrosion and EIS studies were carried out in order to investigate the corrosion resistance. The biological properties were tested including the microbial viability using Gram - and Gram + bacterial strains, the microbial adherence and the cytotoxicity on eukariotic cell.

V.V II.9
17:30
Authors : 1.Ana Maria Niculescu,2.Claudiu T.Fleaca, 3.Monica Scarisoreanu, 4.Marius Dumitru , 5.Catalin Luculescu, 6.Maria Dinescu , 7.Ion Morjan
Affiliations : 1National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest- Magurele, Romania , 2 1National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest- Magurele, Romania and "POLITEHNICA"University of Bucharest,Physics Department , Independentei 313 , Bucharest, Romania , 3National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest- Magurele, Romania , 4.1National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest- Magurele, Romania , 5.National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest- Magurele, Romania , 6.1National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest- Magurele, Romania , 7.1National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest- Magurele, Romania

Resume : The aim of this work is to compare two nanopowders obtained with different methods deposited by laser techniques. Mixed oxide nanoparticles containing different Ti:Sn atomic ratio were synthesized starting from sensitized mixtures of TiCl4 and Sn(CH3)4 precursors using laser pyrolysis technique. Tin oxide-based nanocomposites were obtained by glycine combustion technique starting from organometallic titanium tetraizoporpoxide and tetrabutyl-bis(acetyloxi) distanoxane. Structural and morphological properties of the obtained nanoparticles have been characterized by small particle sizes and structural homogeneity using XRD and TEM. Both anatase and rutile phases were identified in the resulted nanoparticles. The nanopowders were dispersed in aqueous media at different concentration using ultrasonication. Their hydrodynamic size distributions were evaluated before deposition by DLS (Dynamic Light Scattering). The water-based mixtures were frozen in liquid nitrogen and deposited using MAPLE (Matrix Assisted Pulsed Laser Evaporation) on silicon substrates and interdigitated electrodes. The thin films deposited on silicon substrates were analysed using TEM, XRD, SEM and EDX techniques. The obtained thin films deposited on interdigitated electrodes were tested at different gases. The electrical measurements were performed during heating process using different gas flows, starting from 5000 ppm until 100 ppm. The temperature range was around 300- 350 C, maintained for 3 hours at 350C.

V.V II.10
17:30
Authors : Ricardo Paupitz, Chad E. Junkermeier, Paulo S. Branicio, Adri C.T. van Duin
Affiliations : Departamento de Fisica, IGCE, Universidade Estadual Paulista, 13506-900, Rio Claro, SP, Brazil; Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park PA 16802, USA; Institute of High Performance Computing, 1 Fusionopolis Way, \#16-16 Connexis, Singapore 138632, Singapore; Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park PA 16802, USA

Resume : Statical and dynamical aspects of a class of macromolecules based on the architecture of the well known fullerenes is theoretically investigated. The building blocks used to geometrically construct these molecules are the two dimensional structures: porous graphene and biphenylene-carbon. Density Functional-based tight binding (DFTB) methods as well as reactive molecular dynamics (ReaxFF) methods are applied to study the electronic and structural properties of these molecules. Our calculations predict that these structures can be stable up to temperatures of 2500K. The atomization energies of carbon structures is predicted to be in the range 0.45 eV/atom to 12.11 eV/atom (values relative to the C60 fullerene), while the BN analogues have atomization energies between -0.17 eV/atom and 12.01 eV/atom (compared to the B12N12 fullerene). Due to their high porosity, these structures may be good candidates for gas storage and/or molecular encapsulation. This possibility of encapsulation is explored using DFTB methodology. For this end, several DFTB based molecular dynamics simulations were carried in order to obtain new insights regarding mechanisms involved in the possible encapsulation of small molecules by these compounds.

