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MATERIALS FOR ENERGY AND ENVIRONMENT

C

Substitution and recycling of critical raw materials in optoelectronic, magnetic and energy devices - II

Following the successful edition in 2016, the Symposium is devoted to academic and industrial partners working on the substitution and recyclability of critical raw materials (CRM) in electronic, magnetic and energy harvesting devices. The objective is to strengthen the synergies in this community and promote the development of new efficient CRM-free/lean devices.

Scope:

Raw materials are the basic, but fundamental, elements for a wealth of current technological applications. However, some of these materials have been recently defined by the EU commission as “critical” due to the high risk of supply shortage expected in the next 10 years and for their importance to the European industry. Thus, their (total or partial) substitution and recycling are essential for Europe’s economy.

Many technologies with a high impact on the quality of life rely on critical raw materials (CRMs) as key elements, from lighting devices (LED, OLED, CFL: rare earths, like Ce, Y, Eu and Tb, In  as CRMs) to energy harvesting devices (transparent conductive layers, solar absorbers), permanent magnets (SmCo, NdFeB), catalytic converters, electrode catalysts in fuel cells [Pt group metals (PGM) and Rh-based catalysts] and rechargeable batteries (rare earths, graphite, Co, Li and Ni as CRMs). New research and development activities are required to improve the fundamental understanding of new material solutions containing reduced or no critical content while maintaining or enhancing the performance of the materials, components and products. The design of the alternatives compounds, the control of growth process coupled with accurate characterization are mandatory for further development of new CRM-free/lean devices.

The symposium provides an interdisciplinary platform to discuss about CRM alternatives from the modelling, synthesis, characterization, processing and device integration viewpoints. Bringing together researchers from academia and industry we aim at increasing the interaction among scientists, engineers, and students working on different areas of the CRM field that are too often treated separately. The symposium is organized by members of the EIP RESET commitment, and will therefore be included and publicised within the program of activities of the commitment.

Hot topics to be covered by the symposium:

Materials Science, Design, Synthesis, Growth, Characterization of Advanced Materials with reduced or free from Critical Raw Materials for :

  • Transparent conductive layers
  • Phosphors for LED applications, Scintillators, Displays
  • OLEDs
  • Catalysis
  • Solar: photovoltaics, photocatalysis
  • Smart windows
  • Hydrogen storage materials
  • Exchange-coupled nanocomposite magnets with less or no rare earths
  • New RE-free/lean highly anisotropic magnetic materials
  • Recycling of critical raw materials

Invited speakers:

  • Alberto López-Ortega, CIC-Nanogune Consolider (San Sebastián, Spain): “Strongly Exchange Coupled Core|Shell Nanoparticles with High Magnetic Anisotropy: A Strategy Toward Rare-Earth-Free Permanent Magnets
  • Philippe Smet, University of Gent (Belgium): “Are alternatives needed for the workhorses Eu2+ and Ce3+ in phosphor converted LEDs?
  • Eva Brouwer, Fraunhofer ISC – Project Group Materials Recycling and Resource Strategies (Hanau, Germany): “Recycling of Nd-Fe-B magnets – one way to help ensuring Europe’s rare earths supply
  • Didier Zimmermann, EIT Raw Materials, Central co-location Centre (Metz, France), “Innovation in Critical Materials Value Chains: Science, Business, People
  • Claire Tutenuit, Entreprises pour l’Environnement (France), “Challenges of Environmental Constraints for Critical Raw Materials 
  • Shahzada Ahmad, Basque Center for Materials, Applications and Nanostructures (Spain), “Perovskites : A complimentary yet effective light harvesting material”
  • Maria Luisa Grilli, ENEA (Rome, Italy), “Optical characteristics of ultrathin Nickel films
  • Tetsuo Tsuchiya, National Institute of Advanced Industrial Science and Technology (Japan), “Advanced Components for Green Devices Produced by Materials Substituting Rare Metals or New Ceramic Coating Process
  • Svetlana Neretina, University of Notre Dame (Indiana, USA), “Understanding the Mechanisms of the Leaching of Catalytic Materials
  • Claudio Pistidda, Institute of Materials Research (Geesthacht, Germany), “Hydrogen storage systems from Mg wastes”.
  • Chaoyang Li, Kochi University of Technology (Japan), “Fabrication of novel ZnO/TiO2 core-shell nanostructures applying for dye sensitized solar cells
  • Jinwoo Lee, Pohang University of Science and Technology (South Korea), “Direct Access to Functional Porous Materials for Electrochemical Energy Storage
  • Ester M. Palmero, IMDEA Nanoscience (Madrid, Spain), “Polymerization of rare earth-free permanent magnet particles for advanced 3D printing technology

 

Scientific committee:

  • Roland Mathieu (Uppsala University, Sweden)
  • Peter Normile (UCLM, Spain)
  • Davide Peddis (CNRS, Italy)
  • Daniel Salazar (BCMaterials, Spain)
  • Alexander Buckow (Fraunhofer ISC, Germany)
  • Josep Nogués (ICN2, Spain)
  • Su Seong Lee (Singapore)
  • Alberto Bollero (IMDEA, Spain)
  • Per Nordblad (Sweden)
  • Pablo Muñiz (UCLM, Spain)
  • Tamio Endo (Japan)
  • Ester Vázquez (UCLM, Spain)
  • Maria Luisa Grilli (ENEA, Italy)
  • M. Cannas (University of Palermo, Italy)
  • M. L. Ruello (University of Marche, Italy)
  • Sebastiano Garroni (University of Burgos, Spain)
  • Riccardo Corpino (University of Cagliari, Italy)
  • Etienne Bouyer (CEA, France)
  • Santiago Cuesta-Lopez (University of Burgos, Spain)
  • Davide Prosperi (Urban Mining, USA)
  • Miha Zakotnik (Urban Mining, USA)
  • Rocco Lagioia  (ITRB Consulting)
  • Dario della Sala (ENEA, Italy)
  • J.-P. Vilcot (CNRS, France)
  • M.-P. Besland (CNRS, France)
  • S. Binetti (University of Milano-Bicocca, Italy)
  • Christian Hegelueken (Umicore, Belgium)
  • Wilfried Favre (CEA, France)
  • Joao Pedro Veiga (University of Lisboa, Portugal)
  • Guido  Sonnemann (University of Bordeaux, France)

Publication:

The papers will be published in a special issue of Physical Status Solidi A (Wiley-VCH), to which all invited speakers will be asked to contribute.

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09:00 Welcome    
 
Optics : Shahzada Ahmad, Carlo Ricci
09:15
Authors : Philippe F. Smet
Affiliations : LumiLab, Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, 9000 Gent (Belgium)

Resume : Two decades after the development of the blue light-emitting diode (LED), LEDs have quickly established themselves as the lighting technology of the future. The high efficiency, spectral tunability, lack of toxic compounds and a small footprint makes them far more attractive than other lighting technologies. The high efficiency, now well exceeding 100 lum/W in commercial products, has still the margin to double, promising a strong reduction in electricity consumption. White LEDs are commonly based on a blue LED, combined with luminescent materials, or phosphors, which convert part of the blue light to longer wavelengths, the mixture providing white light. Besides the workhorse Y3Al5O12:Ce (YAG:Ce, yielding yellow emission), europium doped phosphors are used to provide e.g. the red emission required for warm-white LEDs. Six main requirements for LED phosphors are discussed and used to explain the discrepancy between the high number of compositions described in literature and the handful of actually used compounds, being almost uniquely based on rare earth ions as luminescent center [1]. Alternative materials avoiding the use of rare earth ions are discussed, including Mn4+ doped fluorides phosphors (e.g. K2SiF6:Mn4+ [2]) and quantum dots. Finally, the impact of phosphor geometries on phosphor use, including remote phosphor applications, are discussed. [1] Smet PF and Joos JJ, Nat. Mater. 16 (2017) 500. [2] Sijbom H et al, Opt. Mater. Exp. 7 (2017) 3332.

C.1.1
09:45
Authors : Cedric Renaud a-b) , Manuel Lopes a-b), Suzanne Fery-Forgues c-d)
Affiliations : a) Université de Toulouse; UPS, INP; LAPLACE (Laboratoire Plasma et Conversion d’Energie), 118 route de Narbonne, F-31062 Toulouse, France b) CNRS; LAPLACE, F-31062 Toulouse, France c) CNRS, SPCMIB-UMR 5068, F31062 Toulouse, France d) CNRS, SPCMIB-UMR 5068, F31062 Toulouse, France

Resume : Two derivatives of mono- and bis-benzoxazole bearing a tert-butyl group (Bzx and BBzx, respectively) were used as emissive layer (EML) within organic light emitting diodes (OLED). They were chosen because of their efficient emission in the UV and deep blue spectral range with quantum efficiency up to 0.33 in the solid-state. The influence of steric hindrance of the chromophores on the electroluminescence (EL) properties has been shown. With passing from Bzx to BBzx, a shift of the emission from green to deep blue was observed. Emission was strongly related to the interaction between EML and electron transport layer (ETL). The studies show deep blue emission (at 421 nm) assigned to BBzx and the appearance of a blue emission band (at 475 nm) originating from ETL. These optical features specific to BBzx based devices are attributed to the modification of electronic states induced by the non-planar conformation of BBzx molecules in thin solid-films. Non-doped OLED displayed a deep blue emission at 421 nm with CIE coordinate of (0.157, 0.044) and a narrow FHWM of 45 nm in the EL spectra. An irradiance of 300 μW.cm−2 was achieved with a driving current of 100 mA/cm2. The color saturation of BBzx based devices was attributed to its twisted molecular structure leading to the reduction of the vibration splitting, and hence narrow EL spectra in the solid state. The results suggest that bis-benzoxazole molecules may be useful as an efficient color saturation deep-blue emitter in OLED.

C.1.2
10:00
Authors : Jung Hyeon Yoo1, Hyun Bin Kim1, Seung Hee Choi1, Seok Bin Kwon1, Seong Guk Jeong1, Young Hyun Song3 and Dae Ho Yoon1,2,*
Affiliations : 1 School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 16419, Korea. ; 2 SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SKKU), Suwon 440-746, Republic of Korea. ; 3Lighting Design & Component Research Center, Korea Photonics Technology Institute (KOPTI), Gwangju, 61007, Republic of Korea.

Resume : Cesium lead halide perovskite light emitting materials have attracted attention by these high color purity and stability. The narrow full width at half maximum (FWHM) and low cost of raw materials makes halide perovskite materials highly potential advanced materials for applications in light emitting diodes. Furthermore, low energy synthesis process and possibility of output product to be either solution or powder, adds to widespread applications. Extra-ordinary optical properties make halide perovskite favored materials for next generation lighting materials. In this study, CsPb(Br0.4, I0.6)3 was synthesized by hot injection method and blended with ethyl cellulose and poly-methylmetacrylate based films to generate warm white using with conventional inorganic YAG:Ce3+. Fabricated cesium lead halide perovskite films showed outstanding characteristics FWHM of 32nm and high luminous efficacy of 46.45 lm/W. We propose the CsPb(Br0.4, I0.6)3 perovskite QDs with ethyl cellulose as a promising red-emitting material and a color converter which can replace the conventional inorganic phosphor.

C.1.3
10:15
Authors : A. Armano (a,b,*), G. Buscarino (a), M. Cannas (a), F. M. Gelardi (a), F. Giannazzo (c), E. Schilirò (c), S. Agnello (a,*)
Affiliations : a) Department of Physics and Chemistry, University of Palermo, Via Archirafi 36, 90143 Palermo, Italy; b) Department of Physics and Astronomy, University of Catania, Via Santa Sofia 64, 95123 Catania, Italy; c) CNR-IMM, Strada VIII 5, 95121 Catania, Italy; *) Corresponding Author

Resume : Use of Graphene (Gr) in many optical and electronic devices is continuously growing due to its large transparency and high charge mobility. These features push for substitution of single layer Gr in transparent conductive layers and in the channel between source and drain of microelectronic devices. To this aim it is mandatory to determine the mechanical and electrical changes of Gr during its use as, for example, due to heating or reaction with atmosphere gases. Furthermore, the possibility to tune the charge carrier content and the Fermi level by opportune thermal treatments is foreseen for device realization. In this work, we study the Gr strain and p-doping effectiveness by thermal treatments up to 300°C in controlled atmosphere of N2, O2, CO2, H2O or vacuum by combining Raman Spectroscopy and Atomic Force Microscopy. The investigation is carried out by a time resolved procedure to highlight how the kinetics aspects affect the involved processes. It is found that doping is characterized by double rate kinetics as well as the de-doping effect induced by exposure to ambient atmosphere. These results are interpreted on the basis of two physical and chemical competing processes: molecular adsorption and red-ox reaction. A prominent role of gas is evidenced showing the largest effectiveness of doping by O2 and de-doping by H2O in gas phase as contrasted to liquid. Finally, the strain effect is dominant in inert atmosphere and strongly sensitive to the kinetics of treatment.

C.1.5
10:30 Coffee Break    
 
TCO & optolectronics 1 : Maria Luisa Grilli
11:15
Authors : Chaoyang Li; Qiang Zhang
Affiliations : Kochi University of Technology

Resume : The transparent and conductive AZO films were successfully prepared with the good electrical and optical properties comparable to commercial ITO substrates. It was found that the obtained metal oxide film not only contributed to be conductive film but also to the vertically alignment of ZnO nanorods during reducing annealing process, resulting in the high transmittance of the ZnO based photoanodes in DSSC. There are 4 steps for preparing the coated ZnO/ TiO2 core-shell nanorods. 1) Transparent and conductive Al-doped ZnO film was deposited on glass substrate by radio frequency magnetron sputtering. 2) The ZnO thin film was deposited on obtained AZO film. 3) The ZnO/AZO (500nm/300nm) double layer film was used to fabricate ZnO nanorods which were produced from recrystallization growth from as-deposited ZnO thin film in a multi-annealing process. 4) The anatase TiO2 thin layer was coated on the obtained ZnO nanorods by mist CVD method. The dye- sensitized solar cells were fabricated, in which the ZnO nanorods and TiO2 coated ZnO nanorods were respectively applied as photoanodes in DSSCs for comparison. As the results: Thickness of AZO films had a significant influence on the structural, electrical, and optical properties of AZO films. The good vertical alignment of the ZnO nanorods was significantly dependent on the crystallinity of AZO film. The pure anatase structured TiO2 thin films were successfully coated on ZnO nanorods with very good uniformity. The obtained ZnO/TiO2 core shell nanostructures significantly enhanced the overall conversion efficiency of the dye sensitized solar cells.

C.2.1
11:45
Authors : Rishi Dhawan, Emila Panda
Affiliations : Department of Materials Science and Engineering IIT Gandhinagar, Palaj, Gujarat-382355

Resume : Developing transparent conductors that can utilize a portion of the UV range of the sunlight to increase solar cell efficiency requires bandgap engineering by varying the process parameters as well as type and concentration of dopants in the host materials. To this end, ZnO is a desired material because of its wide direct band gap (Eg) of 3.3 eV, low cost and less toxicity. In this work, Al and/or Mg-doped ZnO films are prepared by varying a range of process parameters in RF magnetron sputtering. A detailed microstructural and optoelectronic characterization of all these films are then carried out by using a combination of experimental techniques, like, GI-XRD, AFM, FESEM, XPS, UV-Vis-NIR, PL spectroscopy and Hall effect measurement system. All these films are found to have high optical transparency (> 85% in the visible region). All these films show blue shift as a result of Mg and/or Al doping with Eg ranging from 3.5 to 4 eV. Moreover, (Al, Mg)-doped ZnO films are found to have better optoelectronic properties than those of ZnO films doped only using either Al or Mg. Whereas Mg is found to increase the overall transmittance of these films, Al addition is found to increase both the carrier concentration and carrier mobility, with the best values of the electrical properties being obtained when only Al is added to ZnO. This study shows a possible method to harness the near UV portion of the sunlight by doing bandgap engineering of ZnO through the addition of Al and/or Mg without compromising much on their overall electrical properties.

C.2.2
12:00
Authors : Chetan C. Singh and Emila Panda
Affiliations : Department of Materials Science and Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar 382355, Gujarat, India

Resume : In order to know the threshold quantity of the zinc interstitials that contributes in an increase in carrier concentration in the Al-doped ZnO (AZO) films and their effect on the overall microstructure and optoelectronic properties of these films, in this work, Zn-rich- AZO films are fabricated by adding excess zinc (from a zinc metallic target) during their deposition in RF magnetron sputtering and are then investigated using a wide range of experimental techniques. To understand fundamentally the role of zinc atoms in creating the electronic defect states and thereby tuning the overall microstructure and optoelectronic properties of these films, we conducted similar sets of experiments also with the ZnO films. The excessively introduced zinc in these AZO and/or ZnO films is found to increase the shallow donor level defects (i.e., zinc interstitials and oxygen-related electronic defect states), which is found to significantly increase the carrier concentration in these films. Additionally, aluminum is seen to enhance the creation of these electronic defect states in these films, thereby contributing more to the overall carrier concentration of these films. However, carrier mobility is found to decrease when carrier concentration values are higher than 4 ×10^20 cm^−3, because of the electron-electron scattering. Whereas, optical band gap for the ZnO films is found to increase with increasing carrier concentration because of the B-M shift, these decrease for the AZO films due to the band gap narrowing effect caused by excess carrier concentration.

C.2.3
12:15
Authors : Narendra Bandaru and Emila Panda
Affiliations : Department of Materials Science and Engineering, Indian Institute of Technology Gandhinagar, Palaj, 382355, Gujarat, India

Resume : A detailed understanding of the individual layers (i.e., absorber, buffer and/or contacts) is necessary to maintain as well as improve the device efficiency in a solar cell. Often a slight variation in the process condition varies the microstructure and thereby induced optoelectronic properties of these layers, hence significantly affecting the device performance. To this end, here varying thickness of the highly resistive ZnO buffer layer is deposited on Al-doped ZnO (AZO) coated soda lime glass (SLG) substrate by using RF magnetron sputtering and using two different process steps: process I, where ZnO layers are deposited on the AZO film immediately at the same substrate temperature (Ts) of 623 K and process II, where AZO-coated SLG is cooled to room temperature and reheated again to 623 K for ZnO deposition. A detailed microstructural and optoelectronic characterization of all these films are then carried out by using a wide range of experimental tools. All these bilayers are found to grow in ZnO hexagonal wurtzite structure with preferred (002) and (103) orientations and with an average transmittance of > 84% in the visible range. However, electrical resistivity decreased for the bilayers deposited in process II as compared to process I, due to an increase in carrier concentration because of enhancement in the shallow donor level defects (like, Zn interstitial, extended Zn interstitials and single charged oxygen vacancies) and carrier mobility due to improvement in the crystallite sizes, suggesting its enhanced suitability in CIGS thin film solar cells.

C.2.4
12:30 Lunch break    
 
Electro-chemical, -caloric, -mechanical : Roberto Iglesias, Patrice Miska
14:15
Authors : Jinwoo Lee
Affiliations : Department of Chemical Engineeering, Pohang University of Science and Technology

Resume : Lithium-sulfur (Li-S) batteries are regarded as potential high-energy storage devices due to their outstanding energy density. However, the low electrical conductivity of sulfur, dissolution of the active material, and sluggish reaction kinetics cause poor cycle stability and rate performance. A variety of approaches have been attempted to resolve the above issues and achieve enhanced electrochemical performance. However, inexpensive multifunctional host materials which can accommodate large quantities of sulfur and exhibit high electrode density are not widely available, which hinders the commercialization of Li-S batteries. Herein, mesoporous carbon microspheres with ultrahigh pore volume are synthesized, followed by the incorporation of Fe-N-C molecular catalysts into the mesopores, which can act as sulfur hosts. The ultrahigh pore volume of the prepared host material can accommodate up to ~87 wt.% sulfur while the uniformly controlled spherical morphology and particle size of the carbon microspheres enable high areal/volumetric capacity with high electrode density. Furthermore, the uniform distribution of Fe-N-C (only 0.33 wt.%) enhances the redox kinetics of conversion reaction of sulfur and decreases the overpotential. The resulting electrode with 5.2 mg sulfur per cm2 shows excellent cycle stability and 84% retention of the initial capacity even after 500 cycles at a 3 C rate.

C.3.1
14:45
Authors : Ghulam Ali, Kyung Yoon Chung
Affiliations : Center for Energy Convergence Research, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 02792, Republic of Korea

Resume : There is need to develop high-performance large-scale batteries for the intermittent energy sources. Sodium-ion batteries (SIBs) have emerged as a potential alternative to the lithium-ion batteries (LIBs), especially, for the use of electrical energy storage system (ESS). However, high-performance electrode materials are required for the realization of SIBs. Herein, a nanocomposite based on SnF2 and acetylene black is proposed as a high-performance anode material for SIBs. The SnF2@C electrode delivers a high reversible capacity of 563 mAh g-1 which is higher than the specific capacity of 323 mAh g-1 of the micron-sized bare SnF2 electrode. The reaction mechanism of high-performance SnF2@C is revealed by in-situ XRD, ex-situ XAS, and ex-situ TEM. The in-situ XRD results show the existence of a solid solution of two or more compositions during cycling. Ex-situ XAS reveals the electronic and atomic configurations of SnF2@C at different potential states during dis/charging. The results reveal that the valence change of Sn follows the conversion (SnF2 + 2Na → Sn + 2NaF) and alloying (Sn + XNa → SnNaX) reaction upon sodium insertion into a composite.

