2020 Spring Meeting
Electronics, magnetics and photonicsZ
Substitution & recycling of critical raw materials in optoelectronic, magnetic & energy devices III
Following the successful editions in 2016 and 2018, the Symposium is devoted to academic and industrial partners working on the substitution and recycling of critical raw materials (CRMs) 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.
Raw materials are the basic, but fundamental, elements for a wealth of current technological applications. However, some of these materials (14 elements) have been defined since 2011 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. This list has been updated to up to 27 elements in 2017.
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, caloric materials), 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 alternative 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 and intersectoral 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.
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 and Recovery/Recycling of CRMs for:
- Transparent conductive layers
- Rechargeable batteries
- Phosphors for LED applications, Scintillators, Displays
- Solar: photovoltaics, photocatalysis, hydrogen production
- Smart windows
- Caloric Materials for energy harvesting or efficient cooling
- Exchange-coupled nanocomposite magnets with less or no rare earths
- New RE-free/lean highly anisotropic magnetic materials
- New and energy efficient motors and generator technologies which do not depend on permanent magnets
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Catalysis : Mihaela Girtan
Authors : Iakovos Yakoumis, Anastasia-Maria Moschovi, Anthi-Maria Sofianou, Ekaterini Polyzou
Affiliations : MONOLITHOS Catalysts & Recycling Ltd.
Resume : The continuously stricter environmental regulations in the transportation emissions sector leads to an increase in noble metals (Pt, Pd, Rh) content in three-way catalytic converters, widely used in gasoline-fueled vehicles and thus, to a gradual increase in their supply and demand deficit. Consequently, noble metal prices rise resulting in an increase in the cost of three-way catalytic converters. A novel low-cost catalyst is described herein for the abatement of the three toxic pollutant gases present in exhaust gases of gasoline-fueled vehicles: CO, NOx and CxHy. The catalyst comprises mainly copper (Cu) substituting at least by 67% of the Platinum Group Metals contained in commercial automotive catalysts. The catalyst is supported over mixed metal oxides comprising cerium oxide (CeO2) doped, stabilized, combined and mixed with ZrO2, said support exhibiting high oxygen storage capacity and elevated specific surface area. Comparative catalytic activity measurements between the proposed catalyst and a commercial noble metal -containing catalyst with high metal loading, have shown the high yield and commercial exploitation potential of the proposed herein catalyst either as fresh or after ageing.
Authors : Motonori Watanabe
Affiliations : International Institute for Carbon-Neutral Energy Research (I2CNER) , Kyushu University, Japan
Resume : Since sunlight can be used as a future light source, it is necessary to construct a system that efficiently transfers charges to the reaction site using visible light, which has 47% of the energy required for the photolytic decomposition of water. One of the approaches for this issue is introduced visible responsible range by organic dyes into photocatalyst, called dye-sensitized photocatalyst. Because these anchor sites can be hydrolyzed under the dye-sensitized type photocatalytic reaction conditions, the photocatalytic activity is only maintained for a period of 10?20 h. We have developed the pyridyl anchored type photocatalytic system for stable dye-sensitized type photocatalyst. The pyridyl groups are a potential candidate to serve as an effective anchor group for the metal oxide surfaces in the dye-sensitized solar-energy conversion systems. This type of anchor group can coordinate with the metal oxide by hydrogen bonding coordination. As a result, pyridyl group coordinated molecules showed higher stability activity for photocatalytic hydrogen production in water medium under visible light (over 100 h) . Here, we would like to report new pyridyl anchored type dye-sensitized photocatalytic hydrogen production. Boron-dipyrromethene (BODIPY) are compounds with specific absorption at 600-700 nm. We have successively introduced on the surface of TiO2 photocatalyst for dye-sensitized photocatalyst. As a result, these dyes modified photocatalysts showed stable visible light driven photocatalytic hydrogen production activity over 100 h and showed as high as 0.8% apparent quantum efficiency at 650 nm with BODIPY dye-modified TiO2 photocatalyst.
Authors : S. Cosentino1, M. Urso1, S. Battiato1, F. Priolo1, A.Terrasi1 and S. Mirabella1
Affiliations : 1 IMM-CNR and Dipartimento di Fisica e Astronomia ?Ettore Majorana?, Università di Catania, via S. Sofia 64, 95123, Catania, Italy
Resume : Hydrogen production through solar-water splitting can be a viable solution towards a more environment-friendly energy economy. Such technology suffers from the cost of the catalysts, being Pt and RuO2 or IrO2 the reference materials used for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Here, we report on a low-cost approach to synthesize Ni(OH)2 nanowalls (NW) acting as efficient catalyst for OER. Working electrodes were fabricated by growing thin films (< 0.2 µm) of Ni(OH)2 NW by combining chemical bath deposition and post-growth surface oxidation. We systematically studied the morphology and chemical arrangement before and after OER through SEM-EDX analysis, while the catalyst loading, its chemical composition and the presence of dopant impurities have been investigated by Rutherford backscattering spectrometry (RBS) and XPS. Electrochemical measurements were performed to study the OER catalytic activity under alkaline conditions (1M KOH). We optimized the synthesis up to get a significant improvement in the OER performance, with a long-term stable overpotential down to 320 mV at 10 mA/cm2 and a O2 turnover conversion frequency up to 0.1 s-1, by employing NiO NW. Such values can be further improved when an additional dopant (like Fe or Co) is added. Our findings confirm how such facile synthesis of NiO/Ni(OH)2 NW can be employed as a viable low-cost method to create efficient platform catalysts, without the use of critical raw materials.
Authors : Fuxi Bao, Erno Kemppainen, Iris Dorbandt, Radu Bors, Rutger Schlatmann, Roel van de Krol, Sonya Calnan
Affiliations : PVcomB, Helmholtz-Zentrum Berlin
Resume : Effective water splitting via electrolysis driven by renewable energy requires highly active catalysts to minimise the sensitivity of the hydrogen (H2) generation rate to fluctuating operating conditions . NiMo can potentially replace platinum as hydrogen evolution reaction (HER) catalysts because of their low overpotential over the entire pH range. However, it is still not understood if the low HER overpotential is due to high intrinsic catalytic activity or extrinsic factors, such as increased surface area or mass loading. We used electrochemical impedance spectroscopy to study HER kinetics of NiMo electrodeposited on fluorine-doped tin oxide glass in alkaline, neutral and acidic media. The higher HER activity in acidic media was found to be accompanied by more favorable H2 adsorption and charge transfer kinetics compared to those in neutral and alkaline media. While two Tafel regions were observed for acidic and neutral media, only one was observed for alkaline media . Preliminary data from fitted impedance spectra indicated that in low overpotential regions (|?|< ~0.15 V for acidic and |?|< ~0.10 V for neutral ), the HER catalysis is mainly governed by H2 adsorption kinetics, while in high overpotential regions it is controlled by charge transfer kinetics. Experiments on the effects of surface roughness, catalyst thickness and electrolyte stirring on HER kinetics are ongoing to confirm intrinsic catalytic properties in different pH regions.
Authors : Alessandro Pira (1), Alberto Amatucci (1) Elisa Pinna (1) Annalisa Vacca (2), Claudio Melis (3), Guido Mula (1,*)
Affiliations : 1.PoroSiLab, Dipartimento di Fisica, Università degli Studi di Cagliari, Cagliari, Italy 2. Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali, Università degli Studi di Cagliari, Cagliari, Italy 3. Dipartimento di Fisica, Università degli Studi di Cagliari, Cagliari, Italy *Corresponding author e-mail address: firstname.lastname@example.org
Resume : To build new environmental-friendly materials, improved strategies and detailed control of the fabrication processes are required. For porous materials, pore size affects both pore filling and filling materials properties. Here we studied porous silicon (PSi) /eumelanin interfaces and show the effect of the pore diameter on the water molecules diffusion within the filled pores. In a recent work, we showed that eumelanin density increases up to 5 nm away from the silicon interface  and showed its effect on the hybrid interface stability. In this work, the PSi layers were prepared using the Electrochemical NanoLithography, a process developed in our laboratory to ensure a controlled pore size distribution . We demonstrate that eumelanin in thin pores shows properties significantly different from its bulk properties, and that these properties are restored with larger pores. We also show, in the case of eumelanin, that a significant improvement of the photogeneration lifetime (from days to months) can be achieved by a control of H2O2 and H2O diffusion. This kind of study also opens the way to the understanding of chemical species mobility in polymers inserted within nanoscale pores by using porous silicon as a sensor of the polymer properties. Work partially supported by Regione Autonoma della Sardegna project CRP78744 ?EnAPSi: Energy applications with porous silicon? 1. Antidormi, A. et al. J. Phys. Chem. C 2018, 122, 28405 2. Pinna, E. et al. Materials 2019, 12, 2891
Authors : Freitas, W.*(1), D?Epifanio A. (1), Placidi, E. (2), Arciprete, F. (3), Mecheri, B. (1). * lead presenter
Affiliations : (1) Department of Chemical Science and Technologies, University of Rome Tor Vergata, Rome, Italy. (2) Department of Physics, Sapienza University of Rome, Rome, Italy (3) Department of Physics, University of Rome Tor Vergata, Rome, Italy
Resume : Platinum group metal-free electrocatalysts have shown promising features for catalyzing oxygen reduction reaction (ORR) at the cathode of different types of fuel cells [1-3]. However, high costs for synthesis, stability and activity issues under operating conditions, still limit their applicability. We propose a facile synthesis strategy to obtain Fe-N-C ORR catalysts consisting on a nitrogen and iron wet impregnation of carbon black followed by pyrolysis steps. Three different nitrogen sources (dopamine, imidazole and benzimidazole), and two different pyrolysis atmospheres (Ar and NH3) were used. The obtained materials were characterized in terms of structure, morphology, surface chemistry, thermal and electrochemical properties. Tailoring the synthesis parameters allowed obtaining electrodes with a high porosity and density of active sites to boost catalytic towards ORR in alkaline environment, as indicated by X-ray photoelectron spectroscopy, cyclic and linear sweep voltammetry with rotating disk electrode. In particular we found that the pyrolysis step under ammonia flow led to high double layer capacitance electrodes with high porosity and the use of imidazole as nitrogen-rich organic precursor improved ORR activity as compared to control Pt-based electrodes. References 1. Thompson et al. Nat Catal, 2019, 2, 558. 2. Mecheri et al, Appl Catal B-Environ, 2018, 237, 699. 3. Artyushkova et al. ACS Appl. Energy Mater. 2019, 2, 5406.
Magnetic coupling and Magnets : Vladimir Popov
Authors : Villanueva, M. (1), Sánchez, E. H. (2), Pedraz, P. (1), Olleros, P. (1), Normile, P. S. (2), Navío, C. (1), Camarero, J. (1,3), De Toro, J. A. (2)*, Bollero, A. (1)
Affiliations : 1 Division of Permanent Magnets and Applications, IMDEA Nanoscience, Madrid, Spain. 2 Instituto Regional de Investigación Científica Aplicada (IRICA) and Departamento de Física Aplicada, Universidad de Castilla-La Mancha, Spain. 3 Condensed Matter Physics Department, Autónoma University of Madrid, 28049, Madrid, Spain.
Resume : The low temperature phase (LTP) of MnBi, with hexagonal crystal structure, is receiving increasing attention due to its high magnetic anisotropy (1.6 MJ/m3) and Curie temperature (711 K), as well as to the outstanding increase in coercivity with temperature, which makes it ideal for high temperature permanent magnet applications, including microscale sensors and energy harvesters. LTP-MnBi microcrystals of different size have been prepared as hexagonal islands on glass substrates by RF-magnetron sputtering of composite targets. Atomic force microscopy shows crater-like shapes, with the outer parts about one order of magnitude thicker than the central zone ( 0.2 m). The microcrystals exhibit perpendicular magnetic anisotropy with coercive fields (up to HC = 10.7 kOe) dependent on the substrate temperature during deposition (TD). At higher TD (475 K), the morphology of the LTP-MnBi microdeposits changes to rods lying on the substrate plane, which display in-plane anisotropy with a remarkable coercivity of HC = 20 kOe at T = 400 K. Finally, ongoing efforts on the utilization of the above LTP-MnBi as a matrix to embed high saturation magnetization FeCo nanoparticles (in order to enhance the energy product through exchange-coupling) will be presented. These soft particles are pre-formed by gas-phase condensation in an ancillary chamber and then injected as a beam into the main chamber, where they are co-deposited with the MnBi matrix.