V.V II.11
17:30
Authors : M.C. Spadaro1,2, S. D?Addato1,2, F. Benedetti1,2, G. Gasperi1,2, P. Luches2,V. Grillo2,3, G. Bertoni3,4, S. Turner5, G. Van Tendeloo5 and S. Valeri1,2
Affiliations : 1 Dipartimento FIM, Universit? di Modena e Reggio Emilia, via G. Campi 213/a, Modena, Italy 2 CNR-NANO, S3 Research Centre, via G. Campi 213/a, Modena, Italy 3 CNR-IMEM, Parco Area delle Scienze 37/A - 43124 Parma, Italy 4 Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy 5 EMAT, University of Antwerp, Antwerp, Belgium

Resume : CeO2-x nanoparticles (NPs) is a widely studied system because of its ability to store and release oxygen depending on the ambient conditions because of the switch between the Ce3 and Ce4 chemical states. Because of this ability, ceria is important in industrial catalysis, fuel cells and in biomedical applications to prevent the oxidation of human cells. In our work CeO2-x NPs were obtained with a gas aggregation source with a magnetron and a quadrupole mass filter. We oxidized the samples in different conditions in order to select the best oxidation procedure in terms of reducibility [(a)NPs deposited in vacuum (without oxygen), (b) deposition in oxygen atmosphere inside the deposition chamber and post oxidation and (c) deposition in oxygen atmosphere inside the aggregation chamber]. Then, in order to evaluate the contribution of the exposed planes to the NPs reducibility, we compared the reducibility of these NPs with the CexO2-x epitaxial islands ones (CexO2-x epitaxial islands were grown with the same aspect ratio as the NPs) exposing the (111) planes. Successively, we performed a study on how NPs reducibility is related with NPs size, producing NPs with an average diameter of 6 nm, 9 nm and 15 nm, varying power to the magnetron, Ar gas flow and aggregation tube length. On those systems we performed also SEM analysis to investigate their morphology, and in order to gain a deeper insight into the atomic structure and oxidation state of single NPs we performed some HR-TEM

V.V II.12
Start atSubject View AllNum.
 
Session 9 : chair Luisa Spallino
09:00
Authors : Chi Lun Pang
Affiliations : Department of Chemistry and London Centre for Nanotechnology, University College London, London WC1H 0AJ, UK.

Resume : Metal oxide-supported metal nanoparticles find application in fields as diverse as nano-electronics and heterogeneous catalysis. This has led to intense study of model systems that consist of metal nanoparticles supported on single crystal oxides. Here, I will present our recent work concerning well-defined Pd nanoparticles formed on TiO2(110). These nanoparticles grow both on flat terraces and across step edges. The behaviour of these Pd nanocrystals was probed by adsorption of CO and O2. For CO, several different overlayer structures were detected in scanning tunneling microscopy (STM). While most of the CO structures match with observations and expectations from work on single crystal Pd(111), two previously unobserved CO structures were found. With the help of calculations, we attribute these novel phases to the strain on the nanoparticle, induced by carpet growth across the TiO2(110) step edges.

V.9.1
09:30
Authors : Manuel Roussel, Guido Schmitz
Affiliations : University of Stuttgart Institute for Materials Science

Resume : The formation of hollow particles has been extensively studied during the past few years, and this enthusiasm assuredly comes from the fact that nanometric containers may have several applications in various fields (catalysis, drug delivery, composite materials…). Our work focuses on investigating the mechanisms which are involved during the creation of a hollow particle at the atomic scale. More precisely, we try to understand the link between solid state diffusion, non-equilibrium vacancies and diffusion-induced stresses during the formation of a “Kirkendall void” in core-shell nanostructures. Here, emphasis will be placed on showing how diffusion and phase transformation can be controlled using stress and geometry in core-shell metallic nanostructures. Finite element simulations allow us to apprehend the problem from a theoretical point of view. As an example, we will show how switching from a nanosphere to a nanowire configuration can drastically change diffusion kinetics at the atomic scale. We also have a powerful characterization tool at our disposal, the Tomographic Atom Probe. This tool provides us with a 3D chemical map of our samples at the atomic scale. It will allow us to show how important the presence of defects at the nanoscale in real samples can be. For instance, grain boundaries can imply tremendous changes during diffusion in these core-shell nanostructures.