C.3.2
15:00
Authors : G. Suchaneck, G. Gerlach
Affiliations : TU Dresden, Solid State Electronics Laboratory, 01062 Dresden, Germany

Resume : Electrocaloric (EC) cooling is a promising future technology of large area refrigeration. Cooling power densities of a few W/cm2 and temperature spans in the order of 20 K (in regeneration systems) are achievable at a cycle time of 100 ms. Currently, relaxor (1-x)Pb(Mg1/3Nb2/3)O3 − xPbTiO3 (PMN-PT), x < 0.4, solid solutions are the most studied and best performing EC materials. On the other hand, the highest values of EC temperature change were obtained in lead-containing antiferroelectric thin films. Recently, also BaZrxTi1-xO3 (BZT) solid solutions came into the focus of EC research. However, their performance at high electric fields, E > 10 V/ µm, is still unknown. The relative efficiency of a refrigerant is defined as the ratio of the coefficient of performance (COP - the useful heating or cooling provided divided by the work required) to the COP of an ideal Carnot cycle. In this work, we demonstrate by Landau-Ginzburg-Devonshire calculations of the EC temperature change of BZT that it provides a similar EC performance as lead-containing materials at high electric fields E > 10 V/µm. An extrapolation of available experimental data to higher electric fields predicts for BZT EC temperature changes of up to 10-15 K suitable for commercial application. We estimate the relative refrigerant efficiency of lead-free, BaTiO3-based materials and demonstrate values of larger than 90% exceeding the ones of any other solid state cooling technology.

C.3.3
15:15
Authors : Wei-Ting WU, Chin-Shing KANG, Jing-Shiang SHIH, Chun-Chieh WANG, Chia-Min WEI
Affiliations : Casting Technology Section, Metal Processing R&D Department, Metal Industries Research & Development Centre; Casting Technology Section, Metal Processing R&D Department, Metal Industries Research & Development Centre; Department of Materials and Optoelectronic Science, National Sun Yat-sen University; Bioinformatics and Medical Engineering, Asia University

Resume : There are numerous high temperature stainless steels, which usually exhibit high creep strength, good resistance to isothermal, good resistance to cyclic oxidation, good resistance to combustion gases, good structural stability at high temperatures. Among the material properties, relatively low strength is the major issue of high temperature stainless steel, especially austenite phase stainless steel. However, the mechanical response of present high temperature stainless steel, 253 MA as example, should be further increased to meet the environmental requirement for the applications of waste heat recycling or high efficiency engine. In this study, the idea of precipitation hardening similar to duplex stainless steel is introduced to strengthen 253 MA. The Cr content is designed to raise in order to precipitate second phase at the grain boundary as the obstacle of dislocation propagation during the deformation at high temperature. The samples of the as-casted 253 MA and 253 MA with more Cr content are conducted tensile test both at room temperature and 900 oC. In the preliminary research results, both the yield stress and tensile strength at high temperature are increased significantly. And the relationship between the mechanical response and microstructure would be examined carefully and discussed in detail.

C.3.4
15:30
Authors : Mario Urso, Francesco Priolo, Salvo Mirabella
Affiliations : MATIS CNR-IMM and University of Catania, Physics and Astronomy Department, Via S. Sofia 64, 95123 Catania, Italy; MATIS CNR-IMM and University of Catania, Physics and Astronomy Department, Via S. Sofia 64, 95123 Catania, Italy; MATIS CNR-IMM and University of Catania, Physics and Astronomy Department, Via S. Sofia 64, 95123 Catania, Italy

Resume : In recent years Ni-based nanostructures have attracted great attention for electrochemical energy storage applications. In this work, we present a novel Ni nanostructure with a very high surface over volume ratio and with promising features in terms of specific capacitance and stability, if compared with the amount of critical raw material used (Ni). Scanning electron microscopy (SEM) reveals that the Ni nanostructure, grown by chemical bath deposition (CBD) followed by a reducing annealing, consists of an ensemble of interconnected Ni nanoparticles (20-30 nm in size). Cyclic voltammetry (CV) in alkaline solution is used to cover the Ni nanoparticles with an active layer of Ni(OH)2/NiOOH species. The supercapacitive behaviour of the Ni/Ni(OH)2 core-shell nanoparticles (called Ni/Ni(OH)2 nanofoam) is investigated by CV, electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge tests in 1 M KOH. Superior specific capacitance of 2253 F/g at 1 A/g is achieved by the Ni/Ni(OH)2 nanofoam, with a much higher cycling stability than the Ni(OH)2 nanosheets obtained with only CBD process. The enhancement of the supercapacitive properties is due to the metallic core of the Ni/Ni(OH)2 nanofoam, which improves the electric conductivity of the film, and to the better adhesion and stability of the film after the annealing process. This work offers a new strategy to enhance the energy storage performances of conventional Ni(OH)2-based electrodes, by reducing the amount of used Ni.

C.3.5
15:45 Coffee Break    
 
POSTER SESSION : Jose A. De Toro, Carlo Ricci, Patrice Miska
16:30
Authors : Uzawa Yuko, Tomohiko Nakajima, Muneyasu Suzuki, Iwao Yamaguchi, Tetsuo Tsuchiya,
Affiliations : National Institute of Advanced Industrial Science and Technology(AIST)

Resume : For the electronics, optical and solar cell applications, a transparent conductive thin film is very important material. So for, polycrystalline ITO material is commonly used for their applications because of low resistivity at low processing temperature by using the physical vapor process. However, as Indium is a rare metal, it is necessary to develop a Materials Substituting Rare Metals. Tin oxide is a promising material for next electronic devices because it offers good properties, such as high conductivity, transparency, and chemical stability. In addition, it is also an abundantly available natural resource. However, in most cases, the processes for Tin oxide growth require both vacuum and high temperature, making device production expensive. To decrease the processing temperature, we developed excimer laser-assisted metal organic deposition(ELAMOD). By using the ELAMOD, Sb-doped SnO2 (001) epitaxial film on a TiO2 (001) substrate and Polycrystalline SnO2 film was prepared. The effects of wavelength, shot number and Sb-doping content on the electrical properties such as resistivity, carrier concentration and mobility were investigated. The resistivity of the Sb-doped SnO2 (001) epitaxial film prepared by ArF laser was lower than that of the film prepared by KrF laser. The lowest resistivity of the Sb-doped SnO2 film prepared by ELAMOD with ArF laser was 2.5×10-3Ωcm, when the Sb-doping is 2%. By using the photo process, SnO2 film was formed at room temperature. In addition, Sb content can be reduced compared with thermal process. The difference in the optimum Sb doping concentration and resistivity between excimer laser assisted MOD process and thermal MOD process were discussed.

C.P.1
16:30
Authors : K. Kouno, T. Tsubata, Y. Uzawa, T. Nakajima, T. Tsuchiya
Affiliations : National Institute of Advanced Industrial Science and Technology (AIST)

Resume : Considering the recent global interest in reducing energy consumption, SiC power electronics technology is now ready to enable the step to the next plateau for efficiency standards. In most case, SiC power modules are designed to work at operating temperatures around 250 oC. Therefore, comical available electronic components such as resistor cannot use for the SiC modules because the electrode and resistor materials are deterioration in the temperature. In addition, we found that the trimming part is not good for the heat cycling properties (-40-250oC). Moreover, present resistor is made of the mixture of RuO2 and glass. So, development of the high heat resistant resistor without using the rare metal and glass composite would be desired for preventing the Resource depletion. In order to protect the environment and critical resources of the next generation society, it is necessary to construct an innovative alternative and circulation cycle of the main materials and components of green devices.Therefore, a development high heat resistant new electronic component such as resistor is necessary. Bi2Sr2CaCu2Oy is candidate materials for new high heat resistant resistor. In this paper, we investigated the effect of the La, Sm, Ce doping to Bi2Sr2CaCu2Oy on the resistance and temperature dependence of the resistance by using the MOD process. As a result, Bi2Sr2CaCu2Oy thin film resistor without glass was successfully obtained. The lowest resistance is 5Ω and the TCR is within 500ppm/K. Detailed results will be presented in the conference. This work was supported by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), "Next-generation power electronics/Consistent R&D of next-generation SiC power electronics" (funding agency: NEDO)

C.P.2
16:30
Authors : Tzu-Yuan Lee, Chi-Young Lee, Hsin-Tien Chiu
Affiliations : Department of Applied Chemistry, Nation Chiao Tung University, Hsinchu, Taiwan, 30010 R. O. C.

Resume : In this experiment, we invented a new synthetic way to synthesize anatase phase TiO2 with {001}/{101} coexposed facets by vapor-solid reaction growth (VSRG) method. In the synthesis process change the HF to the TiCl4 can also be synthesized {001} facets. Not at all, we use the Cl-containing agents more environmentally friendly than F-containing agents. These synthesis are not reported in the literature. In the synthesis process, we control the temperature and concentration of TiCl4 to find the best condition TiO2. Finally, the best condition product VT923 length and thickness about 400 nm and 200 nm. And we found the T923 powder to be pale blue, we speculated that the powder contains some oxygen defect. So we will use the TGA, XPS and EPR to confirm that the product contains the defect. Afterward the TiO2 will do the photocatalytic test in the methylene blue (MB) photodegradation under UV-vis light. We will discuss the results of the experiment and find the cause. Herein, we report the photocatalytic photodegradation of methylene blue (MB) over anatase TiO2 with {001}/{101} coexposed facets and the effect of the ratio of these facets on the emission reduction process. Finally, VT923 with {001}/{101} ratio close to one which exhibits outstanding photocatalytic performance on MB. It was found that the surface area of P25 standard (46.84 m2/g) was about 12 times of VT923(4.20 m2/g). But the VT923 of degradation rate constant k (0.052 min-1) is similar to P25 (0.05771 min-1).

C.P.3
16:30
Authors : V. Tucureanuă [1,2], A. Matei [1], A. Avram [1], I. Mihalache [1], M.C.Popescu [1], C. Romanițan [1], B.C. Tincu [1,3], M. Avram [1], C.V. Marculescu [1], T. Burinaru [1,4], D. Munteanu [2]
Affiliations : 1National Institute for Research and Development in Microtehnologies (IMT-Bucharest), [1] Erou Iancu Nicolae Street, 126A, 077190, Bucharest, Romania; [2] Transilvania University of Brasov, Department of Materials Science,29 Eroilor Blvd, 500036, Brasov, Romania; [3] University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science, 1-7 Polizu, 011061 Bucharest, Romania; [4] University Of Agronomic Sciences And Veterinary Medicine Of Bucharest, Faculty Of Veterinary Medicine, Anatomic Pathology Department, Splaiul Independentei 105 Sector 5 050097 Bucharest, Romania

Resume : Fluorescent and luminescent materials, such as yttrium aluminum garnet doped with different metal ions (rare earths or transition metals), have found applicability in various fields, from optoelectronics (i.e.: lighting systems, LCDs, CRTs, lasers) to aerospace (i.e: thermal barriers) and biotechnological applications (i.e.: fluorescence marker, contrast agent in medical imaging, imaging screens, drug delivery etc). For the development of these types of materials, the necessity of surface modification appeared in order to avoid the agglomeration tendency, to increase the optical efficiency and to attach different biomolecules. This paper describes a method of preparing the precursor of cerium doped yttrium aluminum garnet (YAG:Ce) followed by heat treatment at 1100°C and surface modification by decorating with gold nanoparticles. The quality and composition of YAG:Ce and YAG:Ce decorated with gold nanoparticles was confirmed by Fourier Transform Infrared (FTIR) spectrometry, scanning electron microscopy (SEM), x-ray diffraction (XRD), and photoluminescence (PL) spectroscopy. FTIR spectrometry confirms the formation of M-O bonds and the transition from amorphous to crystalline state. XRD revealed both the formation of the pure garnet phase and the presence of gold nanoparticles. SEM has highlighted a reduced agglomeration tendency for modified phosphors. PL spectroscopy shows an improvement in optical properties probably due to the improvement of the morphological properties. The obtained results indicate the YAG:Ce modified with gold nanoparticle to be a very good material for applications in optoelectronics, but also for other areas such as biotechnology or aerospace.

C.P.4
16:30
Authors : Ivo M. Pinatti (1), Paula F. S. Pereira (2), Elson Longo (1) and Ieda L. V. Rosa (1)
Affiliations : (1) INCTMN, Federal University of Sao Carlos (UFSCar), Chemistry Department, São Carlos, SP, Brazil. (2) INCTMN, State University of São Paulo (UNESP),Chemistry Institute, Araraquara, SP, Brazil.

Resume : Metal Tungstates have been extensively studied due to their outstanding properties which permits be employed in various fields, including phosphors, laser, catalysis and other functional materials based on their electronic, optical, and chemical characteristics. Silver Tungstate is an example of this class of materials which has many applications due to its photoluminescent and photocatalytic properties. Emission bands of Rare Earth (RE) ions are easy to study in the visible region due to the structure of the energy levels, such as fine lines of absorption and emission. Rare Earth (RE = Pr, Sm, Eu, Tb, Dy and Tm) doped Silver Tungstate (α-Ag2WO4:RE3 ) powders were synthesized by the coprecipitation method at 90 °C for 30 minutes. X-ray diffraction presented a single phase indexed as orthorhombic structure with space group Pn2n. The emission spectra showed the characteristic RE transitions in the visible region of electromagnetic spectrum. The color coordinates of the system were evaluated and plotted on a standard CIE index diagram. Micro-Raman were used to analyze the degree of structural order−disorder at short-range and revealed the presence of at least 14 high intensity Raman-active vibrational modes. The FE-SEM micrograph showed hexagonal rod-like α-Ag2WO4 microcrystals with agglomerate nature and average length of 1 μm and width of 90 nm. These results show possible application of these phosphors in new optical devices.

C.P.5
16:30
Authors : Hayong Song, Moon-Ho Ham
Affiliations : School of Materials Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea

Resume : Tin oxide is expected as one of the most promising anode materials for lithium ion batteries (LIBs) because of its high theoretical capacity. However, SnO2 has low conductivity and undergoes pulverization resulted from large volume changes during charge/discharge processes, which lead to rapid decline in the performance. These problems can be solved by doping heteroatom to SnO2 and by introducing conductive carbon materials. In this study, we synthesized hybrid composites composed of size-controlled Co-doped SnO2 nanoparticles (NPs) covered with thin carbon shell and reduced graphite oxide (RGO). The doping of Co to SnO2 effectively enhanced the conductivity of SnO2 by introducing oxygen vacancies. Furthermore, carbon materials act as an electron pathway and a structural buffer to accommodate the volume change. The Co-doped SnO2@C/RGO composites showed the improved reversible capacity of ~1100 mAh/g with more stable cycle durability, compared to those of undoped SnO2/RGO and SnO2@C/RGO composites. These results demonstrate that this structural design can be the key strategy to improve the electrochemical properties of metal oxides and their composites in LIBs.

C.P.6
16:30
Authors : Ji-Eun Lee1) , Seong Jun Kang2),Han-Ki Kim1)*
Affiliations : 1) School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon, Kyunggi-do 16419, Republic of Korea 2) Department of Advanced Materials Engineering for Information and Electronics, Kyung Hee University, 1 Seocheon-dong, Yongin-si, Gyeonggi-do 446-701, South Korea

Resume : Flexible and transparent electrodes with a high transmittance, a low resistivity, and an outstanding mechanical flexibility are one of the key components for high-quality flexible quantum dots light emitting diodes (QDLEDs) because performance and lifetime of QDLEDs are closely related to the electrical, optical, and mechanical properties of transparent and flexible electrodes. Although sputtered Sn-doped In2O3 (ITO) films have mainly been used as electrodes for QDLEDs, their poor flexibility, high resistivity and high process temperature have been considered as critical problems. To solve the problems of the sputtered ITO films, in this work, we suggested the flexible W-doped In2O3 (IWO) films prepared by vertical in-line ion plating system on PET substrate at room temperature. The optimized IWO electrodes showed a sheet resistance of 33.47 Ohm/square, an average transmittance of 90.56 % at visible range (400 nm~800 nm) and work function of 4.85 eV. Based on specially designed inner/outer bending, twisting, rolling, and folding testers, we examined the mechanical properties of the ion plated IWO/PET samples in detail. The IWO electrode films had a constant resistance change (ᅀR/R0) within an outer bending radius of 5 mm, which is acceptable in fabrication of flexible QDLEDs. To show the feasibility of ion plated IWO films as flexible electrode for QDLEDs, we fabricated typical QDLED on the ion plated IWO and sputtered ITO electrodes, simultaneously. Maximum luminance and current efficiency of QDLEDs with ion plated IWO electrodes were better than those of QDLED with reference ITO electrode. Better performance of QDLED with IWO electrodes indicates that the ion-plated IWO film is a promising transparent and flexible electrode substituting conventional ITO films for high performance flexible QDLEDs.

C.P.7
16:30
Authors : C.F. Ciobota1 , A.Sobetkii 1, R.R.Piticescu 1 , Antonio Rinaldi 2, Daniele Valerini 2
Affiliations : 1- National R&D Institute for Nonferrous and Rare Metals, Pantelimon, Ilfov, Romania 2- ENEA, Cassacia Research Centre, Rome, Italy

Resume : Functionally graded materials (FGM) are modern solutions to replace critical raw materials in high temperature/high corrosion applications. The use of novel ceramic films increase the working temperature up to 1600 °C. The paper presents some original results regarding the development of multi-layered zirconia-based films on different substrates, including Nimonic (reference) and graphite. Coatings were obtained using an unique electron beam installation (Torr Int., USA), endowed with 5 e-guns having a 4 crucibles carousel and 5 separate high voltage power supplies with 10KW each, was used to obtain combinatorial coatings of microns on Nimonic and graphite substrates. During deposition process the substrates were heated at 500 °C. The morphology, chemical composition and topography of the coatings were analyzed using High - Resolution Scanning Electron Microscopy (HR-SEM), Energy-dispersive X-ray spectroscopy (EDX), Atomic Force Microscopy (AFM).

C.P.8
16:30
Authors : D. Louloudakis1 2 3*, W. Thongpan4, K. Mouratis3 5, E. Koudoumas3 6, G. Kiriakidis1 7, P. Singjai2
Affiliations : 1Institute of Electronic Structure and Laser, Foundation for Research & Technology- Hellas, P.O. Box 1527, Vassilika Vouton, 711 10 Heraklion, Crete, Greece; 2Center of Excellence for Physics and Astronomy, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; 3Center of Materials Technology and Photonics, School of Engineering, Technological Educational Institute of Crete, 710 04 Heraklion, Crete, Greece; 4Graduate School Chiang Mai, PhD’s Degree Program in Applied Physics, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand; 5Department of Physics, University of Patras, Patras, 26504, Greece; 6Department of Electrical Engineering, School of Engineering, Technological Educational Institute of Crete, 710 04 Heraklion, Crete, Greece; 7Department of Physics, University of Crete 711 00 Heraklion, Crete, Greece

Resume : During the last decades, depositions with reversible properties have attracted the scientific interest because of the large number of technological applications that they can be used, such as sensors, detectors, switches and smart windows. Electrochromic coatings, such as tungsten trioxide (WO3), have the ability to change their optical properties in the presence of a small electric potential difference, a property essential for the construction of energy efficient windows. Many methods, such as sol-gel, hydrothermal synthesis, rf-sputtering and chemical vapor deposition, have been used for the deposition of WO3. In this work, WO3 coatings were grown on Indium Tin Oxide glass substrates using tungsten wire as precursor for a range of deposition periods and annealing temperatures using a homemade spark machine. The deposition with the best performance was chosen in order to study the effect of the insertion of different kind and amounts of doping (such as Ag, Ni, Ti and V). The coatings were characterized by X-ray diffraction, UV/IR transmittance spectrophotometer, Raman spectroscopy, scanning electron microscopy and cyclic voltammetry. The role of different kind and amounts of doping in the crystalline monoclinic WO3 on the basic characteristics and electrochromic performance, including durability, time response, charge density and coloration efficiency, is discussed.

C.P.9
16:30
Authors : Chao-Wu Chu, Min-Chiao Tsai, Ni-Yun Hsieh, Ying-Ru Chen, Cheng-Han Chiang, Hsin-Tien Chiu and Chi-Young Lee
Affiliations : Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan; Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan

Resume : Amorphous TiO2 spheres with sizes ranging from submicroscale to microscale were synthesized by sol-gel process of titanium isopropoxide (TTIP) with octanoic acids. Based on Mie scattering theory, microspheres with diameter about 1 μm scatter near-infrared (NIR) selectively, resulting in thermo-temperature reduction, which leads to significantly improved insulation properties. In this work, amorphous TiO2 spheres were fabricated and applied to thermal insulation coating materials. With spreading amorphous TiO2 microspheres (diameter ~ 1.3 μm) and commercial TiO2 P25 on glass, the heat insulation performance was examined by UV-Vis-NIR spectrum. The results show that the optical transmittances in near-infrared and visible light region are 40% and 50% respectively for TiO2 microsphere coated glass, whereas, for commercial TiO2 P25 coated glass are 75% and 60% respectively, which indicate the heat insulation performance of TiO2 microsphere is better than that of commercial TiO2 P25. Furthermore, heat shielding test revealed different temperature between amorphous TiO2 microspheres and P25 (38°C and 40°C) after heating from 20°C for 1 hour continuously. According to these results, amorphous TiO2 microspheres could be a promising thermal insulation material to improve indoor thermal environment effectively.