Authors : Verónica Salgueiriño
Affiliations : Universidade de Vigo
Resume : Nanocrystals of magnetic materials can show interesting behaviors stemming from the combination of chemistry and magnetic performance, which also determines or directs their final purpose. Different examples of magnetic nanocrystals of transition metal oxides, synthesized and manipulated by wet-chemistry methods, will be detailed describing the magnetic behavior and the possible diversity of the ultimate functionalities (magneto-optical activity, exchange bias, spin dynamics, etc. or heat delivery and magnetic guidance of self-propelled swimmers).
Authors : Pratap Pal 1, Krishna Rudrapal 2, Sudipta Mahana 3, Satish Yadav 4, Tapas Paramanik 1,5, Kiran Singh 4,6, Dinesh Topwal 7, Ayan Roy Chaudhuri 2,8, and Debraj Choudhury 1.
Affiliations : 1 Department of Physics, Indian Institute of Technology Kharagpur, W.B. 721302, India. 2 Advanced Technology Development Centre, Indian Institute of Technology Kharagpur, W.B. 721302, India. 3 Rajdhani College, Baramuda square, Bhubaneswar 751003, India. 4 UGC-DAE consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001, India. 5 Department of Physics, School of Sciences, National Institute of Technology Andhra Pradesh, Tadepalligudem 534101, India. 6 Dr. B.R. Ambedkar National Institute of Technology, Jalandhar 144011, India. 7 Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005, India. 8 Materials Science Centre, Indian Institute of Technology Kharagpur, W.B. 721302, India.
Resume : Simultaneous co-existence of room-temperature ferromagnetism and ferroelectricity in Fe doped BaTiO3 (BTO) is intriguing, as such Fe doping into tetragonal BTO, a room-temperature ferroelectric, results in the stabilization of its hexagonal polymorph which is ferroelectric only below ~80K. Here, we investigate its origin and show that Fe doped BTO has a mixed-phase room-temperature multiferroicity, where the ferromagnetism comes from the majority hexagonal phase and a minority tetragonal phase gives rise to the observed weak ferroelectricity. In order to achieve majority tetragonal phase (responsible for room-temperature ferroelectricity) in Fe doped BTO, we investigate the role of different parameters which primarily control the paraelectric hexagonal phase stability over the ferroelectric tetragonal one and identify three major factors namely, the effect of ionic size, Jahn-Teller (J-T) distortions and oxygen-vacancies, to be primarily responsible. The effect of ionic size which can be qualitatively represented using the Goldschmidt's tolerance factor seems to be the major dictating factor for the hexagonal phase stability. The understanding of these factors not only enables us to control them but also, achieve suitable co-doped BTO compounds with enhanced room-temperature multiferroic properties.
Authors : A. Raja, T. Adhikary, G.P. Das, S. Ghosh, D.K. Satapathy, A. Oraon, S. Aich I.A. Al-Omari J.E. Shield
Affiliations : Department of Metallurgical & Materials Engineering, Indian Institute of Technology, Kharagpur-721302, India Department of Physics, P.O. Box 36, Sultan Qaboos University, PC 123 Muscat, Oman Department of Mechanical Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA.
Resume : The effect of Hf and B additions on the phase stability, microstructure and magnetic properties of the metastable SmCo7 (1:7H) ribbons has been investigated with a combined approach of experimental measurements and first principle DFT (density Functional Theory) calculations. A series of (Sm0.12Co0.88)95Hf5-xBx (x=0, 1, 2, 3, 4 and 5) alloys were arc-melted in a TIG (tungsten inert gas) arc melting furnace, followed by melt-spinning onto a copper roller at a wheel velocity of 40 m/s. Characterization based on X-ray diffraction indicates that the major phase is SmCo7 having meta-stable (TbCu7-type) structure. From the total energy calculations using DFT, the phase stability of (Sm0.12Co0.88)95Hf5-xBx ribbons have been confirmed. Moreover, Hf and B addition results in an effective grain refinement; average grain size being as low as ~ 80 nm. The reduction in grain size leads to significant changes (increase or decrease) in magnetic properties depending on the Hf/B ratio. The coercivity value (Hc) varies between 7 kOe and 12 kOe as x (at.% B) increases from 0 to 5 at.%. The experimental coercivity values have been compared with the computed anisotropy energies. The saturation magnetization (Ms) increases from ~54 emu/g to 77 emu/g with increasing B concentration (x).
Magnetocalorics and Energy Harvesting : José Angel de Toro
Authors : J.F. López-Toro, D. Salazar, G.A. Mendoza
Affiliations : Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia; BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940, Leioa, Spain; Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia
Resume : La< sub>1-x< /sub>Dy< sub>x< /sub>Mn< sub>1-y< /sub>Zn< sub>y< /sub>O< sub>3< /sub> system belongs to the family of perovskites-ABO< sub>3< /sub>- and it contains two well-defined magnetic sublattices. In this work, we study the influence of magnetic dilution on the magnetic properties of the system for x = 0.0, 0.05, 0.1 and y = 0.0, 0.05, 0.1 at temperatures between 10 K and 300 K. For the diluted samples, the field-cooled magnetization (MFC) at 10 Oe shows a change of paramagnetic to ferromagnetic order. Below Tc, the large difference between MFC and zero field-cooled magnetization (MZFC) as well as their bifurcation are factors that suggest a glassy behavior. In our case, the measurements suggest an antiferromagnetic inhomogeneous long-range order followed by a canted antiferromagnetic order at lower temperatures. The magnetization results have been correlated by electron magnetic resonance measurements in the temperature range 5 K < T < 300 K
Authors : Suzanne K. Wallace* (1), Anton S. Bochkarev (1), Ambroise van Roekeghem (1), Javier Carrasco (2), Alexander Shapeev (3) and Natalio Mingo (1)
Affiliations : (1) CEA, LITEN, 17 Rue des Martyrs, 38054 Grenoble, France; (2) CIC EnergiGUNE, Albert Einstein 48, E-01510, Miñano, Spain; (3) Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, Nobel St. 3, Moscow 143026, Russia
Resume : Co3O4 is a material of interest for thermochemical solar energy storage, however, it is desirable to alloy this compound with Mn3O4 to reduce the stoichiometric ratio of Co due to the expense of this component. In this work, we use machine learning techniques with moment tensor potentials (MTPs)  and artificial neural networks (ANNs)  to predict the phase stability of CoxMn3-xO4 alloys. The utilisation of machine learning techniques in materials science is enabling the typical time- and length-scale boundaries of density functional theory (DFT) based methods to be pushed further. The total possible configuration space of an alloy is an example of a system that can be too computationally demanding to study exhaustively with DFT methods. However, the energies of all possible configurations are necessary to investigate entropic stabilisation of alloys. Using MTPs and ANNs we are able to predict the energy density of states for the full alloy configuration space of millions of structures, starting from a training set of only hundreds of structures.  A. V. Shapeev, Moment tensor potentials: A class of systematically improvable interatomic potentials, Multiscale Modeling & Simulation14, 1153 (2016).  A. S. Bochkarev, A. van Roekeghem, S. Mossa and N. Mingo, Anharmonic thermodynamics of vacancies using a neural network potential, Physical Review Materials 3, 10.1103/physrevmaterials.3.093803 (2019).
Authors : Philip Murgatroyd, Kieran Routledge, John Claridge, Jonathan Alaria
Affiliations : Department of Physics, University of Liverpool; Department of Physics, University of Liverpool; Department of Chemistry, University of Liverpool; Department of Physics, University of Liverpool
Resume : Recently a computational proxy was developed to identify new magnetocaloric materials whereby first principle structure relaxation is carried out with and without spin polarization to ascertain the degree of magnetic deformation (Chem. Mater., 29, 1613-1622, 2017). By applying this method to ferromagnet in the PbFCl family we found magnetic deformation of around 2% which is similar to other magnetocaloric compounds. We therefore have focused our experimental study on MnZnSb, which is reported to be an itinerant ferromagnet with a second order phase transition and Curie temperature about room temperature (Jap. J. Appl. Phys., 32, 273, 1993). Detailed magnetization measurements were carried out and Arrott analysis yields a Curie temperature of 304K, with the system being described as a 3D itinerant ferromagnet from the critical exponents of the Arrott-Noakes equation. We find a reasonably large magnetic entropy change of 4.5 Jkg-1K-1 with a relative cooling power of 153 Jkg-1; which is comparable to second order compounds with about room temperature transition temperatures. Heat capacity measurement shows an anomaly around the magnetic transition and together with the magnetometry can be used to calculate an adiabatic temperature change of 2 K under 2 T. Temperature dependant powder neutron diffraction was used to investigate the origin of the significant magnetic entropy change around the magnetic transition.
Authors : Bosco Rodriguez, Daniel Salazar, Volodymyr Chernenko
Affiliations : BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940, Leioa, Spain; BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940, Leioa, Spain; BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940, Leioa, Spain & Ikerbasque, Basque Foundation for Science, Bilbao 48013, Spain
Resume : Solid-state refrigeration is considered as a promising alternative to the less efficient conventional gas-compression-expansion refrigeration. Particularly, magnetocaloric (MC) cooling is the most elaborated today method of solid state refrigeration and development of the suitable MC materials is in the core of this field of research. The aim of the present work was to investigate MC materials based on the Heusler type NiCoMnSn metamagnetic shape memory alloys (MetaMSMAs) and explore their potential application for the solid state cooling on macro- and microscales. The alloy composition, facilitating the martensitic transformation near room temperature with low thermal hysteresis, was elaborated. The actual alloy was fabricated by the induction method and casting. The ingot was solution treated at 900? for two hours. Part of the ingot was used to prepare melt-spun ribbons which, in turn, served for easy manufacturing a powder by grinding. The material on each stage was heat treated and characterized magnetically and structurally. MC effect was measured by the magnetic field induced adiabatic temperature change (?T< sub>ad< /sub>). The powder of MetaMSMA was used for room temperature additive manufacturing. As a result, a printable ink exhibiting inverse MC effect (?T< sub>ad< /sub> about 2K in the field of 2T) was created for the first time. The technology now can be used for 2D printing of cooling microdevices for flexible electronics.
Authors : Joris More-Chevalier1, Michal Novotný1, P?emysl Fitl1,2, Martin Hru?ka2, Petr Hru?ka1,3, Ji?í Bulí?1, Ján Lan?ok1
Affiliations : 1 Institute of Physics of the Czech Academy of Sciences, Na Slovance 1999/2, 182 21 Prague, Czech Republic. 2 Department of Physics and Measurements, University of Chemistry and Technology Prague, Technicka 5, 16628 Praha 6, Czech Republic. 3 Charles University, Faculty of Mathematics and Physics, V Hole?ovi?kach 2, 18000 Praha 8, Czech Republic.
Resume : Black aluminium is a metal with a cauliflower surface morphology favouring a moth-eyes effect. A high light absorbance results from these structures explaining the black appearance of these films. Aluminium has the advantage to be cheap and the most abundant metallic element. Black aluminium films were deposited on different subtracts as fused silica, glass, and metallic surfaces, using DC pulsed magnetron sputtering in a mixed atmosphere of argon and nitrogen. Conditions in the N2/Ar mixture in the film growth were studied and black film growth was observed with a nitrogen percentage of 6%. An ultra-high absorbance of 96.6% was measured for a wavelength range from 300 nm to 1100 nm. Black aluminium films presented a metallic behaviour slightly degraded in comparison to aluminium film. Then, these layers were deposited on Quartz Crystal Microbalance (QCM) sensors in order to increase the active surface areas of electrodes. A change of the resonance frequency was reported and a clear improvement in the QCM response was measured. Black aluminum was also deposited on pyroelectric films to convert light energy into heat, and then the heat energy into a pyroelectric current. Large temperature variations induced by the high light absorbance double the polarization variation reported across the pyroelectric samples.
Authors : Ander Reizabal, Carlos Costa, Leyre Perez, Jose Luis Vilas-Vilela, Senentxu Lanceros-Mendez
Affiliations : BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940 Leioa, Spain. Macromolecular Chemistry Research Group (LABQUIMAC), Dept. of Physical Chemistry, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), Spain Center of Physics, University of Minho, 4710-058 Braga, Portugal. Center of Chemistry, University of Minho, 4710-058 Braga, Portugal Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
Resume : The strong dependence of humans on fossil fuels during the last centuries has generated an alarming global environmental damage. In order to change this situation and minimise the caused damage, is proposed the technological transition from synthetic materials toward a new generation of natural based ones. In this aim, we have selected Silk, a natural macromolecular protein produced by Bombyx Mori silkworms as one of the most promising materials. Silk fibers are among the strongest materials obtained from nature and thanks to the extended silkworm breeding are easily accessible. Silk has been naturally endowed with excellent thermal and chemical stability, high mechanical strength and biodegradability. Further, silk is highly processable and some works have reported its piezoelectric response. In order to explore Silk potentiality and contribute to natural based materials transition, this works reports a series of fully functional Silk based devices. For that, Silk original shape was initially modified as fibres, films, mats, membranes, gels and particles. Secondly, obtained new morphologies were combined with complementary fillers in order to improve their intrinsic properties. Thereby, transparent and conductive layers, piezorresistive sensors, magnetic and electric bending responsive actuators and polymeric Li-batteries were obtained. Actually, a full line of functional and active devices have been processed from Silk. Thanks to this advances, is has been demonstrated that really exist a choice for synthetic materials to natural ones transition, approaching us to a future linked with nature and less harmful with our environment.