V.9.2
09:50
Authors : Camila Mallmann, Aude Simar, Emilie Ferrié, Marc Fivel, Erica T. Lilleodden
Affiliations : Simap-GPM2; UCL-iMMC-IMAP; Simap-GPM2; Simap-GPM2; Helmholtz-Zentrum Geesthacht

Resume : Mg based nanocomposites have attracted much attention as a promising structural material to save energy and reduce emissions in the automotive and aerospace sectors. Mg is the lightest of all structural metals; however, its strength needs to be improved in order to compete with other light metals such as Al and Ti. The present work investigates the plastic behavior of Mg nanocomposite single crystal strengthened by oxide dispersed particles, in comparison to that of pure Mg. Y2O3 reinforced Mg matrix composites were elaborated by friction stir processing. FSP proves to be an efficient method to produce metal-based composites: the particles are well dispersed and have an average size of some hundreds nanometers. Micropillars were fabricated in a single grain with a known orientation using FIB machining. The mechanical response was investigated using microcompression testing. The advantage of this method over traditional mechanical testing for studying the mechanisms of deformation is that the entire sample can be investigated post-mortem. Microcompression experiments were conducted in a nanoindenter. The stress-strain response was measured for different single crystal orientations. In addition to experimental investigations, 3D discrete dislocation dynamics simulations were carried out for comparison. The results provide relevant insights on the role of nanoparticles on the onset of plastic deformation in single crystals as well as twinning nucleation in Mg nanocomposites.

V.9.3
10:10
Authors : Alexander Leitner, Verena Maier, Peter Hosemann, Daniel Kiener
Affiliations : Department Materials Physics, Montanuniversität Leoben, Jahnstraße 12, A-8700 Leoben, Austria; Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Jahnstraße 12, A-8700 Leoben, Austria; Department of Nuclear Engineering, University of California, Berkeley 4155 Etcheverry Hall, MC 1730, Berkeley, CA 94720-1730, USA; Department Materials Physics, Montanuniversität Leoben, Jahnstraße 12, A-8700 Leoben, Austria

Resume : Current trends regarding design and engineering of highly efficient miniaturized devices and machines require innovative materials to satisfy requirements such as high strength at low density. The purpose of the present study was to investigate mechanical properties and deformation behavior of nanoporous Au and its ultra-fine grained bulk counterpart, both fabricated from the same base material. Microstructural investigations of the foam showed a ligament size of ~100 nm consisting of ~60 nm diameter grains in average, while the ultra-fine grained Au exhibits an average grain size of 250 nm. Nanoindentation lends itself as the method of choice to obtain local materials properties, at room temperature as well as at elevated temperatures, respectively. We performed a series of indentation tests and nanoindentation relaxation experiments to determine hardness, Young’s modulus, strain-rate sensitivity, and activation volume from room temperature to elevated temperatures up to 300 °C for the porous and bulk materials. Due to the small characteristic dimensions in terms of grain size or ligament diameter, high hardness values were determined for both materials, which rapidly drop at elevated temperatures. In addition, an enhanced strain-rate sensitivity accompanied by low activation volumes was determined, increasing with temperature for both states. We associate this mechanical behavior with interactions between dislocations and grain boundaries or free surfaces, respectively.

V.9.4
10:30 Coffee break    
 
Session 10 : chair Pang Chi Lun
11:00
Authors : E. Khestanova [1], N. Dix [1], I. Fina [1], J.M Rebled [1,2], C. Magen [3], S. Estrade [2], F. Peiro [2], J. Fontcuberta [1] and F. Sanchez [1]
Affiliations : [1] Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Spain; [2] LENS - MIND/IN2UB, Universitat de Barcelona, Spain; [3] Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA) – ARAID , Zaragoza, Spain