C.P.10
16:30
Authors : Seong Guk Jeong, Seok Bin Kwon, Seung Hee Choi, Jung Hyeon Yoo, Hyun Bin Kim, Young Hyun Song, Dae Ho Yoon
Affiliations : School of Advanced Materials Science and Engineering, SungKyunKwan University, Suwon 440-746, Republic of Korea SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SKKU), Suwon 440-746, Republic of Korea Lighting Design & Component Research Center, Korea Photonics Technology Institute (KOPTI), Gwangju, 61007, Republic of Korea

Resume : Solid-state lighting based on phosphor converted white-emitting diodes has gained considerable attention as a replacement for conventional incandescent and fluorescent light sources due to their advantages compared with their conventional counterparts, such as luminous efficiency, lower energy consumption, diversity of packaging forms, long operating lifetime, and environmental safety. The YAG:Ce3+ can be applied in various forms such as phosphor in resins, the phosphor in silicone and phosphor in the glass, but these are not thermally stable. On the other hand, polycrystalline phosphors have an advantage of good thermal stability. Therefore, studies on polycrystalline phosphors are under way. YAG:Ce3+ ceramic phosphor plate (CPP) improved both yellow-ring phenomenon and the light-extraction efficiency Because of Al2O3 particle embedded in the cubic YAG:Ce3+ CPP as the second phase. Also, the Al2O3 particle has a birefringence effect due to its hexagonal structure, and its scattering of the light reduces the yellow-ring effect. In this study, we prepared YAG:Ce3+ CPP with various amounts of Al2O3. The characteristics were investigated according to the addition amount of Al2O3 and optimized. The luminous properties of the YAG:Ce3+ and Al2O3 are improved when compared to the YAG:Ce3+ alone, and hence, the luminous emittance, luminous flux, and conversion efficiency are improved. We suggest that CPP is a next-generation material for solid-state laser lighting in automotive applications.

C.P.11
16:30
Authors : Xuming Yang, Andrey L. Rogach*
Affiliations : Department of Materials Science and Engineering, and Center for Functional Photonics (CFP), City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong S.A.R. E-mail: andreyrogach@cityu.edu.hk

Resume : We have developed a vacuum calcination approach to fabricate selenium/carbon composites, which does not require intensive mixing and durable heating such as in commonly used melt-infusion methods of loading selenium into carbon hosts. Starting from carbon-coated selenium wires prepared via a wet-chemical reaction, selenium/carbon tubes are fabricated by a straightforward calcination process. The calcination is conducted in a confined space to produce the insulating carbon shell under vacuum, and selenium melts but remains a constituting part of the composite. Paired with sodium metal anode, the resultant selenium/carbon tubes deliver a high reversible capacity of 601 and 509 mAh g-1 at 0.2 and 2 C normalized by the mass of selenium, which corresponds to energy and power densities of 860 and 667 Wh kg-1 at 193 and 1770 W kg-1, respectively. Such capacity and rate performance surpasses most typical cathode materials for lithium or sodium (ion) batteries, according to the comparative literature analysis. Moreover, the robust tubular-like hollow structure of the selenium/carbon composites ensures for an impressive capacity retention of more than 90% after 1000 cycles at 20 C.

C.P.12
16:30
Authors : Alessia Amato1, Maria Letizia Ruello2, Francesca Beolchini1.
Affiliations : 1Università Politecnica delle Marche, DISVA, Ancona, Italy 2Università Politecnica of Marche, SIMAU, Ancona, Italy

Resume : The recent attention for the environmental issue has pushed the conversion of traditional systems of energy production with more sustainable strategies, involving renewable resources. In this context, the use of photovoltaic panels for the electricity generation has rapidly grown with the consequent development of several technologies, suitable for different applications. Considering the number of the already installed panels and its expected increase, a consequent huge quantity of end-of-life photovoltaic panel will be produced within a few years. Therefore, an efficient system of waste management should be planned, involving innovative recycling processes. Indeed, the panels composition, rich in valuable fractions, makes them a potential source of secondary raw materials. Particular attention focused on the CIGS (Cu(In, Ga)Se2) thin film solar cell, for the content of Ga and In, classified as critical raw materials by European Commission. The implementation of a leaching, ensured an In extraction higher than 65% and 90%, using a citric acid and sulfuric acid solution, respectively. On the other hand, considering the need for an additional agent for Ga mobilization, hydrogen peroxide and potassium permanganate were tested, with a final efficiency higher than 90%. Nevertheless, considering the possible environmental load due to these agents, further experiments took into account low impact options (e.g. glucose), assessing their sustainability by a life cycle approach

C.P.13
16:30
Authors : Figen KADIRGAN, Kadir KIRAN, Ozge ERSAHIN, Ozlem UCEL
Affiliations : Nano Science and Nanotechnology Program, Istanbul Technical University, Istanbul, Turkey

Resume : Catalytic converters are the devices used for purification of exhaust gases of automobile engines, which allow the simultaneous conversion of harmful gases into harmless ones. In these converters, the platinum group metals (PGMs) such as Pd, Pt and Rh are commonly used due to their high catalytic activities. However, it is important to recover the platinum group metals from industrial wastes because of many concerns around the world. In addition to rising demand of the use of these elements in many industrial areas, they have rare reserves on earth. Also, there is some difficulties in their mining process. Among platinum group metals, palladium is one of the elements that have the most efficient recovery rate. In the light of these informations, it can be suggested that scarcity of palladium can be reduced by the efficient recovery of palladium. In this study, Pd deposited on ceramic carrier from spent automobile catalyst has recovered by chemical and electrochemical methods. The amount of recovered Pd material was measured using spectroscopic methods.

C.P.14
16:30
Authors : Barbara Lasio1, Francesco Torre1, Roberto Orrù1, Giacomo Cao1, Marcello Cabibbo2, Francesco Delogu1
Affiliations : 1 Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali, Università degli Studi di Cagliari, via Marengo 2, 09123 Cagliari, Italy 2 Dipartimento di Meccanica, Università Politecnica delle Marche, via Brecce Bianche, 60131 Ancona, Italy

Resume : Metal matrix composites (MMCs) consist of the heterogeneous combination of two or more constituents [1]. Although the individual constituents maintain their distinct physical and chemical nature, the dispersion of materials to various extents and at different length scales can result in enhanced properties and performances compared to those exhibited separately by the constituents [2, 3]. Hence, MMCs represent an important case study for meeting the demand of replacing critical raw materials in future technology. In this contest, the present work deals with the fabrication of copper-graphene MMCs for structural applications. A fine dispersion of the filler has been achieved through two different approaches, top-down and bottom-up, respectively. Concerning the former, we started from graphite and copper microstructured powders inducing, through high energy ball milling, the mutual dispersion by reducing the dimensions of the components up to the nanometer scale [4]. On the other hand, the latter was based on a water-based redox reaction of a copper precursor on the surface of graphene to build up a nanometric composite [5]. In both cases, the obtained powders have been consolidated by spark plasma sintering and the obtained pellets subjected to nanoindentation in order to compare the mechanical properties related to the two different fabrication methods. [1] J.W. Kaczmar et al. 2000, Journal of Materials Processing Technology, 106, 58-67. [2] F. Delogu et al. 2017, Progress in Materials Science, 86 Pp 75-126. [3] L.Y. Chen et al. 2015, Nature, 528 Pp. 539-549. [4] P. Baláž et al. 2013, Chemical Society Reviews, 42, 7571-7637. [5] Q. Liu et al. 2012, Transactions of Nonferrous Metals Society of China, 22, 2198-2203.

C.P.15
16:30
Authors : S. Porcu1 , A. Cocco2, , A. Luridiana2, CM.Carbonaro1, R, Corpino1, D. Chiriu1, F. Secci2, P.C. Ricci1
Affiliations : 1 Dipartimento di Fisica, sp. N8 Km 0.700, Monserrato, CA, 09042 Italy 2 Dipartimento di Scienze Chimiche e Geologiche, sp. N8 Km 0.700, Monserrato, CA, 09042 Italy

Resume : The research on Rare Earth (RE) based materials is steadily active in order to realize new devices for photonic and optoelectronic applications requiring efficient light absorption, low losses of energy, and high quantum yield (QY) emission. Melamine (C3H6N6) is an organic compound known to have a strong absorption in UV region and an efficient emission at 356 nm, with a long tail extending in the blue range, mainly originated by triplet ground state recombination. This compound has been already utilized as organic ligand at the surfaces because to achieve of the so-called “antenna effect”. In this phenomenon the absorbed light is efficiently transferred to an emitting ion, strongly increasing the emitting quantum yield of the luminescent ion in the inorganic matrix. Herein we report the antenna effect on two hybrid systems obtained from scraps of wasted displays: Ce:YAG and Tb:Eu:Y2O3. The wide blue emission of the Ce in the YAG matrix and the green (550 nm, Tb) and red (610 nm Eu) in yttria, have been increased up to 200 times with respect to the powders without the external shell of melamine. Structural and morphologies measurements (NMR, XRD, Raman, SEM images), as well optical characterization (time resolved and steady time luminescence, absorption, excitation spectra) will be provided and discussed. This work aims to point out a new strategy for a virtuous recycling of the rare earths, giving a new life to wasted phosphors.

C.P.16
16:30
Authors : Rossella Delpiano (2), Pier Carlo Ricci (1), , Riccardo Corpino (1), Daniele Chiriu (1), Andrea Salis (2), Maria Francesca Casula (2), Carlo Maria Carbonaro (1).
Affiliations : 1 Department of Physics, University of Cagliari, Campus of Monserrato, sp n8, km 0.700, Monserrato, Italy 2 Department of Chemical and Geological Sciences and INSTM, University of Cagliari, Campus of Monserrato, sp n8, km 0.700, Monserrato, Italy

Resume : The photoluminescence (PL) properties of silica based nanostructured systems gathered large interest for the possible applications in optoelectronic devices, for example as efficient inorganic blue phosphor or as a probe of the structural properties of the insulating layer. The UV and blue PL emission of mesoporous silica are two broad bands whose quantum efficiency (up to 20−30%) boosted the research for photonics applications. Scaling down to nanometric dimensions induces a large increase of the surface-to-volume ratio and a number of surface defect centers are set at the silica surface. The promising emission properties are ascribed to these defects whose formation relies on silane chemistry and silica surface hydroxylation. However, the experimental data reported in the literature are sometimes contradictory, concerning, for example, the environment effects upon the optical properties or their relationship with the synthesis conditions. This is partly due to the heterogeneity of nanosized silica investigated. To further study the dependence of the blue and UV band on the surface texture, in the present work we examine the structural and optical properties of a large set of mesoporous silica, with both ordered and disordered porous network, prepared via templated sol-gel synthesis.

C.P.17
16:30
Authors : P. Camarda, L. Vaccaro, F. Messina, G. Buscarino, S. Agnello, F.M. Gelardi, M. Cannas
Affiliations : Department of Physics and Chemistry, University of Palermo, Italy

Resume : High efficiency and color tunability are properties of paramount importance for lighting applications in modern nanotechnologies (bioimaging, optoelectronics, and photovoltaics). ZnO is a material of choice for this purpose since it emits different visible bands associated with point defects in the network. On the other hand, its non-toxicity is crucial for the use in optical and/or electrical devices free from raw materials. Research is therefore active towards the development of synthesis methods which can finely control the physical and chemical characteristics of nanostructured ZnO thus tailoring its optical properties. In this work, we synthetize ZnO nanoparticles by pulsed laser ablation (PLA): two laser sources, ns Nd:YAG (1064 nm) and fs Ti:Sapphire (800 nm), are used to irradiate a Zn target in deionized water. Time-resolved spectra acquired under a tunable laser excitation allow to observe emission bands that are excited by band-to-band transition: UV, peaked at 3.3 eV and decaying in a sub-ns timescale, is due to the excitonic recombination; Green, centered at 2.3 eV and decaying in µs-ms timescale, is associated with oxygen vacancies; Blue, centered at 2.8 eV and decaying in ns, is peculiar to ZnO produced by fs PLAL, its origin being unclear yet. These results are promising in view to the realization of multi-color ZnO nanosystems thus increasing their use in lighting technologies.

C.P.18
16:30
Authors : Nils Steinbrück, Dr. Patrick Wenderoth, Prof. Dr. Guido Kickelbick
Affiliations : Saarland University, Inorganic Solid State Chemistry, Campus C4 1, 66123 Saarbrücken, Germany

Resume : Conventional conversion dyes in white light LED applications consist of inorganic oxides doped with rare earth ions. Organic dyes are potential candidates for reduction or even complete substitution of rare earth elements in LED devices. However, organic dyes are much more sensitive towards decomposition under the light/temperature impact in typical LED applications. In addition they show a strong sensitivity with regard to the chemical composition of the matrix they are embedded in. Therefore currently only so called remote applications are possible where the dye is placed in a matrix far away from the blue light emitting semiconductor. In this report we systematically investigated typical parameters that influence the lifetime of organic conversion dyes in LED applications. One of the major parameters is the matrix. We were able to show that a good distribution of the dye in the matrix is a crucial prerequisite for the lifetime of LED devices. In addition the barrier properties with regard to moisture and oxygen have to be tailored to increase the stability of the organic dyes. Particularly hybrid materials offer here many opportunities.

C.P.19
16:30
Authors : Paula F. S. Pereira†, Amanda F. Gouveia†, Camila C. de Foggi†, Ivo M. Pinatti†, Verónica Puerto§, Gladys Mínguez-Veja§, Héctor B. Mir§, Eloisa C. Cordoncillo§, Rosa Llusar§, Juan Andrés§ and Elson Longo†
Affiliations : †CDMF, LIEC, Chemistry Department of the Federal University of São Carlos (UFSCar), P.O. Box 676, 13565-905 São Carlos, SP, Brazil §Department of Analytical and Physical Chemistry, University Jaume I (UJI), Castelló 12071, Spain

Resume : Femtosecond lasers have been widely studied for micro- and nano-fabrication processes. Pulsed laser ablation in liquid has become a promising method to produce metallic nanoparticles and has been described in previous works1-3. In this work, Ag and Cu nanoparticles have been synthesized via laser ablation mediated by chitosan, a glucosamine polysaccharide. FE-SEM images revealed that the synthesis of these nanoparticles via laser irradiation and mediated by chitosan affected the shape and size distribution of the nanoparticles. X-ray diffraction pattern data indicated that all the samples obtained by laser ablation presented orthorhombic structures with peaks indicative of Ag and Cu metal nanoparticles. MR and FT-IR analysis confirmed characteristics of orthorhombic structures and bands characteristics of Ag and Cu metals were observed. HR-TEM images of the sample obtained after laser irradiation confirmed formation of Ag and Cu metallic nanoparticles. The Ag and Cu nanoparticles showed a higher efficiency in bactericidal activities against E. coli, S. aureus and C. albicans compared to Ag and Cu metallic nanoparticles obtained without chitosan mediation. These results show promise of application of these nanoparticles as a therapeutic. 1P. F. S. Pereira, C. C. Santos, A. F. Gouveia, M. M. Ferrer, I. M. Pinatti, G. Botelho, J. R. Sambrano, I. L. V. Rosa, J. Andrés, and E. Longo. Inorg. Chem., 2017, 56, 7360−7372 2P. H. D. Ferreira; M. G. Vivas; L. DE Boni; D. S. Dos Santos JR.; D. T. Balogh; L. Misoguti, C. R. Mendonca. Optics Express, 2011, 20, 518-523. 3A. Ancona, M. C. Sportelli, A. Trapani, R. A. Picca, C. Palazzo, E. Bonerba, F. P. Mezzapesa, G. Tantillo, G. Trapani, N. Cioffi. Materials Letters, 2014, 136, 397-400.

C.P.20
16:30
Authors : A. Cocco1, S. Porcu2, A. Luridiana1,C.M. Carbonaro2, P.C. Ricci2, F. Secci1,
Affiliations : 1 Dipartimento di Scienze Chimiche e Geologiche, sp. N8 Km 0.700, Monserrato, CA, 09042 Italy 2 Dipartimento di Fisica, sp. N8 Km 0.700, Monserrato, CA, 09042 Italy

Resume : Inorganic fluorescent materials are mostly based on the exploitation of Rare Earth Elements (REEs) that are in the list of Critical Raw Materials (CRM) since the first report in 2010. The development of new CRM free phosphors that are cost effective and with improved quantum efficiency and color quality is of highest priority for the next development of the lighting sector (displays, solid state lighting devices, photonic). In this framework we present new types of organic compounds that possess high thermal stability and low photodegradation. In particular a series of differently functionalized coumarins have been obtained through eco-compatible synthesis processes easy scalable. In particular, the engineering of the benzopyranic unit has allowed obtaining highly efficient coumarins in terms of fluorescence quantum yield and tunable emission spectrum by varying the electron donor group. Absorption and emission properties, decay kinetics, obtained by means of time resolved measurements in the sub-nanosecond time window, as well as thermal and photostability test permit to propose this class of organic compound as suitable for intriguing phosphors totally free of Critical Raw Materials.

C.P.21
16:30
Authors : A. I. Popov (1), E. Elsts (1), E. Shablonin (2) , E. Vasil'chenko (2), A. Ch.Lushchik (2) V. Kuzovkov (1), M. Ķemere (1), L. Trinkler (1) , and J. E. Munoz Santiuste (3)
Affiliations : (1) Institute of Solid State Physics, University of Latvia; (2) Institute of Physics, University of Tartu, (3) Departamento de Física, Escuela Politécnica Superior, Universidad Carlos III de Madrid, Leganés, Madrid, Spain

Resume : The results of the thermostimulated luminescence measurements, performed between 300 and 720°K of the stored energy in Y3Al5O12 and Gd3Ga5O12 single crystals, irradiated by fast neutrons with fluences of 2.1 x 1017 or 2.18 x 1019 n/cm2 or 1.8 MeV electrons, or thermochemically reduced will be reported and compared with previously published data. A clear pronounced dose effect was found and analyzed. In particular, four TSL peaks were observed in Y3Al5O12 samples subjected 2.18 x 1019 n/cm2, while in sample subjected 2.16 x 1017 , only three TSL peaks were detected. A comprehensive kinetic analysis of the glow peaks in Y3Al5O12 is performed. As usual, each TSL peak is characterized by the appropriate activation energis, which both crystals are 0.8 – 1.3 eV. The obtained values are compared with the appropriate activation energies for F-type center thermal annealing. Furthermore, we have also performed a comparative analysis of the photoluminescence properties of a series of neutron-irradiated and non-irradiated Y3Al5O12 single crystals. Finally, a laser-induced F ---> F+ color center photoconversion was examined and characterized as well.

C.P.22
16:30
Authors : Aleandro Antidormi 1, Claudio Melis 1, Enric Canadell 2, Luciano Colombo 1
Affiliations : 1 Dipartimento di Fisica, Università di Cagliari, Cittadella Universitaria, I-09042 Monserrato, Cagliari, Italy;2 Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de Bellaterra, 08193 Bellaterra, Barcelona, Spain

Resume : Among the possible applications of eumelanin (biolelectronics, biointerfaces, etc.), photovoltaics is a promising field which could highly benefit from its intrinsic features (broadband UV–vis absorption, etc.), with such a pigment employed as photoactive layer in hybrid solar cells. The envisioned application poses the need for a careful theoretical analysis on the adhesion properties of eumelanin on a substrate and the characterization of the hybrid system electronic features. In this work, we investigate a eumelanin/Si interface, where Si plays the role of inorganic layer. By means of ab initio calculations, we study the feasibility of the experimental formation process of eumelanin protomolecular structures in methanol ambient, evaluating the corresponding formation energy. Then, we explore the adhesion properties of eumelanin molecules on a silicon surface and extract the electronic structure of the resulting system. The corresponding band alignment is then used to address the overall photoconversion efficiency. Adopting the scheme of chemical disorder, which has been proved to successfully capture the variety of eumelanin protomolecules, we show that (1) the formation process of eumelanin protomolecules from the constituting monomers is generally hindered in a solvent environment with respect to vacuum and (2) key factors in improving the adhesion properties and band lineup of the molecules on an inorganic interface are the molecular electronic state and the planarity of their structures. Protomolecular models with a large number of nonterminated oxygen atoms and endowed with an intrinsically planar character tend to bind more strongly to the surface. In addition, they are more likely to produce a favorable band alignment for photoconversion applications.