Poster Session : Daniel Salazar, Maria Luisa Grilli, Valentina Ivanova
Authors : Jing Yang, Jialiang Luo, Fang Wu, Wei Jiang, Xu Qiao
Affiliations : National Special Superfine Powder Engineering Technology Research Center, Nanjing University of Science and Technology, 210094, Nanjing, China; National Special Superfine Powder Engineering Technology Research Center, Nanjing University of Science and Technology, 210094, Nanjing, China; National Special Superfine Powder Engineering Technology Research Center, Nanjing University of Science and Technology, 210094, Nanjing, China; National Special Superfine Powder Engineering Technology Research Center, Nanjing University of Science and Technology, 210094, Nanjing, China; School of Chemistry and Chemical Engineering Nanjing Tech University, 211816, Nanjing, China
Resume : Recycling chlorine resource has caused widespread concern, and the catalytic oxidation process is one effective method. However, hydrogen chloride oxidation is a strong exothermic reaction, and the reaction temperature is difficult to control in the fixed bed reactor. the fluidized bed with the advantage of fast heat moving is adopted in this process. Y molecular sieve-kaolin as support and aluminum sol-silica sol as binder were used to the preparation of CeCuK/Y fluidized bed catalyst, and a suitable two-step preparation process was selected to reduce the sticking to the wall in the spray process. BET, SEM, XRD, Wear index tester were used to characterize the catalyst. Catalyst activity was investigated in a fluidized bed, and under the condition of reaction temperature 430 ℃,volume ratio of hydrogen chloride to oxygen 1:1, space velocity 1.0 h-1, the maximum conversion of hydrogen chloride reached 82%.
Authors : Jialiang Luo, Jing Yang, Fang Wu, Wei Jiang
Affiliations : National Special Superfine Powder Engineering Technology Research Center, Nanjing University of Science and Technology
Resume : In order to obtain a high-performance absorber, the Ce15.6Co81.2-xFe3.2Cux (x=0.0, 1.6, 4.8, 8.0, 11.2) powders were prepared via the method of arc melting and high energy ball milling. The structure, morphology, composition and electromagnetic parameters of the samples were examined by variously analytical techniques. The results of phase structure indicated that the all powders mainly consisted of single phase CeCo5. The morphology of the powders were sheet with high aspect ratio, which was conducive to achieve the excellent absorption performance. The absorption peak frequency of Ce-Co-Fe-Cu powders moved to low frequency in the range of 1.6-2.0 mm and all minimum reflection loss (RL) values were less than -20 dB. For the sample excluding Cu, the minimum RL was -37.35 dB at 11.12 GHz with the thickness of 1.8 mm. At the thickness of 1.9 mm, the minimum reflection loss (RL) value of Ce15.6Co79.6Fe3.2Cu1.6 could reach -34.79 dB at 9.6 GHz. All results suggested that the powders are promising electromagnetic wave absorption materials with a good performance.
Authors : Naoufel Khemiri, M. Kanzari
Affiliations : Université Tunis El Manar, Ecole Nationale d’Ingénieurs de Tunis, Laboratoire de Photovoltaïque et Matériaux Semi-conducteurs, B.P 244, Tunis 2092,, Tunisie. Université de Tunis, IPEITunis Montfleury, Laboratoire de Photovoltaïques et Matériaux Semi-conducteurs-ENIT.
Resume : Since many years, some raw materials used in photovoltaic technology (such as indium, germanium…) were classified as critical which may constitute a serious problem for the perennity of thin film solar cells. In order to ensure the perennity and development of thin film solar cells, we must substitute the classical materials (CIGS, CdTe…) with critical raw materials-free such as Cu2ZnSnS4. Cu2ZnSnS4 and sodium doped Cu2ZnSnS4 (Cu2ZnSnS4:Na) thin films were successfully deposited by vacuum thermal evaporation method. Na concentration varied from 0 to 7 at. %. The effect of Na doping on the optical and electrical properties of the Cu2ZnSnS4 thin films was investigated. The optical, structural and electrical properties were studied using UV-Vis-NIR spectroscopy, X-ray diffraction (XRD) and AC impedance spectroscopy, respectively. The optical properties of Cu2ZnSnS4:Na thin films were calculated the transmittance and reflectance data. With the increase of the Na concentration, the band gap of the films increased gradually from 1.52 to 1.90 eV for sodium doping of 0-7 %. The XRD analysis confirms the existence of Cu2ZnSnS4 phase with the preferential plane (112). Electrical properties have been investigated by AC impedance spectroscopy over a wide range of temperature up to 285 °C starting from room temperature in the frequency range 5 Hz–13 MHz. The complex impedance plots display one semicircle with equivalent circuit functions as typical parallel RC. Cu2ZnSnS4 material could substitute CIGS as a cost-effective and earth abundant absorber in thin film solar cells.
Authors : M. C. Ferrara, S. Mazzarelli, L.Tapfer.
Affiliations : ENEA, Brindisi Research Centre, Strada Statale 7 Appia, 72100 Brindisi, Italy,
Resume : Transparent conducting ceramic films are of high technological interest to replace traditional transparent conducting oxides such as indium-tin oxide (ITO) and F-doped SnO2 (FTO) that are widely used in electrochemistry and in related applications like in dye-sensitized solar cell (DSC). In particular, there is a strong demand for the replacement of ITO and FTO for DSC application owing the thermal instability of ITO and the formation of a Schottky barrier at the heterojunction photoanode interface of TiO2 with both ITO and FTO. Here, we briefly report on the preliminary experimental results of a work-in progress study on the synthesis and characterisation of gold nanoparticles (Au-NPs)-doped titania films obtained by using a sol-gel procedure. Transparent Au-NP-doped and undoped sol gel titania coatings were grown on soda lime glass and (100)-Si-substrates and heat treated in air at 500°C after deposition. The chemical composition, morphology and microstructure of the films was investigated in detail by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and X-ray scattering (XRD and XSR). A four-point probe method was used to measure the sheet resistance of the layers to avoid contact resistance. The results show that the films are free from organic residues and are constituted of nanocrystalline titania (crystallite size about 12nm ) in anatase structure with embedded Au NPs (crystallite size: between 10nm and 20nm). The presence of the Au NPs in the titania matrix gives rise to a sharp lowering of the sheet resistance up to < 20 ohm/sq. This finding suggests that Au-NPs titania nanocomposites could be considered as transparent conductive layers to replace ITO and FTO in order to fabricate electrocatalyst supports for electrochemical applications. However, further studies are necessary and are currently under way in our laboratories.
Authors : H. Bihri1, I. Chaki1, Z.O. Elhmaidi1, W. Belayachi (1,2), L. Atourki1, Z. Edfouf1, F. Cherkaoui El Moursli1, M. Regragui1, Z. Sekkat3, A. Dinia2 and M. Abd-Lefdil1
Affiliations : 1University of Mohammed V of Rabat, MANAPSE, FSR, P.B. 1014, Rabat - Morocco. 2Institut de Physique et Chimie des Matériaux de Strasbourg, Université de Strasbourg, CNRS UMR 7504, 23 rue du Loess, B.P. 43, F-67034 Strasbourg Cedex 2, France. 3Optics & Photonics Center, Moroccan foundation for Advanced Science, Innovation and Research (MAScIR), Rabat, Morocco.
Resume : Structural, optical and electrical properties of (Ytterbium/Terbium) co-doped ZnO thin films deposited on glass substrates by spray pyrolysis method were investigated. The films exhibited the hexagonal wurtzite structure with a preferential orientation along  direction. No secondary phase was observed in the X-ray diffraction detection limit. Atomic force microscopy (AFM) was performed and a root mean squared roughness (RMS) of our samples decreased with Terbium content. Photoluminescence measurements showed a luminescence band at 980 nm that is characteristic of Yb3 transition between the electronic levels 2F5/2 to 2F7/2. This is an experimental evidence for an efficient energy transfer from ZnO matrix to Yb. Hall Effect measurements gave a low electrical resistivity value around 6.0 10-3 Ω.cm. Such characteristics make these films of interest to photovoltaic devices.
Authors : Irinela Chilibon
Affiliations : National Institute of Research and Development for Optoelectronics, INOE-2000 Optospintronics 409 Atomistilor Str., P.O. Box MG-5 77125, Bucharest-Magurele, Romania 4021.457.45.22
Resume : The most common sources of energy available in the environment, frequently used for the extraction of electricity are: wind, solar energy, temperature and stress or pressure. Piezoelectric generators are appropriate to convert the smallest mechanical deformations directly into electrical energy. Piezoelectric materials have the capability to generate a small amount of current, when they are subjected to mechanical pressure, such as pushing, bending, twisting, and turning. A vibrating piezoelectric device differs from a typical electrical power source in that it has capacitive rather than inductive source impedance, and may be driven by mechanical vibrations of varying amplitude. Some structures can be tuned to have two natural frequencies relatively close to each other, resulting in the possibility of a broader band energy harvesting system. The energy produced by piezoelectric materials is in many cases far too small to directly power an electrical device. The progress in the device innovation happens where Microelectromechanical Systems (MEMS) technologies overlap with smart technologies. For intelligent sensor systems this means a trend from miniaturized sensor to the smart and miniaturized sensor systems, which can integrate processing functions in a minimal space. Acknowledgements: The author is grateful for the financial support of Ministry of Research and Innovation (MCI), 2020 Core Program, and Romanian Executive Agency for Higher Education, Research, Development and Innovation Funding (UEFISCDI).
Authors : Sung-Myung Ryu, Chunghee Nam
Affiliations : Department of Photonics and Sensors, Hannam University; Department of Electrical and Electronic Engineering, Hannam University
Resume : Conventional vapor-compression refrigeration technology has practical limitations because of its environmental destruction. Recently, new cooling technologies to replace it have been underway, including thermoelectric cooling, thermoacoustic refrigeration, and magnetic refrigeration, etc. Among them, magnetic refrigeration is based on the thermodynamic magnetocaloric effect (MCE). In this presentation, microwave hydrothermal synthesis was employed to fabricate DyVO4 nanowires as a MCE material for hydrogen liquefaction. During synthesis, EDTA was added as a chelating agent to obtain uniform DyVO4 nanowires (sample A), and their magnetic properties were compared with those of irregular shaped DyVO4.nanoparticles (sample B). The structure and morphology were studied by using scanning electron microscope (SEM) and transmission electron microscope (TEM) measurements. The Neel temperature (TN) of the sample A was higher than that of the sample B due to suppression of antiferromagnetism induced by the size effects of the sample B. The Curie-Weiss fitting showed the weak antiferromagnetism for the both samples. However, the effective magnetic moments for the both samples had lower values than that of bulk DyVO4 because of the size effects, where uncompensated spins on the surface of the nanostructures induce suppression of antiferromagnetism. The maximum magnetic entropy change (-ΔSM) of the sample A was higher than that of the sample B at H = 50 kOe, and consequently led to an increase in relative cooling power (RCP), a measure of MCE. It is known that DyVO4 has a structural transition from tetragonal to orthorhombic symmetry around 14 K due to the Jahn-Teller effect induced by the ordering of quadrupole of Dy3+ ions . The magnetic entropy changes (- ΔS) with temperature showed an anomaly of -ΔS due to the Jahn-Teller effect for the both samples, which was dependent on the strength of the magnetic field. The quadrupole coupling of DyVO4 resulted in an enhancement of RCP due to an increase of the full width of the maximum of temperature.  A. Midya, N. Khan, D. Bhoi, P. Mandal, Physica B, (2014) 448, 43-45.