Resume : Superlattices (SPLs) consisting of ferroelectric/paraelectric oxide layers present a large interest due to their flexibility for tuning of ferroelectric properties. In such SPLs a large number of interfaces are present, and additionally the lattice strain in the SPLs can differ notably with respect to single phase films. Discerning between strain and interface effects on the ferroelectric properties constitutes a bottleneck. We have fabricated BaTiO3/SrTiO3 (BTO/STO) SPLs by pulsed laser deposition (PLD) assisted by high pressure reflection high energy electron diffraction (RHEED). RHEED and atomic force microscopy confirm persistent layer-by-layer and atomically flat surfaces in complex M x (n-BTO / n-STO) SPLs, with period n from 1 to 10 and M adjusted to have total of 120 monolayers. X-ray reflectivity and X-ray diffractometry (XRD) patterns show Kiessig and Laue fringes signaling the high quality of the samples. XRD reciprocal space maps and high resolution transmission electron microscopy confirmed coherent growth. Polarization loops were measured, with remnant polarization (Pr) from a few μC/cm2 to more than 20 μC/cm2, increasing (decreasing) with the number of interfaces (STO thickness in each period). We present a thin film growth strategy that permits changing lattice strain for a fixed M x (n-BTO / n-STO) SPL architecture, and we show that Pr is much less sensitive to lattice strain than to the number of interfaces.

V.10.1
11:30
Authors : A. Wisniewski1, I. Fita1, V. Markovich2, R. Puzniak1,
Affiliations : 1 Institute of Physics, PAS, Al. Lotnikow 32/46, PL-02-668 Warsaw, Poland; 2 Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva, Israel

Resume : Pressure effect on magnetic state and exchange bias (EB) in phase-separated ferromagnetic/antiferromagnetic (FM/AFM) CaMn1-xRuxO3 (0.06 < x < 0.15) and Bi0.4Ca0.6Mn1-xRuxO3 (x = 0.1, 0.2) manganites was studied under a pressure up to 11 kbar. For both manganites, complex pressure and Ru-doping effects on EB and coercive fields may be explained with a model of size-variable (depending on Ru content and pressure) nanoscale FM droplets embedded in an AFM matrix. For Bi0.4Ca0.6Mn1-xRuxO3, it was found that the x = 0.2 composition is basically ferromagnetic while the low-doped (x = 0.1) one exhibits a FM cluster glass behavior and EB effect at low temperatures. For this compound, both Ru-doping and external pressure act similarly, leading to a growth of the FM clusters and consequently to a suppression of the EB. For La0.9Ba0.1CoO3 cobaltite, exhibiting the ferromagnetic cluster-glass behavior and EB effect at low temperatures, it was found that an applied pressure increases the temperature below which the FM clusters appear, and enlarges the FM phase volume in the sample. Applied pressure was found to suppress strongly the EB. Overall, the pressure-induced diminution in HEB is explained by considering an increase of the FM cluster size and by concomitant decrease of distance between clusters. The results show that for phase-separated FM/AFM manganites and FM/SG cobaltites the EB effect may be controlled by external pressure because of pressure-dependent size of FM clusters.

V.10.2
11:50
Authors : C. N. Mihailescu1, 2, E. Symeou1, R. Negrea3, C. Ghica3 and J. Giapintzakis1*
Affiliations : 1Nanotechnology Research Center and Department of Mechanical and Manufacturing Engineering, University of Cyprus, 75 Kallipoleos Avenue,PO Box 20537, 1678 Nicosia, Cyprus 2National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-36, 077125 Magurele, Romania 3National Institute of Materials Physics, RO-077125 Magurele, Romania

Resume : Vanadium dioxide (VO2) with its reversible metal-insulator transition (MIT) close to room temperature (341 K in single crystals) is attracting more and more interest due to the increasing number of applications in which it can be used. The constant and technologically relevant need of lowering its transition temperature (TMI) has resulted in an impressive number of theoretical and experimental studies investigating the influence of the substrate nature and crystallographic orientation, layer thickness, growing temperature, effect of doping, hydrogenation, interface quality, usage of an buffer layer or interfacial strain. Among them, the interfacial strain is considered as the most straightforward way to modulate the TMI. In this talk, we will present our recent results on VO2 thin films grown over a wide temperature range, and discuss the effect of interfacial strain on the TMI determined by electrical measurements. The films have been grown on low-miscut (0 0 1) TiO2 substrates by Pulsed Laser Deposition (PLD). Their crystal structure has been studied by high resolution X-ray diffraction (HR-XRD) and high resolution transmission electron microscopy (HR-TEM), while the quality of the interfaces (microstructure and stoichiometry) has been characterized by HR-TEM and Electron Energy Loss Spectroscopy (EELS). The strain nature of the films has been evaluated from HR-XRD and Geometrical Phase Analysis (GPA) measurements.