C.P.23
16:30
Authors : K. Kacha1, F. Djeffal 1,2,* and A. Benhaya1
Affiliations : 1LEPCM, Department of Physics, University of Batna 1, Batna 05000, Algeria. 1LEA, Department of Electronics, University Mostefa Benboulaid-Batna 2, Batna 05000, Algeria. *E-mail: faycal.djeffal@univ-batna.dz, faycaldzdz@hotmail.com, Tel/Fax: 0021333805494

Resume : The Schottky junction-based technology is largely used elsewhere in the Si based power devices and photodetectors but is very new to the Au/ITO/Si photovoltaic technology. In this context, in this paper a new Figure of Merit (FoM) parameter which combines both electrical and thermal stability performances is proposed. Moreover, the impact of intermediate ITO (Indium Tin Oxide) ultra-thin film in enhancing the thermal stability of Au/Si Schottky Diode is presented. The proposed design thermal stability and electrical characteristics are investigated and compared with those of the conventional Schottky structures in order to reveal the device performance thermal stability. It is found that the amended Schottky diode design has a profound implication in improving the device reliability against thermal variations. Our experimental analysis is carried out incorporating the impact of the ITO thickness on the device performance, where an appropriate ITO thickness value can improve the electrical and thermal stability performances. This makes the Au/ITO/Si structure a potential alternative for high-performance and reliable power electronic and photovoltaic applications.

C.P.24
16:30
Authors : F. Alnjiman1, A. N. Fioretti3-4, S. Diliberto1, Y. Battie2, A., A. Zakutayev3, C. Tamboli3-4, JF. Pierson1, P. Miska1
Affiliations : 1- Institut Jean Lamour (UMR CNRS 7198), Université de Lorraine, CNRS, Nancy, France; 2- Laboratoire de Chimie et Physique – Approches Multi-échelles et Milieux Complexe, Université de Lorraine, Metz, France; 3 - National Renewable Energy Laboratory, Golden, Colorado 80401 USA; 4- Colorado School of Mines, Golden, Colorado 80401 USA;

Resume : Zinc tin nitride (ZnSnN2) is a new semiconductor material with earth abundant elements and a low-cost production. It has a tunable direct band gap (1.0–2.2 eV) that may be due to cation disorder [1]. It has recently attracted considerable interest for solar energy applications and high speed electronics to replace the III-V materials historically used in optoelectronics. This work presents the results of growth of ZnSnN2 thin films by reactive co-sputtering using zinc and tin metallic targets. The stoichiometry of the films was controlled by optimizing operating parameters such as the target voltage, the nitrogen partial pressure or the total pressure. By changing the total pressure, the morphology and the texture of the films can be tuned. We grew ZnSnN2 thin films with different pressure from 0.5-3.0 Pascal. The structure of the films was studied by X-ray diffraction and the morphology by scanning electron microscopy. More detailed information about the chemical environment of tin atoms has been obtained using 119Sn conversion electron Mössbauer spectroscopy. The optical band gap has been deduced from UV-Visible spectroscopy and ellipsometry measurements. The electrical resistivity, free electron concentration and Raman data are in agreement with literature. References [1] A. N. Fioretti, et al. in 2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC), 2015, p. 1‑5.

C.P.25
16:30
Authors : Robert Makin, Krystal York, Steven M. Durbin, Nancy Senabulya, James Mathis, Roy Clarke, Nathaniel Feldberg, Patrice Miska ,Christina Jones, Logan Williams, Emmanouil Kioupakis, Roger Reeves
Affiliations : Department of Electrical and Computer Engineering, Western Michigan University, 1903 W. Michigan Ave, Kalamazoo, MI 49008;Department of Electrical and Computer Engineering, Western Michigan University, 1903 W. Michigan Ave, Kalamazoo, MI 49008;Department of Electrical and Computer Engineering, Western Michigan University, 1903 W. Michigan Ave, Kalamazoo, MI 49008;Department of Applied Physics, University of Michigan, 500 South State Street, Ann Arbor, MI 48109;Department of Applied Physics, University of Michigan, 500 South State Street, Ann Arbor, MI 48109;Department of Applied Physics, University of Michigan, 500 South State Street, Ann Arbor, MI 48109;Université de Lorraine, Institut Jean Lamour, Vandoeuvre les Nancy;Université de Lorraine, Institut Jean Lamour, Vandoeuvre les Nancy;Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan;Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan;Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan; School of Physical and Chemical Sciences, University of Canterbury, New Zealand

Resume : Chalcopyrite semiconductors can undergo a transition between their equilibrium chalcopyrite structure and a reduced volume, higher symmetry unit cell through the introduction of disorder to cation sublattice. A completely random distribution of cations on the cation sublattice results in a reduction of the band gap relative to that of the chalcopyrite lattice. ZnSnN2 represents an interesting member of β-NaFeO2 compounds, a closely related system to the chalcopyrite family, due to its earth-abundant constituent elements and a band gap close to the range needed for terrestrial solar cells. Density functional theory calculations predict the ordered phase to have an orthorhombic lattice and a direct band gap of 2.0 eV. In contrast, the band gap of the completely disordered cation sublattice phase is predicted to be approximately 1.0 eV. A series of ZnSnN2 films with varying degrees of cation ordering have been obtained via plasma-assisted molecular beam epitaxy (PAMBE). The measured optical band gap of these samples matches the predicted dependence as a function of the sample’s order parameter as measured by Raman scattering and both x-ray and electron diffraction, and hence allows for the possibility of tuning the band gap of ZnSnN2 without having to alloy with other material systems. Additionally, we report growth of single crystal films of MgSnN2, a related β-NaFeO2 compound with a band gap predicted to be similar to that of GaN, also using PAMBE.

C.P.26
16:30
Authors : E. H. Sánchez(1), P. S. Normile(1), M. Andersson(2), S. S. Lee(3), M. Vasilakaki (4), M. Murgia(1), R. Mathieu(2), K. N. Trohidou (4), J. Nogués(5), J. A. De Toro(1)
Affiliations : (1) Instituto Regional de Investigación Científica Aplicada (IRICA) and Departamento de Física Aplicada, Universidad de Castilla-La Mancha, E-13071 Ciudad Real, Spain; (2) Department of Engineering Sciences, Uppsala University, Box 534, SE-751 21 Uppsala, Sweden; (3) Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669, Singapore; (4) Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, 153 10 Agia Paraskevi, Attiki, Greece; (5) Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC, Campus UAB, Bellaterra, 08193 Barcelona, Spain

Resume : The preparation of binary random compacts (BRCs) with different proportions of low- and high-anisotropy bare (no surfactant) oxide nanoparticles (NPs), each with a narrow size distribution, is shown to be an efficient method to tune the magnetic properties of such dense NP assemblies. Two series of such BRCs have been studied: one (MIX1) comprises nanoparticles with a moderate difference in effective magnetic anisotropy (maghemite NPs with volumes V and 2V, diameters 9.0 and 11.5 nm), whereas the particles mixed in series MIX2 (pure maghemite and Co-doped maghemite, both 6.8 nm in diameter) possess significantly different effective anisotropy. In both series the dipolar interactions are strong enough to fully couple the two types of NPs at low fields (e.g., yielding a single collective freezing). However the hysteresis loops of the MIX2 series are very similar to the weighted superposition of those measured in the pure systems (end members of the series), indicating that single particle anisotropy dominate in the magnetization reversal process. The effect of the varying dipolar interactions through the two series on the coercive and exchange bias fields is discussed and well-reproduced by Monte Carlo simulations. This effect should be taken into account, in addition to dominant exchange effects, in exchange-coupled (often rare-earth free) permanent magnets.

C.P.27
16:30
Authors : Muhammad Ibrahim Iqbal, Kwang-Deog Jung
Affiliations : Clean Energy Research Center, Korea Institute of Science and Technology, Cheongryang, Seoul 136-791, Republic of Korea; Department of Clean Energy and Chemical Engineering, University of Science and Technology, 217 Gajeong-ro Yuseong-gu, Daejeon 305-333, Republic of Korea

Resume : Carbon dioxide (CO2) emissions into the atmosphere and the oceans become a growing concern from the last few decades because of its effects on the rise of global temperature. It is a prediction of IPCC (intergovernmental Panel on Climate Change) that if CO2 emission continues to grow unhalted then by 2100 the mean surface temperature will rise upto 4oC. The IPCC and other reports suggest that CCS (Carbon Capture and Sequestration) is the most economically feasible way to mitigate CO2 emissions. CCS refers to several emerging technologies related to capturing and storage of CO2 into different geological sites. Mineralization, i.e., converting CO2 into carbonates and bicarbonates, is also a potential technique to alleviate issues related to emission of CO2. However, mineralization is not economically feasible for storing CO2, as expensive chemicals are required for extraction and carbonation of Ca ions. Recently, a method for production of high purity nano calcium carbonate (nCaCO3) starting from waste inorganics (Concrete, Steel slag) using both HCl and NaOH for sequestration of CO2 has been suggested. In order to make the process economically feasible, an energy efficient method for production of HCl and NaOH is required. If an electrolysis system can produce both HCl for Ca extraction and NaOH for carbonation with low energy consumption, mineralization of waste inorganics becomes an economically feasible approach to mitigate environmental CO2 emissions. For this purpose, NaCl electrolysis system with three compartments was fabricated; 1) an anode compartment for hydrogen oxidation, 2) a cathode compartment for hydrogen evolution, and (3) a central compartment between the anionic and cationic exchange membrane where the NaCl solution is introduced. Both 1 M NaOH and HCl were successfully co-produced with a caustic efficiency of 83.6% in the three-compartment cell from a 25 wt% NaCl solution at 1.5 V. Under those conditions, the equilibrium cell potential was 0.83 V. The current density under the optimized operating conditions was 40 mA cm geo−2, and the overpotentials of the cathode (1.0 mg Pt cm−2) and anode (0.2 mg Pt cm−2) were 0.09 V and 0.05 V, respectively. Further detail about cell design and process performance will be elaborated at conference.

C.P.28
16:30
Authors : Thi Hoa Vu, Anh Tuan Pham, Sunglae Cho
Affiliations : Department of Physics, University of Ulsan, 93 Daehak-ro, Nam-gu, Ulsan, 44610, Korea

Resume : Bismuth (Bi) and antimony (Sb), belonging to the rhombohedral structure, are semimetals, which have a small energy overlap between the conduction and valence bands, high carrier mobilities and small effective masses. Bi1-xSbx can be either a semiconductor or semimetal depending on the Sb concentration. Bi1-xSbx is semiconducting for 0.07 ≤ x ≤ 0.22, but otherwise semi-metallic. Because of its a small band gap, extremely high electron mobility and a small lattice thermal conductivity, Bi1-xSbx has been considered as a promising thermoelectric material operating around 80-200 K long time ago. According to the work of W.M. Yim and A. Amith, the application of magnetic field perpendicular to the thermal gradient and current direction can increase Seebeck coefficient while decreasing electrical and thermal conductivity. However, D. Shin’s report showed an opposite trend of electric conductivity as applying the longitudinal magnetic field in Bi0.96Sb0.04 single crystal. Here, we investigate the influence of anisotropy, temperature, transverse and longitudinal magnetic field on Seebeck coefficient, electrical and thermal conductivity of Bi1-xSbx (x = 0 – 0.24) single crystals in the wide temperature range 20 – 500 K. Detail will be discussed later.

C.P.29
16:30
Authors : Thi Toan Tran, Van Quang Nguyen, Thi Minh Hai Nguyen, Thi Hoa Vu, Sunglae Cho
Affiliations : Department of Physics, University of Ulsan, Ulsan, 44610, South Korea

Resume : The orthorhombic IV-VI monochalcogenides (SnSe, SnS, GeSe, GeS) have attracted considerable interest for the discovery of excellent thermoelectric performance. Some calculated publications also refer that Germanium sulfide (GeS) is very promising for thermoelectric applications as well as its excellent optical, photoelectrical and electric properties in two dimensional (2D-type). In this work, single crystal GeS was synthesized by gradient temperature method with the changing of concentration of precursor. Furthermore, GeS has been doped with some elements such as Ag, Sn, Se, Te and Bi. The structure and vibration properties of as-grown material were investigated by Raman spectra and X-ray diffraction (XRD). The surface morphology of GeS was also characterized using scan electron microscopy (SEM). We will discuss on the potential of these materials in electronic and optoelectronic devices.

C.P.30
16:30
Authors : M.L. Grilli1*, F. Menchini1, M. Yilmaz2, L. Serenelli1,3, R. Chierchia1, A. Mittiga1, A. Piegari1, M. Tucci1
Affiliations : 1ENEA - Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Casaccia Research Centre, Via Anguillarese 301, 00123 Roma, Italy 2Advanced Materials Research Laboratory, Department of Nanoscience and Nanoengineering, Graduate School of Natural and Applied Sciences, Ataturk University, 25240 Erzurum,Turkey 3Department of Information Engineering, Electronics and Telecommunications (DIET), University of Rome “Sapienza”, Via Eudossiana 18, 00184 Rome (Italy)

Resume : One of the applications of p-type transparent conductive oxides (TCOs) is as hole transport or electron-blocking layer in thin film solar cells or organic light emitting diodes (OLEDs). Many p-type TCOs use critical raw materials as constituents and, in addition, up to now none of the proposed materials shows performances comparable to n-type TCOs, which are suitable for application in the so-called invisible electronics. We have recently investigated the characteristics of RF sputtered NiO films as a function of some growth parameters (RF power, oxygen pressure, sputtering pressure), and we have obtained highly conductive thin films. In this work we present results of preliminary studies on the effect of substrate bias on the electrical and optical properties of NiO films, that were carried out with the aim to further increase films’ performances.

C.P.31
16:30
Authors : M.R. Mancini1*, M. L. Grilli1*, L. Pilloni1, A. Mancini2,
Affiliations : 1ENEA - Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Casaccia Research Centre, Via Anguillarese 301, 00123 Roma, Italy 2ENEA - Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Frascati Research Centre, Via Enrico Fermi 45, 00044 Frascati (Rome), Italy

Resume : The disposal of end-of-life Li-ion batteries must compliance to safe regulations because spent batteries are classified as hazardous wastes, therefore increasing transportation and treatment costs. Recycling technologies with lower environmental impact and lower costs as alternative to classical hydrometallurgical and pyrometallurgical processes are needed. In addition, recycling of primary raw materials becomes a need if the materials has got a high supply risk. In Li-ion batteries both Co and graphite are listed among critical raw materials for EU. Natural graphite powders are mainly produced in China, which holds a 70% share of total world production, followed by Latin America with 20%. Europe production of natural graphite powders is less than 1%. In this work, we describe an eco-friendly method for recovering graphite powders from anodes of end of life Li-ion batteries. Recovered graphite powders were used as starting material for the synthesis of graphene oxide by modified Hummers’ method. Graphene oxide films were deposited on fused silica and silicon substrates by spin coating and drop casting techniques starting from graphene oxide water solution. Thermogravimetical analysis (TGA/DTA), UV-Vis-NIR and FTIR spectrophotometry, XRD, and electron microscope (FE-SEM) measurements were used to investigate GO solutions, powders and films characteristics.

C.P.32
16:30
Authors : N. Laidani (1), K. M. Safeen (1,2), R. Bartali(1), G. Gottardi(1), V. Micheli (1)
Affiliations : (1) Bruno Kessler Foundation, Centre for Materials and Microsystems, Via Sommarive 18, 38123 Trento, Italy (2) Abdul Wali Khan University, Department of Physics, 23200 Mardan, Pakistan

Resume : Doped environmental friendly oxide-based films have emerged as important and promising materials for a wide range of applications such as photovoltaics, photocatalysis, optoelectronics and electronics. In particular, for transparent electrodes fabrication, there is a huge interest to develop transparent and conductive materials which use less scarce elements than indium as an alternative to indium-tin-oxide. The present work deals with oxide films synthesis processes using radio-frequency sputtering technique in Ar and Ar-O2 discharges, the film stoichiometry control and structural defect identifying, to produce transparent and conductive films. Nb-doped titanium dioxide (TiO2:Nb) thin films were considered. Two types of niobium-containing sputtering targets, Nb metal and Nb2O5 , were employed simultaneously with a ceramic TiO2 target. The film growth-properties relationship was studied to understand the factors influencing the doping process at temperatures ≤350 °C. The lowest resistivity obtained was for the intrinsically - extrinsically co-doped (by oxygen vacancies and Nb respectively) TiO2 and in the range (1×10-3 - 7.4×10-4 ) Ω.cm with an optical transparency of 65-90% in the wavelength range 400-750 nm.

C.P.33
16:30
Authors : Alberto López-Ortega1, Sreekanth Perumbilavil2, Gaurav Kumar Tiwari3, Tamio Endo4,5, Josep Nogués6,7, Reji Philip3
Affiliations : 1CIC nanoGUNE, Tolosa Hiribidea, 76 E-20018 Donostia-San Sebastian, Spain. 2Photonics Laboratory, Tampere University of Technology, P.O.Box 692, FI-33101, Tampere, Finland. 3Ultrafast and Nonlinear Optics Lab, Light and Matter Physics Group, Raman Research Institute, Bangalore 560080, India. 4Emeritus Professor, Mie University, 514-8507, Mie, Japan 5Faculty of Engineering, Gifu University, 501-1193 Gifu, Japan. 6Catalan Institute of Nanoscience and Nanotechnology (ICN2), Campus UAB, Bellaterra, 08193 Barcelona, Spain. 7Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.

Resume : Nonlinear optical nanostructured materials are gaining increased interest as optical limiters for various applications, although many of them suffer from reduced efficiencies at high-light fluences due to photo-induced deterioration. We report the nonlinear optical properties of ferrite core/shell nanoparticles showing their robustness for ultrafast optical limiting applications. At 100 fs ultrashort laser pulses, the effective two-photon absorption (2PA) coefficient shows a non-monotonic dependence on the shell thickness, with a maximum value obtained for thin shells, indicating that core/shell is an advantageous morphology to improve the nonlinear optical parameters with excellent optical limiting performance and optical limiting threshold fluences. These values are comparable to or better than most of the recently reported optical limiting materials. The quality of the open aperture Z-scan data recorded from repeat measurements at intensities as high as 35 TW/cm2, indicate their considerably high optical damage thresholds in a toluene dispersion, ensuring their robustness in practical applications. Thus, the high photostability combined with the remarkable nonlinear optical properties make these nanoparticles excellent candidates for ultrafast optical limiting applications.

C.P.34
16:30
Authors : Alberto López-Ortega1, Mari Takahashi2, Shinya Maenosono2 and Paolo Vavassori1,3
Affiliations : 1CIC nanoGUNE, E-20018 Donostia - San Sebastian, Spain 2School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan 3IKERBASQUE, The Basque Foundation for Science, E-48013 Bilbao, Spain

Resume : The combination of magnetic and plasmonic materials and their nanostructurization have been revealed a prominent pathway to develop novel photonic nanostructures, called magneto-plasmonic nanostructures, for the active control of the light polarization at the nanoscale using a magnetic field. Up to now, the physical growth methods have shown the only robust and reproducible, and therefore exploitable, approach to prepare these types of nanostructures. Here, we demonstrate the chemical synthesis of magneto-plasmonic core/shell nanocrystals of high quality and with enhanced magnetic control of optical properties comparable to the best results reported for nanostructures growth by physical method. Hybrid Ag/FeCo core/shell nanocrystals have been synthesized in a combination of hot injection and polyol approaches in high boiling point solvents, demonstrating that the well-defined structures of both components, their interface, and the optimized morphology, where the plasmonic and magnetic components are placed in the core and the shell regions, are the responsible of the observed large enhancement of magnetic control of light polarization. Therefore, it has been confirmed the possibility to develop tunable magneto-optical materials by hybrid magneto-plasmonic structures synthesized by chemical methods.

C.P.35
16:30
Authors : Javier Rial, Melek Villanueva, Ester M. Palmero, Julio Camarero, Noelia López, Alberto Bollero
Affiliations : Division of Permanent Magnets and Applications, IMDEA Nanoscience, 28049 Madrid, Spain

Resume : Demand of permanent magnets (PMs) is increasing yearly, due to the development of new technological applications. The critical situation of some raw materials (heavy rare-earths (RE), in particular) contained in many technological PMs makes necessary to find alternatives in as many applications as possible. One of the best candidates to substitute RE-PMs in the gap of 5-12 MGOe is MnAl. A theoretical (BH)max=12MGOe and a low density of 5200 kg/m3 make MnAl a potential light-weight PM. The ferromagnetic τ-phase (L-10 structure), the only ferromagnetic phase in the MnAl alloy, can be obtained from the metastable ɛ-phase; but the ɛ-phase can decompose into the non-magnetic γ2 and β-Mn phases during processing. The present study shows the development of high coercive MnAl powders by milling gas-atomized Mn54Al46 particles for an unprecedented short duration of 30-270 seconds followed by annealing [1]. This ultrafast-milling technique [2,3] allows the development of coercive fields above 4 kOe (5 kOe) after 30 s (270 s) of milling. This means a dramatic improvement by comparison with several to tens of hours reported in the literature to produce isotropic MnAl powders with comparable coercivity. References [1] J. Rial et al., J. Phys. D: Appl. Phys. 50, 105004 (2017). [2] F.J. Pedrosa et al., Appl. Phys. Lett. 109, 223105 (2016). [3] F.J. Pedrosa et al., RSC Adv. 6, 87282 (2016).