Authors : Floriana Billeci,(1) Francesca D’Anna,(1) Maria Luisa Grilli,(2) Marta Feroci (3)
Affiliations : (1) Dipartimento STEBICEF – Sezione di Chimica, Università degli Studi di Palermo, Viale delle Scienze, Ed. 17, 90128, Palermo, Italy (2) Energy Technology Department, ENEA, Casaccia Research Centre, Rome, Italy (3) Department SBAI, Sapienza University of Rome, via Castro Laurenziano, 7, 00161 Rome, Italy
Resume : Study on Cobalt-Ionic Liquids interaction to design new thermochromic materials. Floriana Billeci1, Francesca D’Anna*1, Maria Luisa Grilli*2, Marta Feroci3. (1) Dipartimento STEBICEF – Sezione di Chimica, Università degli Studi di Palermo, Viale delle Scienze, Ed. 17, 90128, Palermo, Italy (2) Energy Technology Department, ENEA, Casaccia Research Centre, Rome, Italy (3) Department SBAI, Sapienza University of Rome, via Castro Laurenziano, 7, 00161 Rome, Italy The numerous research studies on Ionic Liquids (ILs) and the disparate fields of applications are based on their well-known advantageous properties. Hence, in this work, a mixture of [bEt3N][NTf2] (solvent) and an IL bearing gluconamide moiety (ligand) were employed in a thermochromic study with Co(NTf2)2.1 Gluconate fragment (therefore multiple hydroxyl groups) in the cation and the bromide anion display interaction with the cobalt salt. This interaction shows a thermochromic octahedral (pink) – tetrahedral (blue) configuration change depending on the temperature. Meantime, from the trend of the absorbance, the temperature of the transition can be determined. The working temperature range (10-100 °C) and, even more, the transition temperature (60 °C) opens the way for the potential application in the thermosensitive devices field.2 In order to make this goal possible, the ratio ligand/metal, the IL used as the solvent and the structure of the IL ligand were taken into account. 1. S. J. Osborne, S. Wellens, C. Ward, S. Felton, R. M. Bowman, K. Binnemans, M. Swadzba-Kwasny, H. Q. N. Gunaratne, P. Nockemann, Thermochromism and switchable paramagnetism of cobalt(II) in thiocyanate ionic liquids. Dalton Trans. 44 (2015) 11286-11289. 2. K. Zhang, M. Zhang, X. Feng, M. A. Hempenius, G. J. Vancso, Switching light transmittance by responsive organometallic poly(ionic liquid)s: control by cross talk of thermal and redox stimuli, Advan Funct Mater 27 (2017), 1702784-n/a. Presentation preferred – Select the appropriate method Poster presentation preferred
Authors : Nayoung Lee1, 2 , Rahman Jamil Ur1, Woo Hyun Nam1, Jung Young Cho1 , Won Seon Seo1, Weon Ho Shin3, Walter Commerell4, Jong Wook Roh2 ,*
Affiliations : 1 Enerygy and Environmental Division, Korea Institute of Ceramic Engineering and Technology, Jinju 52851, Korea 2 School of Nano & Materials Science and Engineering, Kyungpook National University, Sangju 37224, Korea 3 Electronic Materials Engineering, Kwangwoon University, Seoul, 01897, Korea 4 Institute for Energy and Drive Technologies, Technische Hochschule Ulm(THU), Ulm, 89075, Germany (email@example.com)*
Resume : Energy conversion using thermoelectric material have been one of the most challenging method. Epically. Bi2Te3 has been a representative thermoelectric semiconductor with a relatively high electrical conductivity and lower thermal conductivity. The efficiency of thermoelectric materials is generally expressed as figure of merit, ZT = S²σT/κ, where σ is the electrical conductivity, S is the Seebeck coefficient, and κ is thermal conductivity. In order to improve the ZT, various methods such as doping, nano-structuring, or introducing nanomaterials has been researched, which are relatively expensive and complex methods. In this study, we attempted to get lower thermal conductivity by reducing the grain size by using simple and inexpensive milling process. For enhancing the uniformity of the particle size distribution, additional sieving process of Bi2Te3 powder were employed. The milling process decrease particle size of Bi2Te3, leading to reduction of grain size of sintered samples. The reduced grain size causes the more phonon scattering at the grain boundary, resulting in enhancing the ZT in all of milled samples of Bi2Te3. The highest ZT value were measured to be 0.84 at 423 K in the additionally-sieved samples. This result proposes the size and uniformity of the Bi2Te3 powder should be considered as important factors to improve the thermoelectric properties.
Authors : Dong HUANG, Francis Chi-Chung LING, Zhifu Liu
Affiliations : Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China
Resume : Materials having colossal dielectric constant (CDC) and low loss (ε_r≥10^3 and dielectric loss tanδ≤0.1) with good frequency stability is crucial for device miniaturization and high-energy density storage application. Hu et al  recently reported a temperature and frequency independent CDC with a low dielectric loss in acceptor-donor co-doped TiO2. The CDC is postulated to be originated from electron-pinned defect dipoles which is the acceptor-donor defect complex, though the detail mechanism and experimental evidence are lacking. Li-Al co-doped ZnO, Zn0.99(Li0.1, Al0.2)0.033, ceramic exhibits a colossal dielectric constant (CDC) with good frequency stability, which have a dielectric constant of ~10000 at the frequency of 1 kHz. Impedance spectroscopy shows that the CDC phenomenon is not associated with the internal barrier capacitance (IBLC) effect. M''(f) spectrum obtained from electric modulus (M^*=M^'-jM'') analysis reveals two relaxation processes P1 and P2. Frequency dependent ac conductivity data can be well fitted by the Correlated Barrier Hopping (CBH) model, showing that the CDC would be originated from the thermally activated electron hopping between two neighboring acceptor-donor defect complex sites over their Columbic barrier. A simple model involving these acceptor-donor defect complex dipoles and the Cole-Davidson distribution of relaxation time [2,3] can explain the CDC phenomenon with good frequency stability.
Authors : Minji Ko*(1), Seo Yeon Shin(1), Soomin Ahn(1), Seungje Lee(1) and Young Rag Do(1)
Affiliations : (1) Department of Chemistry, KOOKMIN UNIVERSITY, Seoul, Republic of Korea *lead presenter
Resume : For application to tri-packaged white down-converted light-emitting diodes (DC-LEDs), we used the hot injection method to synthesize bright and eco-friendly green Ag-In-S/Zn-In-S/ZnS (AIS/ZIS/ZnS) quantum dots (QDs). To obtain bright green AIS/ZIS/ZnS QDs, we proposed a ZIS inner-shell to reduce lattice mismatch between AIS core and ZnS outer shell. Two variables of shell precursors, low concentration and high concentration of zinc acetate dihydrate, were chosen to form the ZIS inner-shell. Unlike a low concentration of zinc acetate dihydrate, a high concentration of zinc acetate dihydrate using an exothermic reaction can lead to the formation of ZIS inner-shell and bright green AIS/ZIS/ZnS QDs. We also confirmed the formation of the ZIS inner-shell by Raman spectroscopy and X-ray diffractometry. The synthesized green AIS/ZIS/ZnS QDs showed a high photoluminescence quantum yield (PLQY) of 0.84 with a peak wavelength of 505 nm. For application to tri-packaged white DC-LEDs, we used red Cu-In-S/ZnS (CIS/ZnS) QDs synthesized using hot-injection method, the obtained green AIS/ZIS/ZnS QDs, and a blue InGaN LED. In addition, tri-packaged white DC-LEDs are realized at a correlated color temperature (CCT) in the range of 2700 K to 10000 K. The realized tri-packaged white DC-LEDs showed a high luminous efficacy (LE) value of 85 lm/W at applied current of 180 mA, color rendering index (CRI, Ra) of 93, and external quantum efficiency (EQE) of 0.30 at 5700 K.
Authors : K. KIRAN*, F. KADIRGAN**
Affiliations : * Nano Science and Nano Engineering Department, Istanbul Technical University ** Chemistry Department, ITU / Selektif Teknoloji Co. Inc. - Istanbul
Resume : The demand for the platinum group metals has increased over recent years due to the fact that around 60 percent of the world's annual output of platinum group (PGM) metals, particularly platinum (Pt), palladium (Pd) and rhodium (Rh), is utilized to manufacture automotive catalysts, known as catalytic converters as well. The automotive catalysts neutralise the toxic gases with the percentage above 90%. They catalyse the reduction of NOX, oxidation of HCs and CO to N2, CO2 and H2O. However, natural sources of PGMs are relative poor and thus it is important to develop efficient methods both economically and environmentally for recovering PGMs from secondary sources, suchlike catalysts used in the vehicles. PGM recovery methods are categorized into pyrometallurgical, hydrometallurgical, or biometallurgical, without regard to the source of PGM. The use of the correct metallurgical method largely depends on the sort of metal and the energy cost needed to process the waste. Here, a simplex and eco-friendly method was suggested in order to recover Pd from the spent catalyst on the basis of Al2O3 carrier. Respective catalyst used to be mounted and utilized orginally in a passenger car and it was coated by a thin film of Pd in the form of porous Al2O3 structure. To ensure the optimum recovery of Pd, a solution of distilled hydrochloric acid (HCl) and hydrogen peroxide (H2O2) were studied. Finally, addition of formic acid (HCOOH) was applied for separating Pd from the solution. The efficiency of the leaching was reported as 95% in response to the heat treatment at 80°C for 1.5 hours along with solid/liquid ratio of 1/9.5. Additional thermal process at 100°C for 1 hour was adequate to obtain efficiency of 95% for Pd recovery.
Authors : Daniel Salazar
Affiliations : BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940, Leioa, Spain
Resume : The renewed interest in permanent magnets based in the ThMn< sub>12< /sub>-type compounds is driven by their reduced content of critical elements and the current availability of advanced processing techniques scalable to the industry. As the nitride Nd(Fe,Mo)< sub>12< /sub>N< sub>x< /sub> compound show promising intrinsic properties, as high anisotropy field (>10T) and high saturation polarization (>1T), several processing routes to obtain high extrinsic ones were studied in this work. We investigate the fabrication and nitrogenation process of melt-spun NdFe< sub>10.5< /sub>Mo< sub>1.5< /sub> in order to obtain high coercivity powders for bonded and printed magnets. Nitride powders with Curie point of 370 ºC, a coercive field of 0.55 T and saturation polarization of 1 T were used as filler material in the manufacture of resins for bonded magnets and inks and filaments for screen- and 3D-printed magnets. Many efforts were made in the manufacture of anisotropic magnets.
Authors : Daniel Salazar
Affiliations : BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940, Leioa, Spain
Resume : Current advances on permanent magnets are strongly linked with the use of critical raw materials, as rare-earth elements (RE), whose main supplier does not apply eco-friendly policies to the mineral extraction process, avoiding the possibility to develop green technologies recommended by the EU and US governments. The scarcity of these raw materials, required for the development of commercial high-energy permanent magnets, boosts the search of new hard magnetic alloys with a reduced content of critical elements and similar performance to the current commercial magnets. The hard magnetic ThMn12-type phases are promising candidates due to its intrinsic properties; high saturation magnetization (>120 A·m2kg-1), Curie point (>300 ºC) and anisotropy field (>4 T), these properties were enhanced by the addition of light elements (H, N) at the interstitial sites of the 1:12 crystal structure or by Sm-substitution at the Th site. In addition, progress in the development of coercivity on samples with high anisotropy has been done using different processing methods. The intrinsic properties of the hard magnetic phases were significantly improved by the proposed methods. The maximum coercivity reached in these compounds is above 0.6 T and 1 T in nitride Nd-based and Sm-based 1:12 alloys, respectively. The successful experimental approaches used in this work demonstrate some ways to obtain high-performance permanent magnets with partial substitution of light REs and total substitution of heavy RE elements.
Authors : K. Balázsi1*, M. Furkó1, D. Aydogmus2, L. Yanmaz2, F.C. Sahin2, C. Balázsi1
Affiliations : 1Centre for Energy Research, Konkoly-Thege str. 29-33, 1121 Budapest, Hungary 2 Istanbul Technical University, Metallurgical and Materials Engineering Deptartment, Maslak, 34469, Istanbul, Turkey
Resume : The present work is focusing to aluminium oxynitride (AlON) that has a unique thermal and chemical stability which makes it the perfect candidate for a wide range of applications. Although there has been extensive research on this material, especially more recently because of increased commercial interest, extensive systematic powder synthesis and processing studies have been carried out to determine alternate, more cost efficient routes to fully dense transparent bodies. Samples alumina-ALN powder mixtures with nano-additions have been prepared and extensive EDS/SEM, XRD and TEM inestigations have been done. The four type of nano-additions with three different quantities were as follows: SiO2 0.35%, 0.45%, 0.55%, MgNO3 0.5%, 1%, 1.5%, CeO2 0.05%, 0.1%, 0.15%, CaCO3 0.3%, 0.4%, 0.5%. The results before attrition milling showed that in starting powder mixtures the distribution of AlN particles in the Al2O3 matrix is not homogeneous. The grain size of the Al2O3 was approximately 100-200 nm and 0.5-1 μm for the AlN. SiO2 was found only in the powder mixture with the highest (0.55%) SiO2 content. Mg was detected with N (where AlN particles could be seen). CeO2 was found only in the powder mixture with the highest (0.15%) CeO2 content. Ca was detected in the all powder mixtures and it occured with N. One hour-long attrition milling resulted in powder mixtures with homogeneous distribution. However, particles with fluor and zirconium content could be seen originating from the tephlon and ZrO2 milling spacers and agitators.