V.10.3
12:10
Authors : Sergiu V. Nistor, Mariana Stefan, Leona C. Nistor, Daniela Ghica
Affiliations : National Institute of Materials Physics, Atomistilor 105 bis, Magurele-Ilfov, Romania 077125

Resume : Ultrasmall zinc sulfide nanocrystals with cubic (blende) structure, doped with Mn2+ ions, have been prepared by colloidal synthesis [1] at pH = 8. According to XRD and HRTEM measurements they exhibit a core-shell structure, with a crystalline cZnS core of 2 nm average diameter and a shell of disordered, orthorhombic e-Zn(OH)2 of 0.3 to 1.9 nm thickness [2]. The analysis of the electron paramagnetic resonance spectra of the low concentration Mn2+ ions used as local atomic probes during pulse annealing experiments [3] resulted in the observation of a three-steps thermal decomposition of the e-Zn(OH)2 shell into nanostructured ZnO, in the 80-450 oC range, instead of a direct decomposition into crystalline ZnO at 120 oC, observed for the crystalline bulk e-Zn(OH)2 shell. This unusual behavior is explained by the sequential decomposition by dehydration of the disordered Zn(OH)2 shell into two new intermediate oxyhydrated Zn nanocompounds, which are not stable in the bulk form. Our results demonstrate that the chemistry of nanosized compounds can be different from the chemistry of the bulk counterparts. [1] S. V. Nistor et al., Superlattices Microstruc. 46 (2009) 306 [2] S. V. Nistor et al, J. Chem. Phys. C 42 (2013) 2217 [3] S. V. Nistor et al., J. Therm. Analys. Calorim. 118 (2014) 1021

V.10.4
12:30 Lunch break    
 
Session 11 : chair Sergio D'Addato
14:10
Authors : Shaun Mills*, Eoin K. McCarthy, John E. Sader and John J. Boland
Affiliations : Centre for Research on Adaptive Nanostructures and Nanodevices, School of Chemistry, Trinity College Dublin, Dublin 2, Ireland.

Resume : Metallic nanowires show potential for use in a range of applications, including but not limited to sensing, actuators and NEMs[1] (Nano-Electromechanical systems) devices. However, before nanowires can be incorporated into functional devices, it is important to fully understand their mechanical properties. There is a pre-existing stress associated with wires deposited on an Si/SiO2 surface in the form of tension or compression[2]. It is essential to establish whether this pre-existing stress is inherent in the wire or if it is a result of deposition onto a substrate. This must be understood prior to the incorporation of wires into functional devices as the stress can have a profound effect on the measured stiffness. This project focuses on the use of a three point AFM bending experiment previously developed in our lab[3] whereby the Young’s Modulus of individual nanowires was extracted. Nanowires are suspended over pre-defined trenches etched in SiO2. This allows lateral manipulation of the wire perpendicular to its long axis without friction effects between the wire and the substrate. Through careful tip calibration[4] the lateral deflection on the photodiode can be converted to produce a Force-Displacement curve. This Force-Displacement curve is then fitted to the Sader model[5] for a clamped-clamped beam. For measurements made on these wires the original Sader model was adjusted to account for a pre-existing stress found in the data. The wires measured in this work were kept in the elastic regime to ensure repeated manipulations of individual metallic nanowires could be performed. It was established that the pre-existing stress can vary considerably through subsequent manipulations of the same wire. Further investigation into the basis of this pre-existing stress is required before these wires can be incorporated into devices such as interconnects or NEMs devices. [1] O. Y. Loh and H. D. Espinosa, “Nanoelectromechanical contact switches.,” Nat. Nanotechnol., vol. 7, no. 5, pp. 283–95, May 2012. [2] Y. Calahorra, O. Shtempluck, V. Kotchetkov, and Y. E. Yaish, “Young’s Modulus, Residual Stress, and Crystal Orientation of Doubly Clamped Silicon Nanowire Beams.,” Nano Lett., Apr. 2015. [3] B. Wu, A. Heidelberg, and J. J. Boland, “Mechanical properties of ultrahigh-strength gold nanowires.,” Nat. Mater., vol. 4, no. 7, pp. 525–9, Jul. 2005. [4] U. D. Schwarz, P. Koester, and R. Wiesendanger, “Quantitative analysis of lateral force microscopy experiments,” Rev. Sci. Instrum., vol. 67, no. 7, pp. 2560–2567, 1996. [5] A. Heidelberg, L. T. Ngo, B. Wu, M. A. Phillips, S. Sharma, T. I. Kamins, J. E. Sader, and J. J. Boland, “A Generalized Description of the Elastic Properties of Nanowires,” pp. 2–7, 2006.