C.P.36
16:30
Authors : Min Seob Kim1, Young Hun Lee1, Dongin Jeong1, Hyung Wook Choi2, Sintayehu Nibret Tiruneh1, Mohit Kumar1, Bong Kyun Kang3, Dae Ho Yoon1,2
Affiliations : 1. School of Advanced materials Science & Engineering, Sungkyunkwan University(SKKU), Suwon, 440-746, Republic of Korea; 2. SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University(SKKU), Suwon, 440-746, Republic of Korea; 3. Electronic Materials and Device Research Center, Korea Electronics Technology Institute (KETI), 25 Saenari-ro, Bundang-gu, Seongnam-si, Gyeonggi-do, 13509, Republic of Korea

Resume : Supercapacitor is one the most promising electrical energy storage for applying scientific fields such as hybrid vehicle and portable electric device. Hollow structures with nanosheets and binary transition metal sulfides (BTMSs) are two important key factors to enhance the electrochemical performance of electrode materials for supercapacitor. Hollow structures with nanosheets can maximize specific surface area of the electrode material for improved capacitance. The BTMSs, such as manganese-cobalt sulfides have several outstanding advantages; rich redox reactions, the synergistic effects by interaction between metal compounds, and better electrical conductivity than transition metal oxides. Herein, we successfully synthesized the hollow structured manganese cobalt sulfide nanocubes by 3-step process. The morphology, crystallinity and chemical composition of MnxCo3-x[Co(CN)6]2 nanocubes, manganese-cobalt hydroxides, and manganese- cobalt sulfides were confirmed by SEM, TEM, XRD, and FT-IR.

C.p.37
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Photovoltaics : Phillippe Smet
08:45
Authors : Manuel Salado, Samrana Kazim and Shahzada Ahmad
Affiliations : Basque Center for Materials, Applications and Nanostructures (BCMaterials), Martina Casiano, UPV/EHU Science Park, Barrio Sarriena s/n, Leioa 48940, Spain

Resume : Perovskites solar cells have emerged as a beacon in thin film photovoltaic technology. The power conversion efficiencies (PCE) has reached to a level of mature thin film technology, which took decades to reach the similar performance of 22.7 %. To improve the inherent challenges, compositional engineering of perovskites as well as molecular engineering of hole transport materials (HTMs) were adopted, without the use of any critical raw materials. Device performance and stability was subsequently enhanced to an extent. However, the intrinsic as well as extrinsic stability of perovskites remains problematic for its real potential applications. Here, the use of an optimized passivation layer is seen as an ideal approach to protect the surface from extrinsic attack, without altering the electro-optical properties. We will describe our findings on the role of passivation layer and compositional engineering approach to protect the perovskite layer from atmospheric attack. An improved PCE was also obtained compare to reference devices, as the passivation layer will restricts the flow of electron towards the HTM layers and lower recombination was obtained. A batch-to-batch reproducibility with ±0.5% PCE was achieved along with very competitive efficiencies of 20%.

C.4.1
09:15
Authors : Sergio Castro-Hermosa, Janardan Dagar, Andrea Marsella, Giulia Lucarelli, Thomas M. Brown
Affiliations : CHOSE (Centre for Hybrid and Organic Solar Energy), Department of Electronic Engineering, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy.

Resume : The first perovskite solar cells (PSC) fabricated directly on a paper substrate are here reported. The paper PSCs were developed with a low-temperature Paper/Au/SnO2/meso-TiO2/CH3NH3PbI3/Spiro-OMeTAD/MoOx/Au/MoOx architecture utilizing a Au/SnO2 and MoOx/Au/MoOx stack as electron- and hole- extracting electrodes respectively, delivering state of the art power conversion efficiency of 2.7% for solar cells prepared directly on the opaque paper substrate. The transparent top MoOx/Au/MoOx electrode had a favourable combination of transmittance (62.5%) and sheet resistance (9 Ω/□). Opaque and transparent bottom electrodes were also designed. By comparing performance of cells on paper with those fabricated on glass and plastic films with different electrodes, we identify avenues that can help guide future research for improved performance. All the deposition processes used are scalable and compatible with large area printing or evaporation technologies. Paper represents a lightweight, flexible, inexpensive, ubiquitous, and environmentally friendly material, paving the way for integrating perovskite semiconductor technology with other electronic components as well as for the development of stand-alone PV devices on low-cost and recyclable cellulose paper substrates.

C.4.2
09:30
Authors : Zhuoyin Peng, Zhou Liu, Jianlin Chen, Jian Chen
Affiliations : Key Laboratory of Efficient & Clean Energy Utilization, The Education Department of Hunan Province, Hunan Province 2011 Collaborative Innovation Center of Clean Energy and Smart Grid, School of Energy and Power Engineering, Changsha University of Science and Technology, Changsha 410111, P. R. China

Resume : With the advantages of simple preparation process and high efficiency, perovskite solar cells have become most industrial potentiality in new-type solar cells. However, with the disadvantages of high-cost and low hole mobility on spiro-OMeTAD hole transport materials, inorganic hole transport layer have become significant investigation area of perovskite solar cells. Due to the advantages of high stability, simple preparation process, high hole mobility and size-effect, CuSbS2 quantum dot have been considered as a excellent hole transport materials for perovskite solar cells. In the present work, CuSbS2 quantum dot are prepared with different size and surface passivation process for hole transport layer of perovskite solar cells by spin-coating process. With the size decreasing of quantum dots, the distinction of band energy between hole transport layer and optical absoprtion layer will be increased, which can improve the open-circuit voltage of the solar cells. And CH3CH2I and ZnSe have been introduced for the passivation layer of CuSbS2 quantum dots. It can effectively enhance the photovoltaic conversion efficiency of perovskite solar cells, which have higher short-circuit current density than that of spiro-OMeTAD hole transport materials. These investigations of size and surface passivation process on CuSbS2 quantum dot hole transport materials can provide a perspective area on development of quantum dot hole transport materials.

C.4.3
09:45
Authors : Mriganka Singh, Chien-Hung Chiang, Gang Li, Chun-Guey Wu, Hong-Cheu Lin, and Chih-Wei Chu
Affiliations : Mriganka Singh and Hong-Cheu Lin: Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan, Republic of China; Chien-Hung Chiang and Chun-Guey Wu: Research Center for New Generation Photovoltaics, National Central University; Gang Li: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China; Chih-Wei Chu: Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan

Resume : An environmental friendly method adopts for the fabrication of anatase titanium dioxide (an-TiO2) as electron transporting layer (ETL) at room temperature was developed for efficient perovskite solar cells (PSCs). Both small and large area device demonstrate the favorable efficiency for PSCs. Grinding TiO2 is a new class of promising material which is suitable for both plastic as well as other flexible substrates manufacturing because of his room-temperature annealing process. The frequently used ETL is an-TiO2 material because of its superior semiconductor characteristics, outstanding optical transmittance and suitable band alignment. Herein, we report for the first time a room-temperature (< 30 ℃), low cost massive production of ETL is developed by grinding of large clumps of an-TiO2 material to achieve suspension of a nanoparticles (NPs) of TiO2 for meso-superstructured PSCs. This process does not required any chemical synthesis, it is purely physical process. Therefore, the weighty nature of oxygen and water protection on an-TiO2 NPs provides a uniform and smooth surface. The lowest unoccupied molecular orbital (LUMO) of the ground an-TiO2 NPs, estimated by ultraviolet photoelectron spectroscopy (UPS), was 4.06 eV, which is salient feature for active layer. When using the solution-processed ground an-TiO2 NPs as the ETL imitative from a 1.5wt % concentration, the resulting CH3NH3PbI3-based PSCs exhibit a champion power conversion efficiency (PCE) at room-temperature (< 30 ℃) of 17.43% with an active area of 0.1cm2. We used same strategy to fabricate a large-area CH3NH3PbI3 film (mask area 25.2 cm2), and achieved a PCE of 14.19%. PSC devices incorporating the ground an-TiO2 NPs as ETLs exhibited attractive long-term device stabilities, with PCEs retaining approximately 85% of their initial values after 80 days, which will open a new paradigm for commercialization for PSCs.

C.4.4
10:00
Authors : Vanira Trifiletti, Silvia Mostoni, Roberto Scotti, Simona Binetti
Affiliations : University of Milano-Bicocca, Department of Materials Science and Solar Energy Research Center (MIB-SOLAR), Via Cozzi 55, Milan (Italy)

Resume : Thin photovoltaics based on chalcopyrite film, Cu(In,Ga)Se2 (CIGS) and related alloys, have exhibited so far efficiency over 22,3% on the laboratory scale. However, the CIGS solar cells scale-up is expected to be hampered because of the low availability of In and Ga in the Earth crust. The most promising next leader in the chalcogenide thin film technology seems to be the kesterite compound Cu2ZnSnS4 (CZTS), as it is based on earth-abundant elements and it shows the better results when low-cost solution processable techniques are employed in the fabrication. Solution-processed inorganic semiconductors, in fact, offer a rising route for the low-cost mass production of solar cells In this context, we present a new chemical procedure to obtain a superior quality Cu2ZnSnS4 and Cu2FeSnS4 thin films composed of highly soluble and inexpensive precursors in a non-toxic and environmentally friendly solvent. The films were prepared by a Sol-Gel method and the deposition was carried out by in situ gel formation on fluorine doped tin oxide coated glass. The films obtained were characterized by Raman spectroscopy, X-ray diffraction, energy dispersive X-ray analysis, photoluminescence spectroscopy and by electronic scanning microscopy. The developed methodology has successfully identified an innovative way to achieve high-quality kesterite thin films for photovoltaic applications; relate devices optimization is currently underway.

C.4.5
10:15
Authors : E. Pinna (1,2), C. Melis (1,2), A. Antidormi (1,2), R. Cardia (1), E. Sechi (1), G. Cappellini (1), M. D’Ischia (3), A. Vacca (4), M. Mascia (4), L. Colombo(1,2), G. Mula (1,2)
Affiliations : 1Dipartimento di Fisica, Università degli Studi di Cagliari, S.P. 8 km 0.700, 09042 Monserrato, Italy; 2 CNR-IOM, Unità di Cagliari SLACS, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Monserrato, Italy; 3 Department of Organic Chemistry and Biochemistry, University of Naples “Federico II”, via Cintia 4, 80126 Naples, Italy; 4 Dipartimento di Ingegneria Meccanica Chimica e dei Materiali, Università degli Studi di Cagliari, Piazza d’Armi, 09126 Cagliari, Italy

Resume : In the field of renewable energy production, porous Si/eumelanin hybrids are a novel interesting class of organic–inorganic materials for photovoltaic applications. One of the main issues of this junction that prevented the construction of a marketable devices is, however, the photocurrent temporal stability. In the perspective of solving this problem, the understanding of the polymerization mechanisms and of the eumelanin–Si interface formation is needed. We report herein an integrated experimental and computational study to investigate the samples stability. Different experimental strategies have been proposed, both related to the interface modification and to the methods that can be used to impregnate the inorganic porous matrix. Moreover, from the computational point of view, the organic-inorganic interface formation has been simulated, studying the 5,6-dihydroxyindole (DHI) monomer evolution and its adhesion to silicon. A first improvement in the junction stability can be obtained with a mild oxidation of the porous silicon surface because of the enhancement of the DHI–surface interaction, and calculations have shown that the higher oxidation states in DHI oligomers create more favorable conditions for the efficient adhesion of eumelanin on silicon surface. REFERENCES: [1] G. Mula et al., Nanoscale Res Lett 2012, 7, 377; [2] Pinna et al., RSC Advances, 2015, 5, 56704; [3] E. Pinna et al., Int J Mol Sci 2017, 18, 1567; [4] L. Panzella et al. Angew Chem Int Edit 2013, 52.

C.4.6
10:30 Coffee Break    
 
TCO & optolectronics 2 : Patrice Miska & Carlo Ricci
11:00
Authors : M. L. Grilli a, R. Vernhes b, I. Di Sarcina a, T. Dikonimos a, L. Martinu b, A. Piegari a
Affiliations : a ENEA, Casaccia Research Centre, Via Anguillarese 301, 00123 Rome, Italy b Polytechnique Montreal, 2500 chemin de Polytechnique, H3T1J4 Montreal, QC, Canada

Resume : ITO is a unique material with optical and electrical characteristics that at present make it the material of choice in displays, touch screens, solar cells and optoelectronic devices. However, ITO is not suitable for UV and NIR applications and, in addition, is listed among the critical raw materials (CRMs) for EU due to its high supply risk. Therefore alternative materials with similar properties should be identified. In this work we fabricated atomically smooth ultrathin and electrical stable nickel films, by using radio frequency sputtering at room temperature. Continuous films with low resistivity down to 5.6x10-5 Ω·cm and wide spectral range transparency were achieved for thicknesses of a few nanometers without using any seed layer. A novel method based on angle resolved transmittance and reflectance measurements allowed the calculation of the refractive index and extinction coefficient of a Ni films with thickness of about 5 nm.

C.5.1
11:30
Authors : Krishna Manwani, Emila Panda
Affiliations : Department of Materials Science and Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar 382355, Gujarat, India

Resume : Finding an alternative to expensive tin doped Indium oxide as a TCO layer has been a challenge for thin film solar industry. In this regard, doped-TiO2 is a promising alternative to the conventional TCOs, because it is an inexpensive, non-toxic, chemically and electrically stable transparent material with wide optical band gap (Eg; 3.2 eV for anatase). In this study, Ta-doped TiO2 films are successfully fabricated by RF magnetron sputtering by varying a wide range of experimental parameters, such as, dopant concentration, substrate temperature, substrate type, film thickness, post-deposition annealing and microstructure of the seed layer. A detailed microstructural and optoelectronic characterization of all these films are then carried out by using a combination of experimental techniques, like, GI-XRD, AFM, FESEM, XPS, UV-Vis-NIR, PL spectroscopy and Hall effect measurement system. Growth of high quality anatase TiO2 with strong (101) peak and with no presence of rutile, Ta, and/or Ta2O5 is observed. Whereas electrical properties of these films are found to be strongly dependent on the microstructure, all these films are found to be highly transparent with an average transmittance of 80% in the visible range. Blue shift is observed in these films with average Eg being 3.6 eV, which is larger as compared to the bulk Eg of anatase TiO2. Understanding developed in this study might help in tuning the process parameters to design the Ta-doped TiO2 films for the desired application.

C.5.2
11:45
Authors : Matthew Zervos (1), Andreas Othonos (1), Eugenia Tanasu (2) and Eugeniu Vasille (2)
Affiliations : (1) Nanostructured Materials and Devices Laboratory, School of Engineering, University of Cyprus, 75 Kallipoleos, PO Box 20537, Nicosia, 1678, Cyprus. (2) Department of Science and Engineering of Oxides Materials and Nanomaterials, Politehnica University of Bucharest, 313 Splaiul Independentei, Bucharest, 060042, Romania

Resume : Transparent conducting oxides such as Sn doped In2O3 nanowires (NWs) have been investigated in the past since they are important building blocks for the realization of novel electronic and optoelectronic devices like solar cells, but In is rare and expensive [1]. Similarly Sb doped SnO2 NWs are also transparent and exhibit metallic like conductivities but they are more attractive since Sn is abundant and not expensive. In the past free standing, SnO2 NWs have been grown on c-axis oriented sapphire with a certain degree of alignment while planar and aligned SnO2 NWs have also been obtained sapphire [2] . Here we will describe the growth of highly aligned, free standing and straight Sb doped SnO2 NWs with diameters of a few tens of nm's and lengths reaching up to several tens of um that were obtained by the vapor liquid solid mechanism on r- oriented sapphire using Au as a catalyst. We show that orthogonally oriented Sb doped SnO2 NWs with a highly regular and uniform mesh structure may be obtained on m-oriented sapphire. The electrical and optical properties of the Sb doped SnO2 NWs have been measured by (a) THz conductivity and (b) ultrafast pump probe spectroscopies. More importantly we show that the Sb doped SnO2 NWs can be grown at selective locations thereby forming ordered arrays with definite spacing's. This enables one to tailor the absorption and transmission spectra while maintaining a high conductivity which is important for the development of novel optoelectronic devices in conjunction with other organic or inorganic materials. [1] M.Zervos et al., Broad compositional tunability of indium tin oxide nanowires grown by the vapor liquid solid mechanism', Applied Physics Letters Materials, 2, p.056104 (2014). [2] X.Wang et al., Aligned Epitaxial SnO2 Nanowires On Sapphire : Growth and Device Applications, Nano Letters., 2014, 14 (6), pp 3014–3022

C.5.3
12:00
Authors : J. López-Vidrier,1 S. Gutsch,1 O. Blázquez,2 J. L. Frieiro,2 D. Hiller,1 S. Hernández,2 B. Garrido,2 M. Zacharias1
Affiliations : 1Laboratory for Nanotechnology, IMTEK, Faculty of Engineering, University of Freiburg, Georges Köhler Allee 103, 79110, Freiburg, Germany; 2MIND-IN2UB, Departament d’Electrònica, Universitat de Barcelona, Martí i Franquès 1, E-08028, Barcelona, Spain

Resume : Bandgap-tunable silicon nanocrystals (Si NCs) have been widely studied towards their application in light-emitting diodes (LEDs). For these devices, the selection of a proper material as top electrode has to meet specific criteria regarding conductivity and transparency. ZnO is currently being employed as transparent conductive oxide (TCO) in solar cell applications because it is a non-toxic and earth abundant material, but it could be also used as top electrode for LEDs. Moreover, because of its luminescence properties, ZnO could also become an interesting candidate as luminescent TCO contact; however, to date, this material has not been exhaustively explored. In this work, we analyse the electroluminescence (EL) properties of Si NC/SiO2 multilayers embedded in a metal-insulator-semiconductor device structure, with ZnO as top contact. DC EL emission is influenced by both the defect states within the ZnO electrode and the quantum-confined contribution from Si NCs. In addition, pulsed electrical excitation was found not only to enhance the total EL intensity by one order of magnitude, but also to modulate the ratio between the ZnO and Si NCs contributions to luminescence. This effect was investigated via recombination dynamics, which allowed modelling the excitation mechanism in terms of sequential carrier injection. Overall, this work highlights the importance of employing luminescent ZnO TCO to expand the EL emission from Si NC-based LEDs towards the visible range.

C.5.4
12:15 Lunch break    
 
Magnetic Materials 1 : Ester Palmero, Jose A. De Toro
14:15
Authors : Alberto López-Ortega1, Cesar de Julián Fernández2, Claudio Sangregorio3
Affiliations : 1CIC nanoGUNE, E-20018 Donostia-San Sebastian, Spain. 2CNR-IMEM, Parma, Italy. 3INSTM and CNR-ICCOM, Sesto Fiorentino (Firenze), Italy.

Resume : Magnetic nanoparticles (NPs) have attracted a great interest in the last decades thanks to their novel fundamental properties emerging from their extremely reduced size. Special attention has been devoted to Co-ferrite (CoxFe3-xO4) NPs due to their cheap manufacturing and high magnetic anisotropy. In particular, the application of Co-ferrite in the realization of permanent magnet has attracted a renewed interest as an alternative to rare-earth base materials in low energy applications. Therefore, a deeper understanding of the structural, size-dependent and morphological effects on final magnetic properties appears necessary. Herein, we present the chemical synthesis of a series of Co-ferrite NPs with a broad range of particle sizes (from 4 to 60 nm). We evaluated the (BH)max product, the figure of merit of permanent magnets, obtaining the maximum values ever reported in the literature for Co-ferrite NPs (i.e., 2.1 MGOe). Moreover, In a second step, we have used these Co-ferrite NPs for building blocks of more complex heterostructures based on antiferromagnetic(AFM)|ferrimagnetic(FiM) core|shell (CS) particles. The CS structure has been generated by topotaxial oxidation of the core region. The sharp interface, the high structural matching between both phases and the good crystallinity of the AFM material have been structurally demonstrated and are corroborated by the robust exchange-coupling between AFM and FiM phases. These properties induce a huge improvement of the capability of storing the energy of the material, a result which suggests that the combination of highly anisotropic AFM|FiM materials can be an effective strategy towards the realization of novel Rare Earth-free permanent magnets.

C.6.1
14:45
Authors : Kevin Sartori,1 Mathias Dolci,1 Yu Liu,1 Xiaojie Liu,1 Walid Baaziz,1 Sylvie Bégin Colin,1 Benoit P. Pichon 1,2,*
Affiliations : 1 Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000 Strasbourg, France 2 Institut Universitaire de France

Resume : Nanoparticles featuring a high magnetic anisotropy are strongly desired for applications related to spintronics such as mass storage media or magneto resistive sensors. Nevertheless, highly anisotropic nanomagnets usually require critical raw materials (CRMs) such as rare earth or platinum group metals. In contrast, abundant materials such as iron oxide (Fe304) nanoparticles are very well-known thanks to their superparamagnetic properties. Therefore, the enhancement of the magnetic anisotropy of Fe3O4 nanoparticles in order to produce blocked magnetic single domain nanoparticles at room temperature is highly challenging. In this context, exchange-coupling in bimagnetic nanoparticles is a very attractive tool. Indeed, a magnetic shell with a high magnetic anisotropy grown onto a Fe3O4 nanoparticle is a very efficient way to enhance their effective magnetic anisotropy. We will report on the design of Fe3O4 nanoparticles which combine additional magnetic components in order to enhance their magnetic anisotropy through exchange coupling. Further, we will present some results on their collective magnetic properties as function of their spatial arrangement when assembled onto substrate.