Authors : K. Balázsi1, M. Furkó1, Z. Liao2, J. Gluch2, D. Medved3, R. Sedlák3, J. Dusza3, E. Zschech2, C. Balázsi1
Affiliations : 1Centre for Energy Research, Konkoly-Thege str. 29-33, 1121 Budapest, Hungary 2Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Maria-Reiche-Str. 2, 01109 Dresden, Germany 3Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 040 01 Košice, Slovak Republic
Resume : The influence of the various content of the multilayered graphene (MLG) on the structural and mechanical properties of the final bulk porous silicon nitride-zirconia (Si3N4-ZrO2) based ceramics was investigated. The ceramic composites were prepared in the form of the laminated structure with different (5-30-5 wt% and 30-5-30 wt%) MLG content by hot isostatic pressing. ZrO2 particles were incorporated into the Si3N4 matrix by attrition milling to improve the mechanical properties of the final composite. Homogeneous distribution of the MLGs, a completed phase transition from α to β-Si3N4 in case of 5 wt% MLG have been observed. The structural examinations revealed that the multilayered graphene and zirconia particles owing to their different sizes and shapes influenced the porous microstructure evolution and the related mechanical properties of the composites. The sandwich structures enhanced the mechanical properties compared to reference ceramic with 30 wt% MLG. The position of the layer with higher graphene content, high ratio of alfa/ beta phase of Si3N4 and higher porosity had crucial effect on the final mechanical properties.
Authors : Liviu Leontie1, Veaceslav Sprincean2, Igor Evtodiev2,3, Liliana Dmitroglo2, Iuliana Caraman3, Mihaela Girtan4, Aurelian Carlescu5
Affiliations : 1 Faculty of Physics, Alexandru Ioan Cuza University of Iasi, Bulevardul Carol I, Nr. 11, RO-700506 Iasi, Romania; 2 Laboratory of Scientiﬁc Research „Photonics and Physical Metrology”, Faculty of Physics and Engineering, Moldova State University, A. Mateevici, 60, MD-2009, Chisinau, Republic of Moldova; 3 Ghitu Institute of Electronic Engineering and Nanotechnologies, Academy of Sciences of Moldova, Academiei, 3/3, MD-2028, Chisinau, Republic of Moldova; 4 Photonics Laboratory, (LPhiA) E.A. 4464, SFR Matrix, Angers University, Faculty of Sciences, 2 Bd Lavoisier, 49000 Angers, France; 5 Integrated Center for Studies in Environmental Science for North-East Region, Alexandru Ioan Cuza University of Iasi, Iasi 7000506, Romania.
Resume : Indium selenide (InSe) is a typical representative of group III-VI layered materials, with a direct band gap of about 1.3 eV and indirect one of 1.26 eV at room temperature. By splitting bulk InSe single crystals perpendicularly to the C6 axis, plan-parallel lamellae with atomically flat surfaces and thickness down to nanometer range can be obtained. InSe lamellae are comprised of elementary Se-In-In-Se packings bound by van der Waals forces, with closed valence bonds at surface. Due to mentioned characteristics, together with nature of optical transitions in the center of Brillouin zone and low surface-state density, InSe is considered among the first 5 most promising materials for photovoltaic, water splitting and transistor technology applications. In this work, through absorption, photogeneration, photoluminescence, EDX and Raman studies, influence of thermal preparation regime of ITO/InSe heterojunctions, as well as of Cd and Sn dopant concentration on the energy band diagram in the oxide/semiconductor interface layer is investigated. At the same time, relationships between the features of photosensitivity spectrum and the characteristics of localized states in the semiconductor layer of the oxide-semiconductor interface are established.
Authors : Nikolay Nedyalkov1, Reni Iordanova2, Lyubomir Aleksandrov2, Margarita Milanova2
Affiliations : 1Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shousse 72, Sofia 1784, Bulgaria 2Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, blvd. Akad. G. Bonchev bl.11, Sofia 1756, Bulgaria
Resume : Tungstate-lanthanum-borate glasses containing different amount of Nb2O5 were obtained by melt quenching technique. The glass compositions (50-x)WO3-25B2O3-25La2O3-xNb2O5, x= 5, 10 and 20 (mol%) were doped with 3 mol% Eu2O3 at the expense of La2O3 in order to examine their luminescence properties. The thermal parameters of the synthesized glasses were evaluated by differential thermal analysis. It was determined that the glass transition temperature increases with the increase of Nb2O5 but the crystallization temperature decreases. The short-range order of the synthesized glasses was determined by IR, Raman and UV-VIS spectroscopies. It was found that the amorphous network is built up with participation of WO6 and WO4, NbO6, BO3 and BO4 units. Photoluminescence emissions due to the 4f transitions 5D0→7Fj (j=0-4) of Eu3+ ions were observed. Influence of Nb2O5 content on the emission intensity of the prepared glasses was established. It was found that the glass containing 15 (mol%) Nb2O5 possesses the most intensive luminescence of Eu3+ ions. The charge transfer at room temperature from tungsten to europium ions was proved while such a transfer from niobium to europium was not observed. Acknowledgments: This work is supported by Bulgarian National Science Fund under project КП-06-Н29/7
Authors : Stefania Porcu (firstname.lastname@example.org)(a); Spencer Golze (b); Robert A. Hughes b; Svetlana Neretina (b), Pier Carlo Ricci (a)
Affiliations : a) Department. of Physics, University of Cagliari b) College of Engineering, University of Notre Dame (USA)
Resume : Nowadays, research in new materials is instrumental to reach a sustainable, energy saving and eco-friendly development. Materials free of “Critical” Raw elements are very attractive and the research in this direction is strongly increased, looking for available alternatives and the most promising materials are new organic materials. Polymers can guarantee very high versatility in terms of structural and optical response with high potential in several applications. We studied the properties of a novel organic compound (2,4-diamino-6-phenyl-1,3,5-triazine), thermally treated (400°), for the synthesis of gold nanopores controlling the degree of screw dislocation. Thanks to their properties the obtained structures are suitable for biosensing and imaging applications.
Authors : G. Petre(1,4), A. Stanculescu(1), M. Girtan(2), M. Socol(1), C. Breazu(1), L. Vacareanu(3), N. Preda(1), O. Rasoga(1), F. Stanculescu(4)
Affiliations : 1. National Institute of Materials Physics, 405A Atomistilor Street, P.O. Box MG-7, Magurele, 077125, Romania, email@example.com; 2. Laboratoire LPHIA, Université d’Angers, LUNAM, 2 Bd. Lavoisier 49045, Angers, France; 3. P. Poni Institute of Macromolecular Chemistry, 41 A Gr. Ghica Voda Alley, 700487, Iasi, Romania; 4. University of Bucharest, Faculty of Physics, 405 Atomistilor Street, P.O.Box MG-11, Magurele, 077125 Romania;
Resume : The most widely used transparent conductor electrode (TCE) in organic devices is Indium Tin Oxide (ITO) due to its high optical transparency, metallic conductivity and high work function favoring an efficient injection of holes into many organic semiconductors. Because indium is a critical raw material, expensive, short supply, toxic and difficult to use on flexible substrates, it is necessary to identify new alternative for TCE from cheaper materials showing high transmission and low resistivity for small thickness of the electrodes. This paper presents some investigations on the optical and electrical properties of the heterostructures realized with arylenevinylene oligomer: perylene diimide mixed active layer and 3 layers, oxide/metal/oxide TCE (e.g. ZnO/Ag/ZnO; ZnO/Au/ZnO, AZO/Ag/AZO, AZO/Au/AZO). The 3 layers electrode was deposited by sputtering on glass and optically and electrically characterized in correlation with the morphological and structural particularities evidenced by SEM, AFM and XRD measurements. The heterostructures were characterized by spectroscopic (UV-VIS, Photoluminescence) and microscopic (SEM, AFM) methods and the properties of heterostructures with different types of 3 layers TCE will be compared with those of the same heterostructures realized with ITO electrode. The effect of a supplementary layer of PEDOT-PSS intercalated between the TCE and organic layer on the properties of the heterostructures has been also investigated.
Authors : Jin-Seung Jung
Affiliations : Gangneung-Wonju National University
Resume : Environmental problems such as air pollution, soil contamination, especially refractory wastewater produced by some noxious organics, have aroused much attention in the area of environmental remediation. Recently, with a growing demand for clean and comfortable environment, purification technologies with high efficiency and low cost to reduce the pollutant contents of wastewater are urgently needed. TiO2 and ZnO are considered to be one of the suitable materials for photocatalyst due to its nontoxicity, biological inertness, chemical stability and low cost. Despite their obvious advantages, TiO2 and ZnO are a white powder difficult to handle and separate from a liqui solution, hence this problem is eliminated or minimized by various smart solutions. In this study, a facile and efficient approach for the fabrication of Ag coated Fe3O4@ZnO nanoparticles with a good core-shell structure is demonstrated. The magnetic cores of Fe3O4 act as the center for the growth of ZnO nanorods. As a result, the zinc oxide nanorods grown around Fe3O4 magnetic cores form a rod-like hybrid structure. The Fe3O4@ZnO-Ag core-shell microsphere possesses a relatively large specific surface area induced by noble metal nanoparticles, a magnetic behavior for easy reuse, and enhanced photocatalytic efficiency caused by metal-semiconductor chare transfer or energy transfer. As characterized by FE-SEM, HR-TEM and XRD, the as-synthesized Ag coated Fe3O4@ZnO nanoparticles exhibit a narrow size distribution. The Ag coated Fe3O4@ZnO photocatalyst exhibited high photocatalytic activity in the degradation of rhodamine B and methylene blue under solar light and visible light. The photodynamic process of Ag coated Fe3O4@ZnO rapidly generates reactive oxygen species (ROS). Therefore, the detection methods and generation mechanisms of the intrinsic reactive oxygen species (ROS) such as hydrogen peroxide (H2O2), singlet oxygen (1O2) and hydroxyl radical (′OH) in photocatalysis were comprehensively examined. Reactive oxygen species (ROS) confirmed once more under the presence of scavengers. The renewable photocatalytic activity of the photocatalyst was also examined.
Authors : P. Prepelita 1a , D. Craciun 1, I. Stavarache 2, F. Garoi 1, B. Sbarcea 3, V. Craciun 1
Affiliations : 1 National Institute for Laser, Plasma and Radiation Physics, PO Box MG-36, Magurele 077125, Ilfov, Romania 2 National Institute of Materials Physics, PO Box MG-7, Magurele 077125, Ilfov, Romania 3 ICPE-CA, Splaiul Unirii 313, Sector 3, 74204, Bucharest, Romania
Resume : This study reports the influence of the deposition conditions of SiO2 and ZnO oxide thin films on their structural properties. These films were deposited by rf-MS technique on quartz substrates. The film thickness values of 0.100-0.250 μm were measured using an interferometric method. The orientation of crystallites, surface morphology, mass density, structure and composition were investigated by XRD, XRR, XPS and SEM. The maxima and minima of transmission and reflection spectra recorded in the range 200-2500 nm for the analyzed samples are due to multiple reflections on the surfaces of the film, indicating that the studied oxide films were uniform. The values of the energy band gap were calculated from the absorption spectra, for ZnO and SiO2 samples, deposited onto quartz substrates. By calculating the average value of the refractive index in the investigated wavelength range it was found that, in general, the refractive index of the layer increased with its thickness. As a result, depending on the deposition conditions, the ZnO and SiO2 oxide films showed a good structural quality and adhesion to the substrate.