V.11.1
14:30
Authors : Osamu Waseda, Michel Perez, Julien Morthomas, Roberto Veiga
Affiliations : Laboratoire MATEIS INSA de Lyon, Departamento de Engenharia Metalúrgica e de Materiais, Universidade de Saõ Paulo

Resume : Despite the intensive studies of ageing of steels over the course of years, the structure of Cottrell atmospheres, the kinetics of their creation, as well as the pinning force exerted on the dislocation are not well understood. In our study, we develop a Monte Carlo (MC) simulation framework, that searches for the energetically best configuration of carbon atoms in bcc crystal iron in a small simulation box containing an edge dislocation. Then in regular MC steps, it is incorporated into a larger simulation box to allow the boundaries of the small simulation box to attain a stress-free configuration. This eventually leads to the creation of Cottrell atmospheres in different development levels. Subsequently, the behaviour of the dislocation as well as the Cottrell atmosphere is scrutinized in various stress fields to understand the effect of Cottrell atmospheres on the stress-strain relation.

V.11.2
14:50
Authors : Jonathan J. Bean, Keith P. McKenna
Affiliations : Department of Physics, University of York

Resume : The excess volume associated with grain boundaries is one of the primary factors driving defect segregation and diffusion which controls the electronic, mechanical and chemical properties of many polycrystalline materials. We employ a high throughput computational approach to determine the atomic structure, formation energy and excess volume of a large number of tilt grain boundaries in Cu, Fe and Ni. By considering 400 distinct grain boundary orientations we obtain characteristic statistical distributions of excess volume for each metal. We obtain average excess volumes of 0.37 +/- 0.07 Ang, 0.25 +/- 0.10 Ang and 0.21 +/- 0.07 Ang for Cu, Fe and Ni respectively, in broad agreement with experimental measurements. The distributions show that the maximum excess volume may in some cases be up to 50\% larger than the average. This suggests some grain boundaries may be particularly susceptible to defect segregation and may play a decisive role in important effects such as hydrogen or helium embrittlement. We find broad and complex distributions which are distinct for each material and these may provide invaluable guidance for optimization of polycrystalline materials for applications.

V.11.3
15:10 Coffee break    
 
Session 12 : chair Maria Dinescu
16:10
Authors : Shih-Chen Hsu, Michael H. Huang
Affiliations : Department of Chemistry, National Tsing Hua University

Resume : It is interesting to examine facet-dependent electrical properties of single Cu2O crystals, since such study greatly advances our understanding of various facet effects exhibited by semiconductors. We show a Cu2O octahedron is highly conductive, a cube is moderately conductive, and a rhombic dodecahedron is non-conductive. The conductivity differences are ascribed to the presence of a thin surface layer having different degrees of band bending. When electrical connection was made on two different facets of a rhombicuboctahedron, a diode-like response was obtained, demonstrating the potential of using single polyhedral nanocrystals as functional electronic components. Density of state (DOS) plots for three layers of Cu2O (111), (100), and (110) planes show respective metallic, semimetal, and semiconducting band structures. By examining DOS plots for varying number of planes, the surface layer thicknesses responsible for the facet-dependent electrical properties of Cu2O crystals have been determined to be below 1.5 nm for these facets.