C.6.2
15:00
Authors : S. Marenkin, A. Kochura, A. Ril, I. Fedorchenko O. Rabinovich, S. Legotin, S. Didenko
Affiliations : Russian Academy of Science. Institute of General and Inorganic Chemistry, Moscow, Russia National University of Science and Technology MISIS, Moscow, Russia

Resume : MnSb thin films are promising for semiconductor-ferromagnetic structures and spintronic devices. The synthesis was carried out under high vacuum conditions using antimony and manganese films obtained by separate sputtering. The evaporator temperatures were chosen based on the calculation of Mn and Sb vapor flux densities. The stoichiometric composition of MnSb was obtained when the metal condensation fluxes were equal. Sitall and Si wafers were used as the substrates. The speed, evaporation time and substrates temperature were experimentally determined so that the films thickness and the crystallites size composing the film did not exceed 200 and 600 nm, correspondently. Due to high chemical activity of the metal nanolayers, the manganese antimonide growth occurred at temperatures lower than the MnSb peritectic decomposition temperature. Best structures, both the single-crystal MnSb films and their interfaces were obtained on Ge/Si substrates by the MBE. Nanostructures based on MnSb with 1D, 2D, and 3D self-organization can be obtained by Mn and Sb simultaneous deposition in ultrahigh vacuum to highly oriented pyrolytic graphite. The synthesis process was studied by X-ray diffraction, optical and electron microscopy, AFM and MFM. The optimal annealing conditions were determined: 350-400 °C and 3-4 hours. According to the of MFM data, the grown films had ferromagnetic properties.

C.6.3
15:15
Authors : Daniel Salazar, Andrés Martin-Cid, Ana Maria Schönhöbel, Rajasekhar Madugundo, Cristina Echevarria, Manuel Barandiaran, George Hadjipanayis
Affiliations : BCMaterials; University of the Basque Country; University of Delaware

Resume : Because of the criticality of rare earths (RE), the trend these days is to develop rare earth free/lean magnets as alternatives to Nd-Fe-B (2:14:1 phases) and Sm-Fe(Co) magnets. High performance permanent magnets must have high values of saturation magnetization MS, anisotropy field Ha, Curie temperature Tc (> 300º C) and the proper microstructure that leads to high coercivity. The 1:12 compounds RE-Fe12 with ThMn12 structure have excellent intrinsic properties (MS, Ha, Tc) but it is difficult to develop the proper microstructure that will prevent the nucleation of reversed domains and/or pin the domain walls. In this work, we will present the effects of the microstructure on the coercivity of RE-lean magnets. In samples with the 2:14:1 phase we have obtained large values of coercivity (Hc=2.5T), which is very high regarding its anisotropy field (37%-Ha), after infiltration of nanocrystalline melt-spun alloys. In alloys with 1:12-phases the coercivity is still low, reaching maximum values of Hc=0.5T in samples with Ha>10T. More detailed results of our research work during the past few years will be presented and discussed. This work is supported by the NOVAMAG Project (No. 686056) and DOE.

C.6.4
15:30
Authors : A. Bollero(1), J. Rial(1), M. Villanueva(1), A. Seoane(2), J. Almunia(2), R. Altimira(2)
Affiliations : (1) Division of Permanent Magnets and Applications, IMDEA Nanoscience, 28049 Madrid, Spain; (2) Ingeniería Magnética Aplicada IMA S.L., 08291 Ripollet, Barcelona, Spain

Resume : Ferrites enjoy a unique position in the group of permanent magnets due to their commercial importance. They are used in low field and low power applications, high-frequency systems... Based on their high demand, recycling of the residues generated in the manufacturing process is beneficial from an environmental point of view but also economically to reduce costs at the magnet company while additionally guarantying sustainability by closing the loop in production line. The Sr-ferrite (SrFe12O19) residue used in this study was collected in the permanent magnet factory in the shape of moisture comprising magnetic powder, water and coolant fluid. Application of a calcination process, under similar parameters to those used by the company in production, results in a recycled Sr-ferrite powder with a high coercivity value (3.3 kOe) above 3.5 times larger than that of the powder acquired by the company for magnets fabrication. The improvement in magnetic properties is the result of an efficient nanostructuration and homogenization of the powder [1]. This has been additionally proven by studying microstructural and magnetic modifications induced by application of a self-developed surfactant-assisted rapid-milling method [2,3] to the commercial Sr-ferrite powder. References [1] A. Bollero et al., ACS Sustainable Chem. Eng. 5, 3243 (2017). [2] J. Rial et al., J. Phys. D: Appl. Phys. 50, 105004 (2017). [3] F.J. Pedrosa et al., Appl. Phys. Lett. 109, 223105 (2016); RSC Adv. 6, 87282 (2016).

C.6.5
15:45 Coffee Break    
 
Recycling 1 : Alberto Bollero
16:15
Authors : Eva Brouwer(1), Mario Schönfeldt(1), Oliver Diehl(1), Andrea Gassmann(1), Karsten Rachut(1), Jürgen Gassmann(1), Rudolf Stauber(1), Oliver Gutfleisch (1,2)
Affiliations : (1) Fraunhofer ISC – Project Group Materials Recycling and Resource Strategies IWKS, 63457 Hanau, Germany; (2) Technische Universität Darmstadt, Functional Materials, 64287 Darmstadt, Germany

Resume : Whenever it comes to applications requiring magnets of highest energy densities, like in e-mobility, wind turbines, robotics etc. rare earth (RE) permanent magnets based on Nd-Fe-B are the material choice. With their outstanding performance they are key components in numerous applications and often not substitutable without performance losses. The transition in energy and transportation sectors as well as automatization will increase significantly the demand for efficient magnet material in the near future. The required RE elements are mainly mined in Asia, with China being by far the dominating player in the market – not only regarding the production of the RE elements and RE permanent magnets, but also as important manufacturer of devices. For Europe, being deprived in RE mineral resources and strategic metals in general but having an economy strongly depending on those materials, this situation should be regarded as highly critical. One way to lower the supply risk for Europe is to make use of the magnet material already circulating in the technosphere: either by reprocessing back to the individual RE elements or their oxides, or by employing functional recycling, i.e. refeeding the permanent magnet intermetallic compound back into the process chain to avoid the costly and energy-intensive separation steps. In this presentation, we highlight current RE criticality aspects and demonstrate how new fully dense sintered, hot-deformed and anisotropic polymer bonded permanent magnets of good quality can be processed from recycled scrap magnet material – at lower economic and ecological costs than magnets made of primary materials.

C.7.1
16:45
Authors : Cristian Tunsu Martina Petranikova
Affiliations : Chalmers University of Technology Department of Chemistry and Chemical Engineering Nuclear Chemistry and Industrial Materials Recycling Kemivägen 4, 41296 Göteborg, Sweden

Resume : There are constant efforts being done to reduce greenhouse gas emissions. Rare earth elements (REEs) play a significant role in these, being essential for green energy production, and for the efficient use of energy. Rare earths are essential constituents of wind turbine generators, fluorescent lamps, LED lamps, electric vehicles, hybrid electric vehicles, and magnetocaloric materials for efficient refrigeration applications. Magnetocaloric refrigeration is expected to replace traditional gas refrigeration, which is responsible for a significant part of the energy consumption. As REEs are at the core of many future-sustainable technologies, they are in high demand, and are considered critical at global level. Current recovery rates of REEs are very low, below 1 %. Recycling of commercial products is an important part of the circular economy, and is needed to assure adequate handling of discarded appliances, and efficient recovery, and re-use of raw materials. So far, recovery of REEs from materials considered for magnetocaloric refrigeration has not been thoroughly addressed. This paper focuses on this topic, and reports on the potential use of hydrometallurgy to recover REEs from genuine magnetocaloric materials comprising cerium, iron, lanthanum, manganese, and silicon. The investigations target leaching with mineral acid solutions (nitric, hydrochloric, and sulfuric acid), and optimizations of leaching in terms of temperature, acid concentration, and solid-to-liquid ratio. Recovery of the REEs from nitric, hydrochloric, and sulfuric acid leachates was investigated using solvent extraction with three types of solvating extractants: tributyl phosphate, mixed trioctylphosphine oxides, and tetraoctyl digylcol amide. A flowsheet comprising leaching of magnetocaloric materials with nitric acid, and solvent extraction of REEs with trioctylphosphine oxides is discussed.

C.7.2
17:00
Authors : Santiago Cuesta-López, Roberto Iglesias
Affiliations : ICAMCyL Foundation, International Center for Advanced Materials and Raw Materials of Castilla y Leon, 24492, Cubillos del Sil (León), Spain; Department of Physics, University of Oviedo, 33007, Oviedo, Spain.

Resume : The search for sustainable, green and environmentally safe approaches to more efficient and economically viable recycling rates of secondary raw materials from end-of-life (EoL) products is at the forefront of modern waste management scenarios. The scarcity of critical raw materials (CRMs) in Europe represents a major challenge to the green growth, sustainability and clean energy objectives of EU industry. However, many of the most economically important metals are present in EoL products of which there are vast amounts in waste repositories and landfills scattered all over Europe awaiting to be efficiently recycled and subsequently reintroduced back in the supply chain. This work addresses more productive, practical and profitable reprocessing techniques oriented to the recovery of CRMs of interest to the nuclear industry, with an eye to their eventual gradual partial substitution. If fusion energy production is ever to reach the market consumers, the amounts of nuclear industry materials needed to build and maintain fusion reactors worldwide will exponentially grow during the second half of this century. Refractory metals will play a leading role, but also lithium, the only practicable precursor of the very scarce tritium, an essential participant of the Deuterium-Tritium typical fusion reaction. Some of these materials present specific complications concerning their disposal as waste, due to proneness to activation, given the very demanding and extreme environments they face during their work life. Such complications have typically excluded them from novel industrial recycling efforts, leaving aside from the value chain relevant metal resources, that in a raw materials scarcity scenario Europe cannot indeed ignore anymore.

C.7.3
17:15
Authors : Burçak Ebin, Teodora Retegan
Affiliations : Chalmers University of Technology, Chemistry and Chemical Engineering Dept.

Resume : Indium (In) is a crucial raw metal for electronic industry due to its widespread application in electronic boards, solar panels and liquid crystal display (LCD) screens of TVs, laptops, tablets, and mobile phones. Almost 70% of the In in use today is produced for transparent conductive film which is indium-tin-oxide, ITO, for LCD screens. Indium is accepted as one of the scarce material due to its low abundance, and it is in the critical raw materials list for both European Union and US Department of Energy. In this research, recovery of indium from LCD screens by leaching and following separation step were studied. HSC 9 Chemistry software was used for the thermodynamic modeling of the method. The dissolution of the transparent conducting layer from LCD screens were investigated using different acid solutions. Separation of the indium and other valuable metals from leaching solution was studied by solvent extraction and spray pyrolysis methods. Spray pyrolysis method was applied not only for separation purpose, but also to produce fine oxide particles. The separation amount and elemental composition of the powders were analyzed by ICP-OES. The powder properties were characterized by X-ray diffraction and scanning electron microscope.

C.7.4
17:30
Authors : C. Pistidda,a* R. Hardian,a A.-L. Chaudhary,a G. Capurso,a G. Gizer,a H. Cao,a C. Milanese,b A. Girella,b A. Santoru,a H. Dieringa, e K. U. Kainer,e T. Klassen,a M. Dornheim.a
Affiliations : aInstitute of Materials Research, Helmholtz-Zentrum Geesthacht GmbH, Max-Planck-Straße 1, D-21502 Geesthacht, Germany. bPavia Hydrogen Lab, CSGI & Università di Pavia, Dipartimento di Chimica, Sezione di Chimica Fisica, Viale Taramelli, 16, 27100 Pavia, Italy eMagnesium Innovation Centre-MagIC, Institute for Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502 Geesthacht, Germany

Resume : Magnesium has been studied as a potential hydrogen storage material for several decades because of its relatively high hydrogen storage capacity, fast sorption kinetics (when doped with transition metal based additives). This research aims to study the possibility to use waste magnesium alloys to produce good quality MgH2 and Mg containing hydride systems. The production costs of hydrogen storage materials is still one of the major barriers disabling scale up for mobile or stationary application. The recycling of magnesium-based waste to produce magnesium hydride will significantly contribute to the cost reduction of this material. This study focuses on the effect of different parameters such as the use of additives as well as the effect of milling time on the material hydrogenation/de-hydrogenation performances.

C.7.5
18:00
Authors : Didier Zimmermann
Affiliations : EIT Raw Materials, Central co-location Centre

Resume : Innovation is translating smart ideas or inventions into value for society, for instance, in terms of products, businesses, services or improved social organisation. With more than 120 members coming from the 3 sides of the knowledge triangle - universities, research organisations, and industry - the EIT RawMaterials Knowledge and Innovation Community has initiated radical innovation in the critical materials value chains for the benefit of the European society and beyond - from mine to market.

C.7.6
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Magnetic Materials 2 : Benoit Pichon, Daniel Salazar
08:45
Authors : Ester M. Palmero, Javier Rial, Javier de Vicente, and Alberto Bollero
Affiliations : Division of Permanent Magnets and Applications, IMDEA Nanoscience, 28049 Madrid, Spain

Resume : 3D-printing of composite materials is an emergent technology which allows the fabrication of functional structures with complex shapes and potential applications in aeronautics, automotive and energy sectors. Successful application of 3D-printing technologies to permanent magnets (PMs) will open the path to novel and more efficient designs, which will undoubtedly benefit to rare earth-free alternatives. This work focuses on the fabrication of polymerized MnAl-based composites in view of their application in 3D-printing technologies. With this aim, polymerized cold compacted magnets and extruded PM filament have been produced. Gas-atomized MnAl-based particles have been recently processed by the ultrafast milling method achieving high coercivities (4.2-5.1 kOe) in record milling times (30-270 s) [1]. Polymerized magnets and filament have been fabricated from composites (ball-milled MnAl-based particles embedded in a polymer matrix), which were chemically synthesized by solution casting and, subsequently extruded. For the composite with the highest filling factor (86.5% content of magnetic particles), the mixture is homogeneous with the polymer covering the particles [2]. MnAl-based filament (12 m in length) with a filling factor of about 75% and PM properties has been fabricated for the first time [2] to be used in advanced 3D-printing technologies. [1] J. Rial et al., J. Phys. D: Appl. Phys. 50, 105004 (2017). [2] E.M. Palmero et al. Submitted.

C.8.1
09:15
Authors : Sanjeev Kumar Sharma, B. Tiwari, H. R. Prakash, S. Ram, D. Pradhan
Affiliations : Materials Science Centre, Indian Institute of Technology, Kharagpur – 721302, India

Resume : A rare-earth free alloy of an optimized composition Mn0.5Bi0.5 offers high-energy-density ferromagnetic properties useful for devising small magnets and devices for various electronic applications. It is a good example to tailor magnetic properties with high magnetocrystalline anisotropy in the low-temperature phase (LTP). In this investigation, a typical Mn0.5Bi0.5 alloy was prepared in small discs using a standard vacuum arc melting and casting method. The as-obtained alloy disc was crushed into small pieces and further ball milled for 5 h using a high-energy ball mill in refining its nanostructure. An as-prepared powder in this way was annealed at an optimized temperature 300 °C for selective periods of 24, 48, 72 and 96 h in vacuum in optimizing the LTP content. A single crystalline phase is formed in these annealed alloys in terms of the X-ray diffraction patterns. An analysis of the EDX spectra with elemental mapping ensures the Mn and Bi atoms distributed uniformly. HRTEM images studied with SEAD patterns and lattice images reveal truncated LTP-Mn0.5Bi0.5 nanocrystals. The ZFC-FC thermograms were recorded over 5-380 K temperatures at a small 500 Oe field, analysing the induced magnetization of 5-35 % on the spin reorientation point TSR at 105 K in a typical sample annealed for 96 h. The M-H hysteresis loop measures a coercivity of 10.5 kOe (35.0 emu/g magnetization) at 300 K, while 14.5 kOe (30.5 emu/g magnetization) at 350 K in an optimally annealed alloy for 48 h. The results demonstrate a simple technique of producing a rare-earth free alloy with tailored structural and magnetic properties as demanded for developing small magnet devices. Keywords: Permanents magnets, Ferromagnetic alloys, Microstructure, Magnetic properties

C.8.2
09:30
Authors : Anna Lehner, Johannes Möller, Christian Elsässer
Affiliations : Fraunhofer IWM, Freiburg, Germany

Resume : Permanent magnets, such as the state-of-the-art Nd-Fe-B supermagnets, are applied as energy convertors in wind turbines and electric vehicles and are thus key materials for a sustainable energy economy. With the growing global demand for highly performant magnetic materials, it is a formidable challenge to discover and develop new rare earth (RE)-lean hard magnetic phases and thus reduce the dependence on these critical raw materials. In this contribution, we present our computational approach to new hard magnetic phases which feature excellent magnetic properties and a lower RE content than Nd-Fe-B. Complementing our combinatorial high-throughput screening (HTS) of RE-containing intermetallics, we now go beyond identifying promising magnetic phases by modelling microstructure effects on the magnetic properties. For selected RE-intermetallics (e.g. of the ThMn12-structure type) the impacts of atomic rearrangements at surfaces and grain boundaries on the local magnetic properties are presented. Just as for Nd-Fe-B magnets, where great scientific efforts have gone into controlling the microstructure for enhanced magnetic performance, there is a huge potential for optimizing new magnetic phases into highly performant materials. By developing microstructure design criteria we aim at building the rational foundations for an accelerated promotion of promising RE-lean phases to application-ready new hard magnets.

C.8.3
09:45
Authors : Atsufumi Hirohata, Haokaifeng Wu, Tomoyuki Takahashi, Takahiro Ogasawara, Teodor Huminiuc, John Sinclair, Marjan Samiepour, Jun-Young Kim, Gonzalo Vallejo-Fernandez, Kevin O’Grady
Affiliations : University of York; Nagaoka University of Technology; Tohoku University

Resume : In spintronic device applications, the most commonly used antiferromagnet is an IrMn alloy because of its corrosion resistance and high Néel temperature [1]. However, Iridium is a critical raw material as a platinum group metal, which requires the development of an alternative material [2]. Antiferromagnetic layers have been used to pin its neighbouring ferromagnetic layer in a spin-valve read sensor in a hard disk drive and in a magnetic random access memory for example. The magnetic memories are used in extreme conditions, such as in a bonnet of an automobile and in an aeroplane, due to their robustness against temperature and radiation. In this report, recent efforts to replace a widely used Ir-based alloy with a Heusler alloy consists of common elements [3] are discussed. We found a completely disordered phase with X-Y-Z mixing can still exhibit antiferromagnetic behaviour for Mn-based Heusler alloys [2]. Polycrystalline Mn3Ga layers with thickness in the range from 6-20 nm were deposited at room temperature by a sputtering system [4]. Additional ferromagnetic Co0.6Fe0.4 layer (3.3-9 nm thick) capped with 5 nm Ta were subsequently deposited to investigate the exchange-bias behaviour. X-ray diffraction measurements confirm the presence of Mn3Ga (0002) and (0004) peaks characteristic of the D019 antiferromagnetic ordering. The 6 nm thick Mn3Ga film shows the largest exchange bias of 430 Oe at 120 K with a blocking temperature of 225 K. The magneto-crystalline anisotropy for 6 nm thick Mn3Ga thin film sample is calculated to be 9104 J/m3. Such a binary antiferromagnetic Heusler alloy is compatible with the current memory fabrication process and hence has a great potential for antiferromagnetic spintronics. This work has partially been supported by UK-EPSRC (EP/M02458X/1). [1] A. Hirohata and K. Takanashi, J. Phys. D: Appl. Phys. 47, 193001 (2014). [2] A. Hirohata et al., J. Phys. D: Appl. Phys. 50, 443001 (2017). [3] C. Felser and A. Hirohata, Heusler Alloys (Springer, Berlin, 2015). [4] H. Wu et al., J. Phys. D: Appl. Phys. (submitted).

C.8.4
10:00
Authors : Zhenzhen Qin, Guangzhao Qin, Bin Shao, Xu Zuo
Affiliations : RWTH Aachen University; RWTH Aachen University; University of Bremen; Nankai University;

Resume : The Rashba effect, a spin splitting in electronic band structure, attracts much attention for the potential applications in spintronics with no requirement of external magnetic field. Realizing one-dimensional (1D) Rashba system is a big challenge due to the difficulties of growing high-quality heavy-metal nanowires or introducing strong spin-orbit coupling (SOC) and broken inversion symmetry in flexible materials. Here, based on first-principles calculations, we propose a pathway to realize the Rashba spin-split by adsorbing Gd atom on zigzag graphene nanoribbons (Gd-ZGNR) and further investigate the magnetic anisotropy energy (MAE). Perpendicular MAE and unconventional MAE contributions in k-space are found in the self-assembled Gd-ZGNR system, which presents a remarkable Rashba effect (the estimated strength is 1.89 eV Å) due to the strong SOC (~65.6 meV) and the asymmetric adsorption site at nanoribbons edge. Moreover, first-order MAE is connected to the intrinsic Rashba effect beyond the traditional second-order MAE, which is confirmed based on the analysis of electronic structures perturbed with SOC in comparison with metastable Gd-ZGNR at central symmetric adsorption site. The dependence on the ribbon width of first-order MAE as well as Rashba effect in Gd-ZGNRs are also examined. This work not only opens a new gate for designing 1D Rashba system but also provides insight into the unconventional MAE due to the intrinsic Rashba effect, which would be of great significance for searching Majorana fermions and promoting the potential applications in spintronics.