Authors : G. Faggio* (1), N. Lisi (2), R. Chierchia (2), R. Grillo (1), A. Foti (1), A. Armano (3), A. Sciortino (3), F. Messina (3), S. Agnello (3), G. Messina (1)
Affiliations : (1) DIIES Dept., University “Mediterranea”, Via Graziella, Loc. Feo di Vito, 89122, Reggio Calabria, Italy (2) ENEA, DTE PCU IPSE, Casaccia Research Centre, Via Anguillarese 301, Rome, Italy (3) University of Palermo, Dept. of Physics and Chemistry, Via Archirafi, 36, 90123, Palermo, Italy
Resume : Graphene (Gr), a two-dimensional material composed of carbon atoms arranged in a honeycomb lattice, is considered an excellent candidate for fabricating transparent conductive film for optoelectronic applications . High optical transparency , high electrical conductivity  chemical stability are the properties that identify graphene as a valid substitute for the indium tin oxide (ITO). Carbon dots (CDs) are a wide family of zero-dimensional (0D) carbonaceous nanoparticles with a diameter smaller than 10 nm capable of bright and tunable fluorescence . Their attractive optical properties  combined with low cost, low toxicity, water-solubility, photo-stability and biocompatibility have attracted attentions in view of many applications such as optoelectronics , photocatalysis  and solar energy harvesting . CDs-Gr composites, joining the main properties of CDs, such as optical activity, and Gr, such as high conductivity and transparency, can pave the way to new all-carbon optoelectronic devices. For these applications, the CDs-Gr composites have to be deposited in the form of 2D solid systems, and their interface and surface properties have to be carefully evaluated in order to tailor their optoelectronic behavior . In this work, the structural and optical properties of CDs deposited on Gr/SiO2/Si substrate are thoroughly investigated. In particular, a systematic micro-photoluminescence analysis, employing different excitation lasers from green to blue, shows that CDs maintain their emission tunability, but there is a reduction in the emission efficiency of the CDs in presence of Gr. The different electrical properties of Gr and SiO2, conductive the first and insulating the second, suggest the possibility of a photo-induced electron transfer between CDs and Gr.  F. Bonaccorso et al., Nature Photonics, 2010, 4, 611  R.R. Nair et al., Science, 2008, 320, 1308  X. Du et al., Nat. Nanotechnology, 2008, 3, 491  Ya-Ping sun et al., J. Am. Chem. Soc., 2006, 128, 7756  A. Sciortino et al., Phys. Chem. Chem., Phys. 2017, 19, 22670  L. Xiaoming et al., Adv. Funct. Mater., 2015, 25, 4929  X. Zeng et al., Appl. Catal. B Environ., 2017, 202, 33.  P. Mirtchev et al., J. Mater. Chem., 2012, 22, 1265.  G. Faggio et al., Phys. Status Solidi A, 2019, 1800559
Authors : Petr Hruska (1,2), Michal Novotny (1), Joris More-Chevalier (1), Ladislav Fekete (1), Jiri Bulir (1), Jakub Cizek (2), Oksana Melikhova (2), Jan Lancok (1)
Affiliations : (1) Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 182 21 Prague, Czech Republic (2) Charles University, Faculty of Mathematics and Physics, V Holesovickach 2, 180 00 Prague, Czech Republic
Resume : Aluminum films prepared by DC pulsed magnetron sputtering in a mixed atmosphere of argon and nitrogen exhibit two different types of morphologies depending on the N2/Ar ratio. Reflective Al is characteristic by a compact bulk-like structure and surface roughness linearly increasing with film thickness. Incident light (wavelength range from 190 nm to 1200 nm) is scattered into multiple directions however the total diffusion reflectance falls into range of 65 – 85% depending on the film thickness and wavelength of the incident light. Contrary to reflective Al, black Al films’ morphology resembles cauliflower/moth-eye structures. Such a surface is characteristic by a high light absorbance of 96 % and higher. Atomic force microscopy and transmission electron microscopy measurements showed a porous structure of black Al with pore sizes of ~10 nm and smaller. Positron lifetime spectroscopy measurements revealed an increased concentration of vacancy-like defects (mono-, di- vacancies, vacancy clusters) in black Al films compared to reflective Al films. In addition to vacancy-like defects black Al contains nano-cavities as observed by 3-gamma ortho-positronium annihilation. Applying the Tao-Eldrup model we estimated the mean size of nano-cavities to 5 A.
Authors : C.F. Ciobota1, R.M. Piticescu1, S. Bejan1, Yi Qin2
Affiliations : 1- National Institute for Non Ferrous and Rare Metals, Pantelimon, Ilfov, Romania 2- University of Strathclyde, Glasgow, UK
Resume : Nowadays there is an open challenge to obtain lead-free piezoelectric ceramics and trying to replace the PZT ceramics into energy harvesting applications. Perovskite materials have drawn great interest of researcher in this area. Nano lead-free piezoelectric BCZT Ba(Ti1-xZrx)O3-(Ba1-yCay)TiO3 (x=0.3;0.5 y=0.3;0.5) material was obtained through a hydrothermal process with controlled stoichiometry, this synthesis process will be scale-up in order to demonstrate operational reliability and recyclability. Nanostructured perovskite material denoted as BCZT was synthetized in one step process by hydrothermal method starting from soluble salts. KOH was used as mineralizer. The amounts of Ba(OH)*8H2O, Ca(NO3)2 · 4H2O, TiCl4 and ZrCl4 were weighed in agreement with the theoretical molar formula Ba(Ti1-xZrx)O3-(Ba1-yCay)TiO3 (x=0.3;0.5 y=0.3;0.5). The suspension was transferred to a Teflon vessel of an autoclave (5l, Berghof, Germany) with cooling system, for hydrothermal treatment at 40 at. and 473 K, for 2 h. Pressure was created inside the reaction system using argon gas. After the hydrothermal synthesis, the wet precipitate was subjected to spray drier in order to obtain spherical grain. Chemical composition was determined by inductively coupled plasma atomic emission spectroscopy (ICP-OES) technique. The microstructure of the powders was examined by using XRD analysis, morphology of the sample was investigated by SEM. The thermal behavior of the processed samples under non isothermal regime was investigated by simultaneous differential scanning calorimetry (DSC) and thermogravimetry (TG). Acknowledgement: FAST and Nano-Enabled SMART Materials, Structures and Systems for Energy Harvesting (FAST-SMART); EU H2020 Grant 862289.
Authors : David Payno (a), Manuel Salado (a), Michael Andresini (a), D. Gutiérrez-Moreno (c) Fulvio Ciriaco (d), Samrana Kazim (a,b) Á. Sastre-Santos (c), F. Fernández-Lázaro (c), Shahzada Ahmad (a,b)
Affiliations : (a) BCMaterials -Basque Center for Materials, Applications and Nanostructures (b) IKERBASQUE, Basque Foundation for Science (c) Área de Química Orgánica, Instituto de Bioingeniería, Universidad Miguel Hernández (d) Department of Chemistry, University of Bari “A. Moro”
Resume : The photovoltaic technology based on perovskite as absorber has received a lot of attention due to its potential for being a low-cost effective and high-efficiency technology to produce energy at large scale. In order to favour the charge extraction, hole-transport materials (HTMs) prepared on an n-i-p architecture has to be electronically and physically compatible with the perovskite film, while maintaining a low cost. The family of perylene diimides (PDIs) has received significant attention as dyes and charge selective semiconductors in electro-optical devices, due to its tuneable electronic properties and high stability. To explore new HTMs based on PDIs, we have selected and prepared 1.6 and 1.7 isomers of dipiperidin-N-yl PDIs which suggest good compatibility with perovskite after DFT simulations. As a proof of concept, we fabricate solar cell devices applying a very thin film of the PDIs as HTM. Unlike the reference device using Spiro-OMeTAD, we noted that PDIs does not require doping of external materials to have a good performance. This, along with an improved long-term device stability, demonstrate a good potential of PDIs to be used as HTMs, open the possibility of further investigation and optimization for its use in solar cells.
Authors : D. Metlina*, M. Metlin*, S. Ambrozevich*, D. Aminev*, D. Goriachiy*, I. Taidakov*, R. Avetisov**, R. Saifutyarov**, I. Avetissov**
Affiliations : *P. N. Lebedev Physical Institute of RAS **D. Mendeleev University of Chemical Technology of Russia
Resume : The design of highly emissive lanthanide-based compounds especially in NIR-region (800-1600 nm) is still a challenge, justifying the intense research activity of the scientific community in this field. А series of novel intensive NIR-emitting neodymium(III) complexes with pyrazolic 1,3-diketones bearing linear CnF2n 1 group (where n = 1,3,6) were synthesized. The symmetry of ligand environment was established by analysis of Stark splitting of emission lines in photoluminescence spectra and single crystal X-ray diffraction data, and was additionally investigated in terms of Judd–Ofelt theory. The most intensive luminescence of the complexes was observed for the (4)F(3/2) → (4)I(11/2) transition commonly used for lasing. However, the (4)F(3/2) → (4)I(9/2) transition unexpectedly makes the major integral contribution to the luminescence of the compounds. Based on the electroluminescence studies, we revealed the potential of complexes for fabrication of NIR-emitting OLEDs. Pure NIR-emission at 880 and in some cases around 1060 nm was observed for simple solution-processed OLED structures. New complexes due to their high solubility (up to 6 % by weight) in acrylic monomers such MMA were successfully used for preparation of hybrid materials optically transparent under visible light but emitting characteristic for Nd3 ion lines in NIR-region when exposed to mild UV-light (365 nm). We are grateful to Russian Science Foundation (project № 19-13-00272) for the financial support of this research.
Authors : Laura Lancellotti(1), Eugenia Bobeico(1), Paola Delli Veneri,(1) Rosa Chierchia(2), Nicola Lisi(2)
Affiliations : (1)ENEA - Portici Research Center, Piazzale E. Fermi, 80055 Portici (Na (2)ENEA - Casaccia Research Center, Via Anguillarese 301, Roma, 00123, Italy
Resume : In recent years, graphene has attracted great interest in different research fields while its electronic and optical properties have been intensively studied in view of several applications, in particular as transparent conductive electrode (TCE). Handling these 2D, atomic thickness films has proved an arduous task requiring the development of novel technologies. In this framework, it is extremely useful to be capable to fabricate and handle membranes composed of single or multi-layer graphene completed with metallic contacts of arbitrary geometry. This gives the possibility to transfer in a single step the contacted graphene on the target substrate using the cyclododecane supported technique invented by the authors. The main advantage of the technique is the possibility to obtain a novel TCE/metal-grid integrated structure, especially applicable in the photovoltaic field, which allows to avoid any further substrate process after the transfer of graphene. To test this concept, in the present work we have realized Graphene/Gold-grid membranes and transferred them on c-Si substrates in order to obtain Schottky barrier solar cells. The cell efficiency at 1 Sun illumination for a device with 4cm2 active area is 7.1%. The experiment can be extended to graphene membranes with grids made of other metals, such as Aluminium.
Authors : Abedin Nematpour, Mahmoud Nikoufard
Affiliations : ENEA, Energy Technology Department, Casaccia Research Center, Via Anguillarese 301, I-00123 Rome, Italy; Faculty of Electrical and Computer Engineering, Department of Electronics, University of Kashan, Kashan 87317-51167, Iran
Resume : Graphene-based Schottky-junctions offer a new interesting platform for photovoltaic devices, and Schottky-junction solar cells are intensively investigated with the aim to improve their performance. Recently, Schottky junction solar cells were fabricated by using a single layer of graphene as a metal. In this work, we propose a graphene/InP thin-film Schottky-junction solar cells by using a plasmonic structure. The graphene/InP thin film solar cell was designed with a periodic array of plasmonic back-reflector and Indium tin oxide (ITO) as an anti-reflection coating layer on top of the solar cell. 3D-simulations were carried out based on a finite difference method (FDM) method to determine absorption, the weighted absorption and the short-circuit current. The optimized design of the solar-cell structure, reached a maximum short-circuit current density and optical absorption of 33.01 mA/cm2 and 0.985 (98.5%), respectively under AM1.5G solar irradiation. The optimized design demonstrates a considerable reduction in absorbing layer thickness respect to the planar InP-based solar cell.
Authors : G. Contento, M. Massaro, L. Mirenghi, C. Ferrara, D. Valerini, F. Di Benedetto, M. L. Grilli, A. Rizzo
Affiliations : ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development
Resume : Al-doped ZnO is one of the most considered transparent conductive oxides (TCOs) as an alternative to the most commonly used Indium Tin Oxide (ITO), whose replacement is desirable to reduce the use of the critical indium element. In this work, Al-doped ZnO thin films were deposited using a RF magnetron sputtering system in Ar atmosphere by two distinct targets (ZnO and Al), where the Al percentage was varied changing the power ratio between the two targets from 0.1 to 0.7. Plasma emission spectroscopy during the deposition process showed the presence of Zn+, Zn, Al and O emission lines. The Zn and Al concentrations in the plasma can be calculated and correlated to the Al:ZnO thin films properties. Process optimization and technical improvements of the equipment were adopted to gain repeatability, accuracy and a better control of the systematic errors. X-ray diffraction (XRD) measurements were conducted to identify the microstructural modifications when varying the Al content in the films. X-ray photoelectron spectroscopy (XPS) analyses on the AZO films gave the binding energies of Zn 2p3/2 and 2p1/2 that are centered at 1021.6 and 1044.7 eV, respectively. No energy shift in the Zn 2p states is observed. The O 1s peak is asymmetric and can be resolved into two components, P1 at 530.2 eV and P2 at 531.6 eV. Peak P1 can be attributed to O2- ions surrounded by Zn2+, indicating Zn–O bonds; Peak P2 can be associated with O2-ions in the oxygen-deficient regions within the matrix of ZnO. The electrical conductivity and Seebeck coefficient were measured in standard Van der Pauw configuration, and their values are comparable with the literature.