V.12.1
16:30
Authors : E. Symeou 1, C. N. Mihailescu 1, 2, M. Pervolaraki 1 and J. Giapintzakis1
Affiliations : 1. Nanotechnology Research Center and Department of Mechanical and Manufacturing Engineering, University of Cyprus, 75 Kallipoleos Av., PO Box 20537, 1678 Nicosia, Cyprus ;2. National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor St., PO Box MG-36 077125, Magurele, Romania

Resume : Nowadays there is a strong belief that thermoelectric thin film-based devices represent a suitable route to mitigate thermal management problems in micro- and nano-electronics. Bi0.5Sb1.5Te3 (BST) is considered to be a state-of-the-art p-type thermoelectric material, at temperatures near room temperature, due to its high power factor value. Nevertheless, the deposition of BST thin films with bulk-like thermoelectric properties remains a challenge because of issues related to stoichiometry and antisite defects. There is still a need for investigating the effect of chemical compositions on the thermoelectric properties of BST thin films. We have grown p-type Bi0.5-xSb1.5Te3+x thin films onto different types of substrates using pulsed laser deposition at 248nm and home-made targets with different Bi concentrations, and investigated their structural, electrical and thermoelectrical properties. In this talk, we will present our recent results on Seebeck coefficient, electrical resistivity and Hall carrier concentration as a function of temperature for a series of Bi0.5-xSb1.5Te3+x thin films. We will discuss how their thermoelectric properties are affected by the substrate type and Bi content. Also, we will address the effect of post-annealing treatment on their structural and thermoelectric properties.

V.12.2
16:50
Authors : Antonio Cammarata, Tomas Polcar
Affiliations : Czech Technical University in Prague, Department of Control Engineering, Czech Republic; Czech Technical University in Prague, Department of Control Engineering, Czech Republic and Engineering Materials & nCATS, FEE, University of Southampton, United Kingdom

Resume : One of the main difficulties in understanding and predicting frictional response is the intrinsic complexity of highly non-equilibrium processes in any tribological contact, which include breaking and formation of multiple interatomic bonds between surfaces in relative motion. To understand the physical nature of the microscopic mechanism of friction and design new tribologic materials, we conducted a systematic quantum mechanic investigation at the atomic scale on the geometric, electronic and dynamic properties of prototipical MX2 (M=Mo, W; X=S, Se, Te) Transition Metal Dichalcogenides under variable load. We have been able to disentangle the electro-vibronic contribution to the frictional response by adopting a new investigation protocol: we combined the structural and dynamic information from group theoretical analysis and phonon band structure calculations with the characterisation of the electronic features using non-standard methods like orbital polarization and the recently formulated bond covalency and cophonicity analyses. The vibrational modes relevant during tribological conditions are individuated, quantified and put in relation with the atomic types and the electronic features that the latter determine. Guidelines on how to engineer macroscopic friction at nanoscale are formulated, and finally applied to design a new Ti-doped MoS2 phase. The formulated protocol can be promptly applied to the design of new materials with diverse applications other than tribology.

V.12.3
17:10 Conclusions: M. Dinescu    
18:00 Best Student Presentations Awards Ceremony and Reception - Main Hall    
Start atSubject View AllNum.
09:00 Plenary Session - Main Hall    

Symposium organizers
Maria DINESCUNational Institute for Lasers, Plasma and Radiation Physics

409 Atomistilor 77125 Magurele (Bucharest) Romania

+4021 457 44 14
dinescum@nipne.ro
Ioannis (John) GIAPINTZAKIS Nanotechnology Research Center and Department of Mechanical & Manufacturing Engineering | University of Cyprus

75 Kallipoleos Av. PO Box 20537 1678 Nicosia Cyprus

+357 22892283
giapintz@ucy.ac.cy
Marek WÓJCIK Institute of Physics, Polish Academy of Sciences

Al. Lotnikow 32/46 02-668 Warszawa Poland

+48 22 843 52 12
wojci@ifpan.edu.pl
Sergio D’ADDATO CNR-NANO and Dipartimento FIM Università di Modena e Reggio Emilia

via G. Campi 213/a 41125 Modena Italy

+39-059-2055254
sergio.daddato@unimore.it