C.8.5
10:15 Coffee Break    
 
TCO & Optics : Patrice Miska, Carlo Ricci
10:45
Authors : S.Aydogan1,2, M.L.Grilli3 and M.Yilmaz2*,
Affiliations : 1Department of Physics, Faculty of Sciences, Atatürk University, 25240 Erzurum, Turkey 2Advanced Materials Research Laboratory, Department of Nanoscience and Nanoengineering, Graduate School of Natural and Applied Sciences, Ataturk University, 25240 Erzurum,Turkey 3ENEA - Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Casaccia Research Centre, Via Anguillarese 301, 00123 Roma, Italy *mehmetyilmaz@atauni.edu.tr

Resume : Over the past few years, indium doped tin oxide has been widely utilized in several optoelectronic devices such as photovoltaic cell, liquid crystal displays and gas sensors because of its unique properties like high conductivity, wide band gap and high electron mobility. However, the main constituent (about 78wt.%) is In which is listed as a critical raw material by EU. Therefore, researchers have been focused on finding out an alternative material to ITO in device applications. Among these effort, the ones based on ZnO has attracted much attention in the past decades due to its suitable and controllable properties for optoelectronic applications. In accordance with this purpose, doping with transition metals has been used to modify and improve the performance of nano materials. In the light of today’s information, it can be said that dopants change the relative characteristics such as structural or morphological properties which affect electrical and optical properties of host materials. Because of this, above mentioned speculation can be seen as a key factor affecting device performance. In this study we conduct our studies on the effect of Co loading on characteristics and device performance of ZnO films prepared by chemical spray pyrolysis technique. Even though also Co is listed among CRMs, its percentage as dopant is very limited (up to 5%).

C.9.1
11:15
Authors : Boyang Che, Dan Zhou, Hui Li, Chaobin He, Xuehong Lu
Affiliations : Energy Research Institute @ NTU, Interdisciplinary Graduate School, Nanyang Technological University, Singapore; School of Materials Science and Engineering, Nanyang Technological University, Singapore; Depeartment of Materials Science and Engineering, National University of Singapore, Singapore

Resume : A polyaniline-Carbon nanotube (PANI-CNT) composite material was used to replace widely used transparent electrode Indium Tin oxide/Polyethylene terephthalate (ITO/PET) in a flexible electrochromic device. By in situ polymerization of aniline with amine-functionalized CNT, a direct conjugation between PANI and CNT can lead to a high electrical conductivity. This electrode has better bendability than ITO/PET electrode due to its polymeric nature. After electrodeposition of electrochromic PANI, the electrochromic performance of the device is competitive to device with ITO/PET electrode. The PANI-CNT electrode can also contribute to the overall performance. After cycles of bending, the sample can still maintain its electrochromic performance. This may be attributed to good conductivity of electrode after bending and well-bonded interface of electrochromic layer and electrode layer as they use the same type of material. All these advantages enable PANI-CNT a better choice of electrode in a flexible electrochromic device.

C.9.2
11:30
Authors : Giacomo Torrisi (1), João Sousa Luis (2) , Olalla Sanchez-Sobrado (2), Manuel João Mendes (2), Hugo Aguas (2), Elvira Fortunato (2), Rodrigo Martins (2), Antonio Terrasi (1)
Affiliations : (1) Università degli studi di Catania, Department of Physics and Astronomy, Via S. Sofia 64-95123, Catania (Italy) (2) i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Universidade NOVA de Lisboa and CEMOP/UNINOVA, Campus de Caparica, 2829-516 Caparica, Portugal

Resume : Transparent contacts are critical materials in devices such as touch screens, LCDs, OLEDs and solar cells. The most used are TCOs made of ITO, with state-of-art electrical and optical properties. However, the cost, availability and toxicity of In is driving the quest for alternative TCOs. Many solutions have been proposed, but only a few of them are reliable and compatible with industrial processes. This is the case of the thin TCO/Ag/TCO multilayer that the authors recently developed with high flexibility, low reflectance and electrical resistance [1]. A step ahead is a similar multilayer but with a Ag mesh instead of a film, with benefits in terms of optical transparency and mechanical flexibility. To this end, we studied innovative IZO/Ag_mesh/IZO structures fabricated via colloidal lithography. Well-defined Ag grids were realized by covering an IZO film with a single layer of polystyrene spheres (1.6 m in diameter) through the Langmuir-Blodgett process. Before the Ag deposition, spheres are partially etched by an O2 plasma, thus controlling the spacing in between. Finally, a capping IZO layer is deposited on top. In this way, we fabricated IZO/Ag/IZO multilayers having different Ag grids in terms of thickness and mesh openings. We found excellent electrical properties and a significant enhancement of the infrared transmittance (Rs=16.4 / and ) with respect to state-of-art transparent electrodes. Results on the optical, electrical and mechanical properties of this family of TCO/metal/TCO hybrid materials is reported and discussed. [1] G. Torrisi et al., Solar Energy Materials and Solar Cells 165, 88-93, 2017

C.9.3
11:45
Authors : Brett Laramee, Junichi Nomoto, Hisao Makino, Tetsuya Yamamoto Valentin Craciun, Catalin Martin
Affiliations : Ramapo College of New Jersey, Mahwah, NJ 07430, USA; Research Institute, Kochi University of Technology, Kochi 782-8502, Japan; Research Institute, Kochi University of Technology, Kochi 782-8502, Japan; Research Institute, Kochi University of Technology, Kochi 782-8502, Japan; Lasers Department, National Institute for Lasers, Plasma and Radiation Physics, Magurele, Bucharest, Romania; Ramapo College of New Jersey, Mahwah, NJ 07430, USA;

Resume : We performed broadband optical reflectance measurements, from 80 cm-1 (~10 meV) to 50,000 cm-1 (~6 eV), on thin films of Ga-doped ZnO (GZO) obtained by ion plating with direct-current arc discharge. The experimental data was reproduced considering reflections at multiple interfaces and assuming a Lorentz-Drude model for both film and substrate, individually. From the fits the main optical functions of GZO were calculated, such as dielectric constant, optical conductivity, reflection or extinction coefficients. Here, we discuss the effects of the deposition parameters, such as the oxygen flow rate and the discharge current between the plasma gun and the source pellet, on optical properties of GZO films.

C.9.4
12:00
Authors : Petr Novák [1], Joe Briscoe [2], Tomáš Kozák [3], Olga Bláhová [1], Pavol Šutta [1]
Affiliations : [1] New Technologies – Research Centre, University of West Bohemia, Plzeň, Czech Republic, e-mail: petrnov@ntc.zcu.cz [2] Materials Research Institute, Queen Mary University of London, Mile End Road, E1 4NS London, UK; [3] Department of Physics and NTIS - European Centre of Excellence, University of West Bohemia, Plzeň, Czech Republic

Resume : ZnO nanorod-based devices have been of increasing interest in the field of flexible electronics, catalyst, optoelectronics and energy harvesting. These devices often contain Zinc oxide film as a seed layer for nanorods and Indium tin oxide (ITO) film as transparent electrode. Since Indium is included in the list of critical raw materials defined by EU commission, the main aims of the present work is the replacement of the preferably-used ITO by an aluminium doped Zinc oxide (AZO) film. The use of polymer flexible substrates usually requires the deposition temperature up to 100 ° C. Moreover, low film thickness is needed to avoid failure of the device due to forming of cracks. Thus the achievement of suitable electrical properties of AZO films deposited on flexible thermally-sensitive substrates is still difficult and therefore it is subject of intense research. In this study, all thin-film depositions were performed using a BOC Edwards TF 600 deposition system equipped with two magnetrons linked to a radio-frequency (RF) and direct current (DC) power supply, which allow to control the oxygen content in the prepared films by co-sputtering from ceramic and metallic target. It was found that the amount of oxygen fundamentally affects the electrical properties of the deposited transparent electrode as well as the seed layer. Various dominant internal defects depending on the different oxygen conditions during the processing was identified as the major reason for these relationships. The control of oxygen amount allows us to achieve lower resistivity of the AZO transparent electrode and also to adjust the seed layer for different types of ZnO nanorod-based devices.

C.9.5
12:30
Authors : Nina Senes (1), Antonio Iacomini (1), Neus Domingo (2), Stefano Enzo (1), Gabriele Mulas (1), Santiago Cuesta-Lopez (3), Sebastiano Garroni* (3)
Affiliations : 1) Department of Chemistry and Pharmacy, University di Sassari, Via Vienna 2, I-07100 Sassari, Italy 2) Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus Universitat Autònoma de Barcelona, Bellaterra, Cerdanyola del Vallès, 08193 Barcelona, Spain. 3) International Research Centre in Critical Raw Materials-ICCRAM, University of Burgos, Plaza Misael Banuelos s/n, 09001 Burgos, Spain

Resume : The developing of lead-free piezoceramics has become one of the most urgent tasks due to the ever-increasing restrictions connected to the use of toxic lead-based materials. In this context, undoped and doped KxNa1-xNbO3 (KNN) systems attracted growing interest as promising candidates due to their excellent piezoelectric properties (390-570 pC/N) by forming new phase boundaries, good electromechanical constants (K33 83%) and high Curie temperature (T 200-420 °C). However, KNN contain 50-55% of Niobium which is considered by the EU as critical raw materials (CRM) with high supply risk. Niobium is in fact expected to have one of the strongest annual demand growths to 2020 among the CRMs. Furthermore, KNN synthesis imposes the use of organic solvents due to the use of alkali elements. To overcome these issues, a new modified Pechini method to synthesize single phase K0.5Na0.5NbO3 powders, from water soluble metal precursors, is presented. The piezo responses of the as calcined systems have been tested by piezoresponse force microscopy (PFM) and compared with similar systems. The piezoelectric coefficient d33 of ~ 80 pm/V, derived by PFM spectroscopy analysis on the local domains, results comparable with the values estimated in the most performing hot-pressed KNN materials, but with the advantage of synthesis at lower temperature and using water soluble precursors.

C.9.6
12:45 Lunch break    
 
EpE Workshop : Jose A. De Toro, Carlo Ricci, Patrice Miska
14:30
Authors : Claire Tutenuite
Affiliations : Entreprises pour l’Environnement

Resume : This mind opening session will focus on providing an overview of global environmental trends likely to impact CRM uses, it will also discuss the issues and levers to be considered and will be followed by an interactive session with the participants. This session is co-organized with EpE, a company-based environmental think tank and platform for expertise.

C..0
15:30 Coffee Break    
16:00 Plenary session    
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Optics & Optoelectronics 1 : Santanu Bhattacharyya, Mathieu Salaun
08:45
Authors : Tetsuo Tsuchiya, Tomohiko Nakajima, Iwao Yamaguchi, Muneyasu Suzuki
Affiliations : National Institute of Advanced Industrial Science and Technology (AIST)

Resume : In order to protect the environment and critical resources of the next generation society, it is necessary to construct an innovative alternative and circulation cycle of the main materials and components of green devices. In this presentation, we will introduce the materials / components for high heat resistant electronic components for SiC power electronics, transparent conductive film, and LED and LED without using Eu, Ru, In. Also, these components for green devices are manufactured using mixture resin or glass of the functional materials. Such a composite material, for example, leads to deterioration in improving luminescence, and makes recycling difficult. In order to solve these problems, we have developed the photo-induced chemical solution deposition such as Photo-assisted metal organic deposition (PAMOD) for developing the new electronic and luminescent components without using glass or resin. In this process, since a phosphor and electronic components (resistor) can be fabricated on a plastic substrate without using a resin, not only excellent properties but also durability and recyclability can be realized. By using PAMOD method, a high brightness white luminescent thin film by using CsVO3 on PET substrate was successfully obtained. The luminescence intensity of the thin film by PRNP is much higher than that of the commercial available one. In addition, YAG:Ce film without resin was developed for LED applications by using photo-assisted MOD. Moreover, Bi2Sr2CaCu2Oy film resistor for SiC power electronics without glass was developed instead of RuO2 and glass. In this talk, we will give a lecture on substitution and recycling of critical raw materials in optoelectronic, power devices components and displays and the new film process that enables energy saving / resource saving.

C.10.1
09:45
Authors : A. Luridiana1 S. Porcu2, A. Cocco1, R. Corpino2, C. M. Carbonaro2, P.C. Ricci2, A. Frongia1, F. Secci1.
Affiliations : 1 Dipartimento di Scienze Chimiche e Geologiche, sp. N8 Km 0.700, Monserrato, CA, 09042 Italy 2 Dipartimento di Fisica, sp. N8 Km 0.700, Monserrato, CA, 09042 Italy

Resume : Nowadays the fluorescent inorganic compounds, based on heavy and light rare earths represent the major emitter materials in lighting applications. Their replacement with inexpensive purely organic compounds offers the possibility to develop cheaper and Critical Raw materials free devices. The thermal and morphologic stability, other than its optical properties, are the basic requirements to been considered as feasible candidate in lighting devices that often limited the use of organic compound. On these basis and taking into account the high thermal stability of the aromatic triazine core and its electron donor and acceptor features, a-amino substituted [1,3,5]-triazine derivatives has been synthetized and their optical properties have been investigated. Further chemical modification has been carried out in order to achieve red shift covering the whole spectral region, without compromising the stability of the emitter material. Thermal gravimetric analysis, solid state NMR, X-Ray Diffraction, time resolved fluorescence spectroscopy cyclovoltammetry allow to evaluate the best candidate for optical application. Finally, we achieved also in the preparation and the characterization of Tb-triazine systems showing the feasibility to use the same organic matrix as host for luminescent ion. These systems with reduced, up to totally free of CRM, represent a reliable phosphors alternative to the actual inorganic rare earth based compounds.

C.10.3
09:45
Authors : H.Jessica Pereira, Joseph Reed, Ross A. Hatton
Affiliations : H.Jessica Pereira; Joseph Reed and Dr. Ross. A. Hatton Department of Chemistry, University of Warwick, CV4 7AL, Coventry, United Kingdom Email: h.pereira@warwick.ac.uk

Resume : Optically thin copper films are attractive as an alternative to silver window electrodes particularly for application in organic photovoltaics, because copper offers comparable electrical conductivity at one percent of the cost. The primary disadvantage of copper is its lower far-field transparency for wavelengths below 550 nm, stemming from intra-band absorptions which do not occur in silver. For wavelengths above 550 nm the transparency is reduced due to reflection, similar to the case of silver. This talk will present a new approach to simultaneously reducing intra-band absorption losses in copper films for wavelengths below 550 nm and dramatically suppressing reflection for wavelengths above 550 nm, based on incorporation of about 100 million tiny circular apertures per square centimeter into the metal film. A potentially low cost approach to achieving such a high density of apertures in a thin metal film will also be described based on spontaneous phase separation in a polymer blend. The advantage of the method presented is that the metal is deposited by simple vacuum evaporation and all subsequent steps are solution based processes using widely available low-cost chemicals based on earth abundant elements. The utility of these nano-structured copper window electrodes will be demonstrated in organic photovoltaic devices.

C.10.4
10:00
Authors : J. Satta, CM.Carbonaro, R. Corpino, D. Chiriu, P.C. Ricci
Affiliations : Dipartimento di Fisica, sp. N8 Km 0.700, Monserrato, CA, 09042 Italy

Resume : Recently, much attention has been paid to the development of new phosphors for lighting application free from Critical Raw Materials, Rare earths in particular. Materials suitable for applications in this field should guarantee a high chemical stability, easiness and green sintering procedure and optimal optical properties. In this framework Calcium Zinc oxysulfide (CaZnOS) represents one of the most promising materials. Not only it provides an excitation channel in the near UV region with broad emission in the visible part of the spectrum (needed to achieve white emission in LED systems), but the long phosphorescence and the mechano-luminescence constitute a prerogative that still needs to be explored. In this work, we report for the first time the optical properties and the kinetics of radiative recombination upon intrinsic and extrinsic excitation from the nanosecond to the millisecond time window. The analysis of time resolved measurements at room and low temperature (down to 10 K) gives new insight on the distribution and nature of the defects that generate the luminescence as well the long phosphorescence upon external stress. The role of the dopant (Mn, Cu but also Tb and Eu) will be discussed and analysed in view of the achievement of novel phosphor with largely reduced amount or totally free of Critical Raw Materials.

C.10.5
10:15
Authors : Seung Hee Choi1, Jung Hyeon Yoo1, Hyun Bin Kim1, Seok Bin Kwon1, Seong Guk Jeong1, Young Hyun Song2 and Dae Ho Yoon1,3*
Affiliations : 1School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon, 440-746, Republic of Korea; 2Lighting Design & Component Research Center, Korea Photonics Technology Institute (KOPTI), Gwangju, 61007, Republic of Korea; 3SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SKKU), Suwon 440-746, Republic of Korea

Resume : Recently, the wide color gamut (WCG) of the white LEDs is an important issue for more realistic colors in displays. Therefore, a number of researches are highly focused in developing high color purity luminescence materials. Organic-inorganic halide perovskite (OIP) nanocrystals (NCs) have attained great attention as the candidates for optoelectronic devices due to their outstanding optical properties such as the wide color tunability, narrow full width at half maximum (FWHM) of emission, high photoluminescence quantum yields (PLQYs) and lower materials and synthesis costs. Owing to the high sensitivity to moisture, temperature, light and air environment of OIP, all-inorganic CsPbX3 (X=Cl, Br, I) NCs have been reported with enhanced stability. In this study, we successfully synthesized the high color purity perovskite NCs with enhanced PLQYs of 99.7% and a narrow FWHM of 21 nm by substituting the Cs cations with Rb cations. As synthesized (Cs0.4Rb0.6)PbBr3 NCs were integrated with mesoporous silica (m-SiO2) matrix. The m-SiO2 significantly improved the thermal- and photo- stability of the perovskite NCs. Furthermore a white LED was designed by combining the perovskite NCs@m-SiO2 composite with red-emitting K2SiF6:Mn4 phosphor on blue InGaN LED. The white LEDs showed a wider color gamut of 119% compared with NTSC value.

C.10.6
10:30 Coffee Break    
 
Catalysis 1 : Dinh Khang
11:15
Authors : Svetlana Neretina, Eredzhep Menumerov, Robert D. Neal, Robert A. Hughes
Affiliations : College of Engineering, University of Notre Dame, IN 46556, United States

Resume : Leaching is a serious problem when using metal nanostructure catalysts in liquid phase reactions because it leads to the loss of precious metals and a dramatic reduction in catalytic performance. This is a major problem for industrial catalysts with both economic and environmental implications. The leaching of metal species from catalysts makes it difficult to reuse the catalysts in batch reactors and maintain the desired initial performance in continuous flow catalytic reactors. Dr. Neretina’s laboratory has designed and built a custom experimental setup which allows one to access catalyst leaching. The Neretina group has carried out studies showing the detrimental role that dissolved oxygen within an aqueous solution can have on catalytic performance and the degree to which metal catalysts leach through oxidative etching.

C.11.1
11:45
Authors : Figen KADIRGAN, Ozlem UCEL, Ozge ERSAHIN, KADIR KIRAN
Affiliations : Nano Science and Nano Technology Program , Istanbul Technical University, Maslak, Istanbul/Turkey

Resume : Catalytic converters are the devices used for purification of exhaust gases of automobile engines, which allow the simultaneous conversion of unburnt hydrocarbons (UHC), carbon monoxide (CO), and nitrogen oxides (NOx) into harmless carbon dioxide (CO2), water (H2O), and nitrogen (N2). The main reason for the usage of catalytic converter is that the respective compounds shall be eliminated before they are released into the surrounding environment, so as to comply with the emission levels imposed by the legislation. Although the catalytic converters had been launched into the market for a long time ago, the development of sustainable three-way catalysts remains a critical research topic especially for the automotive industry due to the increasingly stringent emission regulations together with the cost and scarcity of precious metals. Platinum based catalysts and Palladium based catalysts are used commonly and successfully in this convertors due to high catalytic activities. However, palladium based catalysts are more appropriate for catalytic converters compared to platinum based catalysts because of the higher catalytic activity and lower cost. In addition, mixing Pd with non-precious metals in composites increases their catalytic activities and decreases the cost due to reduced dosage. Also, reducing size to nano-scale increases the surface area and activity of the material. Thus, in this study Pd/Cu nanoparticles are prepared to use in reduction reactions in catalytic converters which are used in gasoline powered cars. The main problem of the usage of these nanoparticles in three-way catalytic converters is that temperature of the exhaust gases can be reach up to 900 C. This high temperatures negatively affect the performance of the nanostructure. Thus, we have used different carrier substrates that have extremely low thermal conductivities such as aluminum oxide foam or Si aerogel to obtain better stability at high temperatures. Resulting materials are characterized using TEM and XRD.