Authors : Chiara Olla (1), Nicoletta Rusta (2), Stefania Porcu (1), Pier Carlo Ricci (1), Carlo Maria Carbonaro (1)
Affiliations : (1) Department of Physics, University of Cagliari, sp 8, km 0.700, 09042 Monserrato, Italy; (2) Department of Chemical and Geological Sciences and INSTM, University of Cagliari, sp 8, km 0.700, 09042 Monserrato, Italy
Resume : Critical raw materials (CRMs) are key elements for the operation of many lighting devices. In the last few years, research focuses on the study of luminescent nanomaterials free of CRMs. The discovery of new fluorescent carbon nanoparticles brought researchers to deepen their optical and electronic properties for these applications. In fact, Carbon dots (CDs) are carbon-based nanoparticles which exhibit tunable photoluminescence emission across the visible range. Starting from citrazinic acid and urea, we studied optical and structural properties of the green luminescent CDs obtained by hydrothermal synthesis.
Authors : Anusree V. K.1, P. Neenu Lekshmi1, Shwetha. G. Bhat2, Aditya A. Wagh2, Gangadhar Das3, P. N. Santhosh1
Affiliations : 1Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India 2Department of Physics, Indian Institute of Science, Bangalore, 560012, India 3Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560064, India
Resume : Multiferroics are materials possessing different ‘ferroic’ orders such as ferro-magnetism, ferro-electricity, ferro-elasticity etc. Many rare earth ortho-chromates and ferrites were reported to exhibit multiferroic properties and magneto-electric coupling. It was reported that in many of the rare earth chromates, the onset of polar ordering appears at temperatures slightly higher than their antiferromagnetic ordering. Here we investigate the temperature evolution of structural and dielectric properties of Holmium based ortho-chromate, HoCrO3. Polycrystalline HoCrO3 was prepared by conventional solid state synthesis route. Temperature variation of Synchrotron X-ray diffraction was done at Photon Factory Japan using a 300mm Debye-Scherrer diffractometer on the B12 beamline. Rietveld refinement of crystal structure at various temperatures was carried out using FullProf suit software. Magnetic measurement was done using SQUID-VSM (Quantum Design) and Dielectric spectroscopy measurements were carried using Broadband Dielectric/Impedance Spectrometer, Novocontrol technologies. Reitveld refinement of the synchrotron x-ray diffractogram at room temperature confirms the perovskite orthorhombic structure crystallizing in the Pbnm space group. Temperature evolution of synchrotron x-ray diffraction points to the presence of variation in unit cell volume around 240 K and 100 K. Magnetic measurement confirms the antiferromagnetic transition at 140 K. The compound exhibits a dielectric constant of 19.46 at 1.784 kHz at room temperature. Also, temperature variation of the real part of the dielectric constant reveals a typical relaxor like behavior with low temperature and high temperature plateaus along with two anomalies at 240 K and 140 K. Analysis of peaks in the loss tangent curves confirms thermally activated dielectric relaxation. The dielectric anomaly at 140 K indicates a possibility for magneto-electric coupling in the material. However, the peak at 240 K corroborates the volume change observed in synchrotron analysis which is associated with a possible structural transition (Pbnm to Pna21), usually observed in similar rare earth based ortho-chromates having ferroelectric ordering. In the present work synchrotron x-ray diffraction technique was used for the first time to confirm the structural transition in HoCrO3. Our structural as well dielectric studies proves HoCrO3 as a multiferroic material with magneto-electric coupling.
Authors : Jung Tae Lee, Changshin Jo, and Michael De-Volder
Affiliations : Department of Plant and Environmental New Resources, Kyung Hee University, Yongin, 17104, Gyeonggi-do, Republic of Korea; Department of Engineering, University of Cambridge, 17 Charles Babbage Road, CB3 0FS, Cambridge, UK; Department of Engineering, University of Cambridge, 17 Charles Babbage Road, CB3 0FS, Cambridge, UK
Resume : Because of high energy and power density, Li-Ion batteries (LIB) are the predominant energy storage technology to power mobile electronics and electric mobilities. The needs for higher energy is ever-increasing and one option to store sufficient amounts of energy is stacking multiple electrodes into one cell. The battery is constructed by battery electrodes consist of Cu foils coated with the anode material and Al foils coated with the cathode material, and separator soaked in electrolyte. While the Cu, Al, and separator are essential for the battery operation, they are inactive components that do not store energy. Increasing the thickness of the active material coating will decrease the relative fraction of this dead volume. Unfortunately, producing thick electrodes is challenging because of cracking and flaking during drying, and further, both the electron and Li-ion transport are poor through thick layers. In this presentation, we will discuss key performance differences between conventional electrodes and bi-continuous electrodes and offer our explanation to the improved areal capacity and rate performance.
Authors : Ruchi Bhardwaj, Kishor Kumar Johari, Bhasker Gahtori, Nagendra S. Chauhan, Sivaiah Bathula, S. R. Dhakate.
Affiliations : CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012, India; Academy of Scientific & Innovative Research (AcSIR), CSIR-NPL Campus, New Delhi 110012, India; Department of Micro & Nanofabrication, International Iberian Nanotechnology Laboratory (INL), Braga 4715-330, Portugal; School of Minerals, Metallurgical and Materials Engineering, IIT Bhubaneswar, 752050, India.
Resume : Thermoelectric (TE) materials are prospective candidates for the energy applications by converting the waste heat into electricity. CoSb3 is a simple binary compound which can be used as a potential TE material for a wide range of temperature. Pristine CoSb3 has n-type character at room temperature, which changes to p-type at ~450K. Some of the research groups have observed p-type [1, 2] while some obtained n-type [3-5] conduction in CoSb3 by similar processing routes. This kind of bipolar nature of the CoSb3 could be useful to tune it as a p-type or n-type TE material. There are some studies which show that the excess of Sb in CoSb3, i.e. CoSb3+x eliminates the bipolar conduction in CoSb3 and leads to p-type conduction . This work presents the effect of stoichiometric ratio on the thermoelectric performance of the CoSb3 based Skutterudites materials. We have synthesized a series of CoSb3 based samples with different stoichiometry by changing the Sb and Co ratio and studied the effect on the TE properties of the alloy. The fast and cost-effective route of arc melting and spark plasma sintering was utilized for the sample preparations. The temperature-dependent electrical and thermal transport properties were measured and the figure-of-merit (ZT) has been calculated. The experimental results indicate that all of the synthesized samples exhibit a semiconducting behavior and yield a high Seebeck Coefficient (n-type conduction) from room temperature to ~550 K. Thereafter, it shows the p-type conduction. Further, an enhanced figure-of-merit (ZT) ~ 0.06 at 430 K was realized for the particular composition Co0.97Sb3.03. The TE performance of these alloys can be improved by employing the doping approach. References  T.H. Nakagawa H, Kasama A, Anno H and Matsubara K, Proc. 16th Int. Conf. on Thermoelectrics (Dresden, Germany) (Piscataway: IEEE) (1997) 351.  Z. Zhou, C. Uher, A. Jewell, T. Caillat, Influence of point-defect scattering on the lattice thermal conductivity of solid solution Co (Sb 1− x As x) 3, Physical Review B, 71 (2005) 235209.  Y. Kawaharada, K. Kurosaki, M. Uno, S. Yamanaka, Thermoelectric properties of CoSb 3, Journal of alloys and compounds, 315 (2001) 193-197.  K. Wojciechowski, J. Toboła, J. Leszczyński, Thermoelectric properties and electronic structure of CoSb3 doped with Se and Te, Journal of alloys and compounds, 361 (2003) 19-27.  V. Kuznetsov, L. Kuznetsova, D. Rowe, Effect of partial void filling on the transport properties of NdxCo4Sb12 skutterudites, Journal of Physics: Condensed Matter, 15 (2003) 5035.  W.-S. Liu, B.-P. Zhang, J.-F. Li, L.-D. Zhao, Effects of Sb compensation on microstructure, thermoelectric properties and point defect of CoSb3 compound, Journal of Physics D: Applied Physics, 40 (2007) 6784.
Authors : Jiri Bulir, Joris More Chevalier, Ladislav Fekete, Katerina Horakova, Sergii Chertopalov, Lenka Volfova, Michal Novotny, Jan Lancok
Affiliations : Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, 18221 Prague 8
Resume : Transition metal nitrides possess high thermal stability, high hardness, good tribological properties. Among them, some nitrides, such as zirconium nitride, excel in their optical and electrical properties, making them a suitable material for plasmonic applications. In this work, we deal with a study of the growth process of zirconium nitride (ZrNx) films by means of RF magnetron sputtering of Ti target in a reactive nitrogen ambient. The resulting structure and corresponding plasmonic properties of ZrNx coatings are very sensitive to some deposition parameters, especially, the composition of Ar/N2 gas mixture. Different chemical compositions, such as ZrN, Zr2N, Zr3N4, and ZrN2, can be obtained via the control of the sputtering reactive gas mixture that leads to different physical properties of the resulting zirconium nitride film. The films are grown on fused silica, silicon and MgO substrates at a substrate temperature ranging from 20°C to 500°C. The growth process is monitored using an in-situ spectral ellipsometer in a spectral range from 245 to 1690 nm. The ellipsometric data are analyzed using mathematical models based on Drude-Lorentz oscillators. A number of physical parameters, such as free-electron concentration, Drude relaxation time and electrical resistivity, are estimated at each stage of the deposition process by proper analysis of dielectric functions. Special attention is paid to the initial stage of growth when the free-electron behavior is significantly influenced by the interface between the substrate and the ZrNx film. The obtained results are compared and discussed with those obtained by Van der Pauw and Hall effect measurement. The crystallinity and surface morphology were analyzed by X-ray Diffraction method (XRD) and Atomic Force Microscopy (AFM).
Authors : A. DJEBAILI 1*; Ilhem. R. KRIBA 1; Z. SKANDERI 2; A. LAKHZOUM 3
Affiliations : 1 Laboratory of chemistry and environmental chemistry - University of Batna 1- Algeria 2 Institute of Hygiene and Industrial Safety- University of Batna 2- Algeria 3 Faculty of Biology - University of Batna 2- Algeria
Resume : Our work has allowed us to clarify the relations structures / properties and the isomerization reactions of icosadeca-ene. As regards the relations structures / properties, our results are: 1- The study of the conduction properties of icosadeca-ene doped with iodine gas at saturation as a function of various parameters regulating morphology and density of the material was optimized. In particular we have shown that the two key parameters governing the electrical conductivity of the polymer are the density and the fibrillar structure of icosadeca-ene. 2- The comparison of samples prepared horizontally and vertically gave a conductivity of greater than ~ 45 % for those deposited vertically, thereby reflecting the difference in morphology of the two types of film.. 3- The study of the ohmic conductivity of undoped and thermally isomerized samples showed a very different behavior depending on whether the icosadeca-ene film is deposited horizontally or vertically, thus confirming the different morphologies of the analyzed films. With regard to isomerization reactions of icosadeca-ene, our results are: i- The study of the thermal isomerization Cis / Trans of undoped icosadeca-ene by differential thermal analysis allowed us to calculate the activation energy of the reaction Ea=30.57 kcal/M, as well as the pre-exponential factor A = 3.7*1014 /s regardless of the type of polymer considered (deposited vertically or horizontally). ii- The kinetic studies by DSC showed that the isomerization reaction was neither of order 1, nor of a simple order. iii- An additional study of the thermal isomerization was carried out by Raman backscattering . This study allowed us in particular to establish a new original method for the determination of the isomeric composition of samples of icosadeca-ene. Also a relation for connecting the laser power to the induced temperature at the impact level was proposed. Finally, the kinetics of isomerization approaches the order 2/3. Note that the activation energy and the pre-exponential factor of the isomerization reaction determined by this method are different from those obtained by DSC.
Authors : K. BENOUMSAAD1*; ILHEM. R. KRIBA2; A. DJEBAILI2; A. LAKHZOUM3
Affiliations : 1 Faculty of Sciences – Department of hydraulic- University of Batna 2- Algeria 2 Laboratory of chemistry and environmental chemistry - University of Batna 1- Algeria 3 Faculty of Biology - University of Batna 2- Algeria
Resume : The aim of this work was on the one hand the development of theoretical models ( mathematical) to numerically simulate the experimental results of variations in the electrical conductivity as a function of various parameters, and on the other hand, the study of boundary conditions necessary for the numerical resolution of the heat propagation equation. Note that all obtained theoretical models are of the linear or sigmoidal form, Boltzmann type. Most obtained models allowed finding relationships more or less simple between the different parameters with an acceptable relative error of calculation, which allowed us to calculate theoretical values very close to the experimental values for the physical variables studied. Some of our models have given incorrect values , this can be explained by the fact that our calculation method is not reliable for this kind of data (values in small intervals). Note that this type of calculation can be improved by using other interpolation methods in particular the method of cubic splines. The model we have developed for solving the heat propagation equation, can serve in the research on the estimation of the isomerization temperature of tetradecahepta-ene by laser effect, which is widely used in current studies on the polyacetylene. Finally, it should be noted that our model for solving the heat propagation equation can be more efficient when the semi-empirical method is used to set the condition at the lower boundary of the domain.