C.11.2
12:00
Authors : Gwang-Hyeon Nam1,2, Yifu Yu1, Qiyuan He1, Xue-Jun Wu1, Hua Zhang1
Affiliations : 1School of Materials Science and Engineering, Nanyang Technological University 2HealthTech NTU, Interdisciplinary Graduate School, Nanyang Technological University, Singapore50 Nanyang Avenue, Singapore 639798, Singapore

Resume : Tremendous effort has been contributed to the phase-controlled synthesis for inorganic crystals, especially the metallic-phase group-VI transition metal dichalcogenides (TMDs), in which the transition metals are Mo and W, and the chalcogens are S, Se and Te, because of their performance in electrocatalysis and energy storage is much higher than those of their semiconducting counterparts. Notably, the metallic phase TMDs exhibit higher performances in the electrocatalytic hydrogen evolution reaction (HER), and the electrical properties of the group-VI TMDs can be controlled by atomic structures such as 1T (metallic, octahedral structure) and 2H (semiconducting, trigonal prismatic structure) phases. Although several methods have been achieved to prepare the metallic-phase MX2 (M=Mo, W; X=S, Se), it was difficult to avoid from the thermodynamically stable 2H phase or too small lateral size after preparation, severely retarding the research of their properties and applications. Therefore, it is crucial to develop a synthesis method for preparation of metallic-phase MX2 (M=Mo, W; X=S, Se) bulk crystals. Here, we report a synthesis method of metallic-phase 1T'-MoX2 (X=S, Se) bulk crystals with lateral size up to hundreds of micrometers. It has been studied for the distorted octahedral coordination structure (1T') and intrinsic electrical property of 1T'-MoS2 crystals. Importantly, the 1T'-MoS2 can be converted to 2H-MoS2 after thermal treatment and laser irradiation. The results of HER performed in electrochemical microcells demonstrate the crystal phase-dependent HER of MoS2, i.e. the basal plane of 1T'-MoS2 is much more active than that of 2H-MoS2.

C.11.3
12:15
Authors : Sang-Il Choi
Affiliations : Department of Chemistry and Green-Nano Materials Research Center, Kyungpook National University, Daegu 41566, Korea

Resume : A layered β-NiOOH crystal with under-coordinated facets is an active and economically viable non-noble catalyst for the oxygen evolution reaction (OER) in alkaline electrolytes. However, it is extremely difficult to enclose the β-NiOOH crystal with under-coordinated facets due to its inevitable crystal transformation to γ-NiOOH, resulting in the exfoliation of the catalytic surfaces. Herein, we demonstrate {111}-faceted Ni octahedra as the parent substrates which surfaces are easily transformed to catalytically active β-NiOOH during the alkaline OER. Electron microscopic measurements demonstrate that the horizontally stacked β-NiOOH on the surfaces of Ni octahedra has resistance to further oxidation to γ-NiOOH. By contrast, significant crystal transformation and thus the exfoliation of the γ-NiOOH sheets can be observed on the surfaces of Ni cubes and rhombic dodecahedra (RDs). Electrocatalytic measurements exhibit that the β-NiOOH formed on Ni octahedra performs highly enhanced OER durability compared to the Ni cubes, Ni RDs, and the state-of-the-art Ir/C catalysts.

C.11.4
12:30 Lunch break    
 
Catalysis 2 : Neretina Svetlana
14:15
Authors : Khang Ngoc Dinh, Qingyu Yan
Affiliations : Energy Research Institute @ NTU (ERI@N) Interdisciplinary Graduate School Nanyang Technological University Singapore 637553, Singapore School of Materials Science and Engineering Nanyang Technological University Singapore 639798, Singapore

Resume : Highly active and low-cost electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are crucial due to the need for clean and renewable energy. Herein, we report the preparation of porous NiFeV layer double hydroxides (LDHs) grown on Nickel foam (NF) as an efficient bifunctional electrode. The lateral size of the nanosheets is few hundreds nm with the thickness of 10 nm. Among all ratios investigated, the Ni0.75Fe0.125V0.125-LDHs/NF depicts the optimized performance. It displays an excellent catalytic activity with modest overpotentials of 0.23 and 0.12 V, alongside with Tafel slope of 39 and 62 mV/dec for OER and HER, respectively. Also, remarkable durability and stability are observed. Interestingly, with such electrode, a single battery of 1.5 V can drive the water electrolysis, outperforming the state-of-the-art IrO2||Pt and indicating successful water splitting with barely 0.27 V overpotential. The exceptional catalytic activity could be attributed to the synergistically combination of Fe and V in Ni-based LDHs that leads to better intrinsic catalytic activity and higher electrochemical surface area (ECSA). The porous structure of the nanosheets gives enough space for electrolyte penetration and diffusion; as well as provide a higher number of active sites by boosting the accessible ECSA. In addition, the in-situ growth of the hydroxide onto conductive NF benefits the charge transfer, lowering significantly the resistance of the system

C.12.1
14:45
Authors : Indrajit Shown 1*, Satyanarayana Samireddi 1, Li-Chyong Chen 2, Kuei-Hsien Chen 1,2
Affiliations : 1 Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan 2 Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan

Resume : Photocatalytic CO2 reduction to solar fuels by artificial photosynthesis is an attractive and effective research area to solve the energy crisis as well as anthropogenic greenhouse emission problems from CO2 emission. In recent years, it becomes a hot renewable-energy research topic. In the past several years, many semiconductor photocatalysts have been developed for photocatalytic CO2 reduction to hydrocarbons [1,2]. The promising prospect of these semiconductor photocatalyst is far away from the commercial requirement. Thus, it is a great challenge to develop a potential photocatalyst for a high CO2 reduction to solar fuel under visible light. In last few years metal dichalcogenide nanostructures are playing an important role in photocatalysis due to their wide range of optical and electronic properties. Moreover, the high surface area and low charge recombination characteristics of 2D materials can potentially enhance the photocatalyst activity. Among various metal sulfides, SnS2 is a naturally occurred n-type narrow bandgap semiconductor. The narrow bandgap with around 0.19 µm average photocarriers diffusion length and high quantum yield of SnS2 thus possesses two advantages for a good photocatalyst under visible light. Although it has a narrow-band gap, however, the indirect band gap and faster charge recombination remain major challenge in the photocatalytic application. In this work, we propose an in-situ carbon doped SnS2 nanostructure system with limited average lifetime of photo-generated electrons and holes by shortening the diffusion time so that they can reach the reaction sites before losing their energy. In the hybrid system the conductive carbon incorporated into SnS2 provides the opportunities for fast charge transport in the nanostructure with an interconnected planar structure, thus shortening the diffusion time from semiconductor interior to surface reaction sites. The synthesized carbon doped SnS2 photocatalyst shows selective photocatalytic CO2 reduction to acetaldehyde with moderately high photochemical quantum efficiency (QE-0.7%) under visible-light irradiation [3]. The details photocatalytic performance, quantum yield, product selectivity of solar chemicals and theoretical study will be discussed on the presentation. References: [1] H-C. Hsu, I. Shown et al.Nanoscale 5, 262, (2013). [2] I. Shown, H-C. Hsu et al. Nano Letters 14, 6097, (2014). [3] I. Shown, S. Samireddii et al. Nature Communications, 9, 169, 2018

C.12.2
15:00
Authors : S. Porcu1 , A. Cocco2, , A. Luridiana2, CM.Carbonaro1, R, Corpino1, D. Chiriu1, F. Secci2, P.C. Ricci1
Affiliations : 1 Dipartimento di Fisica, sp. N8 Km 0.700, Monserrato, CA, 09042 Italy 2 Dipartimento di Scienze Chimiche e Geologiche, sp. N8 Km 0.700, Monserrato, CA, 09042 Italy

Resume : The environmental treatment and clean energy production represents one of the most hard challenge in the next future and the photo-catalysis represent a reliable promising solution. A part the well-known inorganic semiconductors already utilized, titanium dioxide and zinc oxide, the next step is represented by organic photocatalytic materials, that are in general cheaper, more versatile in chemical and in the flexible designs. However most of them are organometallic complexes, where the ruthenium and iridium are the catalytic metallic centres. The substitution of such materials is mandatory in terms of Critical Raw Materials and for low environmental impact. In this work we propose novel Perylene tetracarboxylic diimide’s (PTCDI) -based hybrid materials for photocatalytic applications. PTCDI is characterized by an excellent photochemical and thermal stability other than high molar absorptivity. The coupling with electron acceptor materials, like TiO2 and/or organic, like 7,7 8,8 tetracyanoquinodimethane (TCNQ) give rise to intriguing hybrid materials with increased photo-catalytic properties. In this work, we present the preparation of novel organic PTCDI-based hybrid materials and their structural, morphological, optical and photocatalyitic characterization. 1H-NMR, 13C-NMR, solid state NMR, high resolution mass spectrometry, X-Ray diffraction, UV, time resolved and steady time photoluminescence, infrared and Raman spectroscopy measurements will be provided and discussed.

C.12.3
15:15
Authors : H. El Masaoudi, B. Jaber, A. Laghzizil , M. Benaissa
Affiliations : 1 LaMCScI, Faculty of Sciences, Mohammed V University, Rabat, Morocco 2 Materials Science Platform, UATRS Division, CNRST, Rabat, Morocco 3 Laboratoire de Chimie-Physique Générale, Faculty of Sciences, Mohammed V University, Rabat, Morocco

Resume : Solar energy is one of the most promising technologies due to its potential applications in solving the issues of environmental pollution. Much effort has been focused to study the semi-conductor photocatalysis, which utilizes solar energy to decompose various organic contaminants in waste water. An important example is the Ag3PO4 photocatalyst, which possesses high visible-light photocatalytic activity in O2 evolution and organic contaminant degradation, but the large crystallite size severely limit its practical application. It is highly desirable to expand new photocatalytic Ag3PO4 systems with a nanosized structure, in order to increase the specific surface areas, and to obtain a high photocatalytic activity. In this study, a novel nanosized Ag3PO4 photocatalyst was prepared by Sol Gel method. The products were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) to examine the crystal structure, size and morphology. Fourier transform infrared spectra (FT-IR) have served to characterize and identify the functional groups of the powders while UV-visible spectroscopy for the study of optical properties. Solar energy is one of the most promising technologies due to its potential applications in solving the issues of environmental pollution. Much effort has been focused to study the semi-conductor photocatalysis, which utilizes solar energy to decompose various organic contaminants in waste water. An important example is the Ag3PO4 photocatalyst, which possesses high visible-light photocatalytic activity in O2 evolution and organic contaminant degradation, but the large crystallite size severely limit its practical application. It is highly desirable to expand new photocatalytic Ag3PO4 systems with a nanosized structure, in order to increase the specific surface areas, and to obtain a high photocatalytic activity. In this study, a novel nanosized Ag3PO4 photocatalyst was prepared by Sol Gel method. The products were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) to examine the crystal structure, size and morphology. Fourier transform infrared spectra (FT-IR) have served to characterize and identify the functional groups of the powders while UV-visible spectroscopy for the study of optical properties.

C.12.4
15:30 Coffee Break    
 
Optics & Optoelectronics 2 : Tsuchiya Tetsuo, Carlo Ricci
16:00
Authors : Santanu Bhattacharyya, Florian Ehrat, Alexander S. Urban, Jacek K. Stolarczyk, Jochen Feldmann
Affiliations : Chair for Photonics and Optoelectronics, Department of Physics and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Amalienstr.54, 80799 Munich, Germany

Resume : Carbon dots (CDs) are a versatile nanomaterial with attractive photoluminescent and photocatalytic properties. Here we show that these two functionalities can be easily tuned through simple synthetic means. The CDs were synthesized from citric acid by a microwave irradiation approach, with a varying concentration of nitrogen-containing branched polyethyleneimine (BPEI). The amount of the precursor determines the overall level of nitrogen incorporation and the different inclusion modes within the aromatic domains inside the CDs. At intermediate levels of BPEI, numerous sp2 domains grow with nitrogen in a predominantly graphitic configuration, yielding a high photoluminescence yield. On the other hand, at high (and very low) BPEI content, the nitrogen atoms are located primarily at the edge sites of the aromatic domains. In this form, they attract photogenerated electrons, allowing for an efficient charge separation and an enhanced photocatalytic activity for hydrogen generation from water. The ensuing ability to achieve a controlled trade-off between emissive and photocatalytic behavior of CDs depending on nitrogen atom positioning inside the aromatic domain is expected to bring substantial improvements on their efficiency for on-demand light emission or energy conversion applications. Ref: 1) Nature Communications 8 (1), 1401 (2017) 2) Nano Letters 17 (12), 7710–7716 (2017) 3) Nano Letters 15 (9), 6030-6035 (2015)

C.13.1
16:30
Authors : M. Salaün (1), I. Gautier-Luneau (1), M. Bardet (2), V. Maurel (3), A. Sontake(4), B. Viana (4), A. Ibanez (1).
Affiliations : (1) Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France ; (2) Univ. Grenoble Alpes, CEA, CNRS, INAC, MEM, F-38000 Grenoble, France; (3) Univ. Grenoble Alpes, CEA, CNRS, INAC, SyMMES, F-38000 Grenoble, France; (4) PSL Research University, Chimie ParisTech - CNRS, Institut de Recherche de Chimie Paris, 75005 Paris, France

Resume : Solid-state lighting (SSL) using light emitting diodes (LEDs) is recognized as a major disruptive technology expected to dominate the public lighting market. The main advantages of SSL sources are the energy saving, their potential stability to produce long lifetime devices and their possibility to develop smart lighting devices. At Néel Institute, we develop a new type of phosphors based on metal aluminum borate powders without any lanthanide as doping. The innovation of these phosphors is to produce broad emission bands extended in the whole visible range from emitting centers (structural defects) trapped in stable glassy grains of a few microns in diameters. Thus, from only one phosphor excited with a near-UV LED chip (365- 390 nm), we can generate intense warm white-light: internal quantum yields around 80-90% and very high color rendering indexes (CRI = 92-94). The main objective of this study was to optimize the chemical compositions, synthesis procedures and thermal treatments for these micrometric powders to enhance their photoluminescence properties. This has been favored by the great versatility of “chimie douce” process such as polymeric precursor methods. Complementary spectroscopic studies (EPR, NMR, FTIR, PL) and structural methods (X-ray Diffraction, Pair Distribution Functions (PDF), coupled with thermal analyses (DSC, DTA, TG-MS) have been used to specify the chemical nature and structural environment of emitting centres.

C.13.2
17:00
Authors : Carlo Maria Carbonaro (1), Rossella Delpiano (2), Pier Carlo Ricci (1), Daniele Chiriu (1), Andrea Salis (2), Maria Francesca Casula (2), Riccardo Corpino (1).
Affiliations : 1 Department of Physics, University of Cagliari, Campus of Monserrato, sp n8, km 0.700, Monserrato, Italy 2 Department of Chemical and Geological Sciences and INSTM, University of Cagliari, Campus of Monserrato, sp n8, km 0.700, Monserrato, Italy

Resume : Novel fluorescent nanoarchitectures are investigated to engineer organic-inorganic hybrids for applications in photonics, in particular as white LED. The selected fluorescent compounds are Carbon-dots (CDs) whose emission properties can be tuned by quantum confinement and surface functionalization. The fluorescent quantum yields of C-dots in the blue/green range is almost competitive to those of CdSe/ZnS, and the efficiency in the red/IR range could be increased by proper functionalization of the CDs surface. To achieve photonic applications the fluorescent compounds will be embedded in suitable matrices, such mesoporous silica. The chosen host matrix is mesoporous silica because its huge specific surface area allows hosting large concentrations of fluorescent CDs. The analysis of the interaction of CDs with the matrix, in terms of physical and chemical confinement of emitting compounds, is a strategic issue to fill the current knowledge gap about CDs in embedded systems. Structural and optical properties of Carbon dots prepared by facile microwave thermal synthesis and embedded in sol-gel prepared silica matrix are reported. The hybrid structures promotes the emission in the green region, thus envisaging possible applications of these compounds in the lighting field.

C.13.3
17:15
Authors : Seok Bin Kwon1, Seong Guk Jeong1, Seung Hee Choi1, Jung Hyeon Yoo1, Hyun Bin Kim1, Young Hyun Song3 and Dae Ho Yoon1,2*
Affiliations : 1 School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon, 440-746, Republic of Korea; 2 SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SKKU), Suwon 440-746, Republic of Korea; 3 Lighting Design & Component Research Center, Korea Photonics Technology Institute (KOPTI), Gwangju, 61007, Republic of Korea

Resume : Solid state laser lighting, which combines a laser diode (LD) with a YAG:Ce3 phosphor have been attracted as next-generation light source due to their remarkable characteristics such as environmental-friendly device, long operating time, low energy-consumption and high brightness, compared to conventional light source. For application in solid state lighting phosphors can be designed into various types of packages. For laser-based automotive headlamps, phosphor converters with enhanced stability at high power light energy, is required. Among the various converter types, polycrystalline phosphor plates have better thermal properties than packages using polymers or binders. Particularly in phosphor plates a number of factors including density, grain size, porosity and etc. control the output optical characteristics. These factors can be controlled by using pore forming agent, sintering aid, and precursor. In this study, the YAG:Ce3 ceramic phosphor plates (CPP) were prepared under various conditions, such as amounts of sintering aid, sintering temperature, sintering atmosphere and manufacturing process. We observed the particle size, pore size, yellow ring, density of the fabricated plates, and also compared the optical characteristics difference through laser diode packaging. The sintering temperature and sintering aid content were optimized and the yellow ring was improved by optimizing the precursor and process conditions.

C.13.4
17:30
Authors : S. Siol, M. González-Castaño, N. Ott, V. Araullo Peters, Y. Unutulmazsoy, P.Schmutz, L.P.H. Jeurgens, C. Cancellieri
Affiliations : Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, Dübendorf CH-8600, Switzerland

Resume : TiO2 and WO3 are two of the most important earth-abundant materials for electronic and energy applications. Particularly for smart windows, WO3 is one of best performing materials to date. It has been demonstrated that alloying WO3 with TiO2 can improve both performance and stability of such electrochromic devices[1]. While the oxidation of both W and Ti has been discussed in literature, only few works exist on the oxidation of W-Ti alloys. In this work we present an in-depth study of the oxidation behavior in W-Ti alloys using different synthesis routes. Solid solution alloy precursors were deposited using combinatorial sputtering and subsequently oxidized using either thermal oxidation or potentiostatic anodization, which correspond to near-equilibrium and off-equilibrium growth methods, respectively. The oxide formation during thermal oxidation and the thermal stability of the anodic oxide alloys were monitored using real time synchrotron XRD. For both oxidation methods a Ti-enrichment in the surface region of the grown WxTi1-xOy layer is observed, which strongly depends on the oxidation conditions and precursor composition. As evidenced by XPS mapping and TEM, a thin TiO2 overlayer on top of the WxTi1-xOy film can be achieved, resulting in an increased stability in reactive environments. In addition, the optoelectronic properties of the oxide are reported, providing insights into the synthesis-property relationship of WxTi1-xOy. [1] Sol.Energ.Mat.Sol.Cells 125,184-189,2014

C.13.5
17:45
Authors : S. Marenkin, A. Aronov, I. Fedorchenko, O. Rabinovich, S.. Didenko
Affiliations : Russian Academy of Science. Institute of General and Inorganic Chemistry, Moscow, Russia National University of Science and Technology MISIS, Moscow, Russia

Resume : Cadmium germanium arsenide is an interesting compound due to its outstanding properties for nonlinear optical application. The quality of the crystals has a substantial impact on the output characteristics of the devices. It was discovered Cd3Ge2As4, which is a new metastable phase in the Cd-Ge-As compound alloys. It belongs to the Cd-GeAs2 pseudo-binary section, the same as CdGeAs2. The formation of tricadmium digermanium tetraarcenide from the quenched CdGeAs2 stoichiomentic solution is reported in the present paper. The samples were studied by X-ray diffraction, differential thermal analysis (DTA) and scanning electron microscopy (SEM) with energy dispersive X-ray microanalysis. As the crystallization rate increased, the formation probability of a metastable phase increased, too. The Cd3Ge2As4 phase annealing led to double and triple stable eutectic compositions Cd3As2-CdGeAs2 42.2 at.% Cd, 15.7 at% Ge, 42.1 at.% As and Cd3As2-CdGeAs2-CdAs2 - 42.7 at% Cd, 15.1 Ge and 42.2 at.% As, the formation correspondently.

C.13.6

No abstract for this day


Symposium organizers
José A. DE TOROUniversidad de Castilla-La Mancha (UCLM)

Departamento de Física Aplicada & IRICA EIA, Ronda de Calatrava 7 13071 Ciudad Real Spain

+ 34 655 809482
joseangel.toro@uclm.es
Patrice MISKAUniversity of Lorraine

Jean Lamour Institute, FTS boulevard de Aiguillettes, 54510 Vandoeuvre les Nancy, France

+33 (0)3 83 68 48 27
patrice.miska@univ-lorraine.fr
Pier Carlo RICCIUniversità di Cagliari

Dipartimento di Fisica Complesso Universitario di Monserrato S.P. Monserrato-Sestu Km 0,700 I-09042 Monserrato (CA) Italy

+39 0706754821
carlo.ricci@dsf.unica.it