Authors : Xiaoyan Wang, Kui Yi, Guohang Hu
Affiliations : Laboratory of Thin Film Optics, Shanghai Institute of Optics and Fine Mechanics, Shanghai 201800, China
Resume : In order to interpret the dynamic variation of thin film material during high power laser irradiation, the variation of optical constants and thickness of single layer coatings at different temperature was studied by combining the ellipsometry and the heating stage. From room temperature to 320°, the refractive index of SiO2, HfO2 and Al2O3 single layer decreases first and then increases, the thickness of these layers increases first and then decreases. But their inflection point occurred at different temperature, and the amount of change was also different for the layer with different material. Thermal expansion and water evaporation processes were applied to explain the temperature dependent properties of the dielectric coatings. The thermal damage and thermal distortion under high energy laser irradiation was interpreted from the view of optical property variation of the material, this will probably lead to a better understanding of the physical principles behind the laser-matter interaction.
Authors : Z. Cherkezova-Zheleva, D. Paneva,
Affiliations : Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bldg. 11, 1113 Sofia, Bulgaria
Resume : Mechanochemical treatment of waste materials is a powerful tool for pollution remediation and waste management. Mechanochemistry is defined to describe the chemical and physicochemical transformations of materials as a result of the mechanical energy input. On the other hand mechanochemical activation is a possibility to obtain products in a metastable state which increase their chemical activity. Four Fe–based amorphous alloys containing critical raw materials (CRM) were treated in a high-energy planetary ball mill at different conditions. The exact chemical compositions of studied materials are: Fe81B13.5Si3.5C2, Fe78B15Mo2Si5, Fe67B14Co18Si, and Fe40B16Ni40Mo4. The aim of the study is to investigate the appropriate conditions of mechanochemical processing of these materials to obtain partial crystallisation and formation of nanocrystals in the amorphous ribbon structure. The as-prepared active materials have higher specific surface area, which is also of great importance for their reuse for dye-contaminated wastewaters remediation. Characterisation of the bulk and the surface of initial and MC treated samples was done using powder X-ray diffraction (XRD), RT and LNT Mössbauer spectroscopy (MS), as well as conversion electron MS. Acknowledgements: The authors gratefully acknowledge the financial support of the Bulgarian National Science Fund at the Ministry of Education and Science - Project № КП-06-КОСТ/18/ 2019.
Authors : D. Louloudakis*, K. Mouratis, J. Gil-Rostra, E. Koudoumas, A. R. Gonzalez-Elipe
Affiliations : Center of Materials Technology and Photonics, School of Engineering, Hellenic Mediterranean University, 71410 Heraklion, Crete, Greece; Center of Materials Technology and Photonics, School of Engineering, Hellenic Mediterranean University, 71410 Heraklion, Crete, Greece / Physics Department, University of Patras, 26500 Patras, Greece; Instituto de Ciencia de Materiales de Sevilla (CSIC-USE), Avenida Americo Vespucio 49, E-41092 Sevilla, Spain; Center of Materials Technology and Photonics, School of Engineering, Hellenic Mediterranean University, 71410 Heraklion, Crete, Greece / Department of Electrical and Computer Engineering, School of Engineering, Hellenic Mediterranean University, 71410 Heraklion, Crete, Greece; Instituto de Ciencia de Materiales de Sevilla (CSIC-USE), Avenida Americo Vespucio 49, E-41092 Sevilla, Spain
Resume : Last decades, scientific interest has been attracted for electrochromic coatings, since these are essential in a variety of novel technological applications such as switches, batteries and smart windows. Tungsten trioxide is one of the most common electrochromic film for smart window applications that can be used in order to reduce the energy consumption on buildings. To date many methods, such as sol-gel, hydrothermal synthesis, chemical vapour deposition (CVD) and magnetron sputtering, have been used for the deposition of WO3 layers. As has been shown, one very important parameter for the response of the layers is their morphology. In this work, amorphous WO3 coatings were grown on indium tin dioxide glass substrates using magnetron sputtering with tungsten target and various amount of vacuum in the deposition chamber. The coatings were characterized by X-ray diffraction, XPS, UV-Vis-IR spectroscopy, scanning electron microscopy and cyclic voltammetry in order to investigate the importance of their porosity in the improvement of their electrochromic performance, including durability, time response, charge density and coloration efficiency.
Authors : Maria Luisa Grilli
Affiliations : ENEA - Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Casaccia Research Centre, Via Anguillarese 301, 00123 Roma, Italy
Resume : There is a growing concern worldwide about securing access to metals and minerals needed for economic production. This study offers a survey of critical raw materials (CRMs) used in energy, optoelectronics, transportation and machinery manufacturing. Understanding of the role of CRMs and a careful evaluation of environmental and health impacts are key factors in materials’ substitution, when searching for alternatives able to maintain the performance of components and products. The CRMs issue is analysed considering main actors: Europe, Japan, United States and China.
Authors : Mehmet Yilmaz1,2,* and Maria Luisa Grilli3
Affiliations : 1Department of Science Teaching, K. K. Education Faculty, 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 3 ENEA-Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Energy Technology Department, Casaccia Research Centre, Via Anguillarese 301, 00123 Roma, Italy
Resume : After Indium was included in critical raw material coverage by the European Union, researchers have recently begun to show interest in the synthesis and characterization of In-free multi-functional materials. For these materials to be used in areas where indium is used, such as optoelectronic applications, it should show similar properties with indium . Therefore, structural and optical characterizations which are effect their usability in that kind of application are very important. In this context, it can be said that II-VI semiconducting materials such as MgO and CdO exhibit similar structural and optical properties compared with the Indium doped tin oxide. However, among these multifunctional semiconducting materials ZnO steps forward due to its unique properties such as wide bandgap, large exciton binding energy, high chemical stability, and usability in environment-friendly applications [2,3]. Also, these unique properties of ZnO can be altered by both growth technique and external doping . Among the rare earth metals, Nd is one of the elements commonly used in high power laser applications, as well as the reduction of the optical band spacing of ZnO as a result of the substitution of Nd3+ ions into the ZnO crystal structure, makes ZnO useful for applications like photocatalytic applications . Similarly, in this study neodymium-doped ZnO thin films were grown by simple chemical spray pyrolysis technique in the Nd range of 0 – 5 at.% to investigate its usability in optoelectronic applications. For this aim, XRD and UV-Vis-NIR spectroscopy measurements were conducted. According to XRD analysis, the Nd-doped ZnO films have been exhibited a smooth, dense, and wurtzite phase. Also, the results showed that with the variable Nd doping concentration, the films can be adjusted to have semiconductor properties with good optical transmittance in the visible range. All results and variations in structural and optical properties of ZnO films as a function of Nd doping have been correlated and discussed in detail. References  Aydogan, S., & Yilmaz, M. (2019). Crystallographic disorders depending on monovalent cations addition and their effects on ZnO's characteristics. Ceramics International.  Rani, T. D., Tamilarasan, K., Elangovan, E., Leela, S., Ramamurthi, K., Thangaraj, K., ... & Liebig, A. (2015). Structural and optical studies on Nd doped ZnO thin films. Superlattices and Microstructures, 77, 325-332.  Subramanian, M., Thakur, P., Gautam, S., Chae, K. H., Tanemura, M., Hihara, T., ... & Jayavel, R. (2009). Investigations on the structural, optical and electronic properties of Nd doped ZnO thin films. Journal of Physics D: Applied Physics, 42(10), 105410.  Yilmaz, M. (2019). A function of external doping: Characteristics of inorganic nanostructure based diode. Ceramics International, 45(1), 665-673.  Kumar, S., & Sahare, P. D. (2012). Nd-doped ZnO as a multifunctional nanomaterial. Journal of rare earths, 30(8), 761-768.
Authors : Rasoul Khayyam Nekouei (1)(2)(*), Ignacio Tudela (2), Farshid Pahlevani (1), Veena Sahajwalla (1) (*) Presenter and Corresponding Author
Affiliations : 1. Sustainable Materials Research and Technology (SMaRT) Centre, School of Materials Science and Engineering, University of New South Wales (UNSW), Sydney, 2052, Australia 2. School of Engineering, The University of Edinburgh, Edinburgh, EH9 3FB, United Kingdom
Resume : Global energy shortage and greenhouse gas emissions caused by fossil fuels mean that clean, sustainable, and renewable energy is necessary. Waste is another concern, with electronic waste gaining importance due to the growing global consumption of electronic devices that are difficult to recycle due to the complex and hazardous nature of electronic materials. The study here presented aimed at tackling both issues at the same time: the valorization of e-waste to produce a bi-functional nanomaterial for both energy storage and energy harvesting applications. The bi-functional nanomaterial, with an overall thickness around 150 nm, consists of a two-step electrodeposited three-layered copper oxide with different oxidation states (0, 1, and 2) to enhance efficiency which can act as (a) a supercapacitor material for energy storage, and (b) photo-electrocatalyst for solar water splitting. As prepared (i.e., before thermal treatment), the film behaves as a supercapacitor with a capacitance of 106 F.g-1. Low-temperature heat treatment can then transform the film into a photo-electrocatalyst delivering a photocurrent of up to 2.3 mA.cm-1, demonstrating that the functionality of the bi-functional nanofilms can be tuned by varying the ratio of oxidation states of Cu in the film through the heat treatment. EIS results revealed that the electron-hole activity of the film differed substantially in the presence of the light, although the copper oxide film can also experience low stability in certain conditions. Keywords: photocatalyst, water splitting, supercapacitor, renewable energy, sustainability, recycling of electronic waste, nano thin film, electrochemical synthesis
Authors : Kishor Kumar Johari1,2*, Ruchi Bhardwaj1, 2, Nagendra S. Chauhan3, Sivaiah Bathula4 and Bhasker Gahtori1, 2
Affiliations : 1 CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012, India, 2Academy of Scientific & Innovative Research (AcSIR), CSIR-NPL Campus, New Delhi 110012, India, 3 Department of Micro & Nanofabrication, International Iberian Nanotechnology Laboratory (INL), Braga 4715-330, Portugal, 4 School of Minerals, Metallurgical and Materials Engineering, Indian Institute of Technology (IIT) Bhubaneswar, Bhubaneswar 752050, India
Resume : Thermoelectric (TE) is the promising technology for waste heat recovery and the performance of TE devices is given by figure-of-merit, ZT=(S^2 ?T)??, where, S, ?, T & ? stands for Seebeck coefficient, electrical conductivity, absolute temperature & total thermal conductivity, respectively. The combined term S^2 ? describes the power factor (?) which represents the electronic part in TE performance. Half-Heusler (HH) alloys lead the promising class of materials for several applications such as thermoelectrics, magnetism, spintronic. Among HHs, ZrNiSn is widely studied for its thermoelectric properties. Bodak et al.1 show the low-temperature electronic transport and magnetic properties of Mn-doped ZrNiSn. Here, we have investigated the effect of Mn-doping on the electronic transport properties of ZrNiSn for high temperature (room temperature to ~873 K). The ZrNi1-xMnxSn (x=0-0.04) samples were prepared via Arc Melting and then consolidated by using Spark Plasma Sintering. The desired half-Heusler phase for all the synthesized samples was confirmed by the X-ray diffraction technique. Further, the samples were characterized for thermoelectric properties. The electrical conductivity increases with temperature which is corresponding to the semiconducting behavior. At high temperature ~873 K, electrical conductivity was realized to be decreased in Mn-doped ZrNiSn and Seebeck coefficient shows marginal variation compared to pristine ZrNiSn. The power factor of 3.53 mW-1K-2 at ~873 K was realized in pristine ZrNiSn HH which was found to be decreased in Mn-doped ZrNiSn HHs. Reference: 1. Bodak, O.; Padlyak, B.; Stadnyk, Y. V.; Pierre, J.; Tkachuk, A.; Romaka, L.; Gorelenko, Y. K., Synthesis, crystal structure and physical properties of ZrNiSn semiconductor doped with Mn. Journal of alloys and compounds 2001, 317, 357-362.
Authors : Nadhira Laidani (1)*, Ioana Luciu (1,2), K. M. Safeen (1,3), S. Mariazzi (4), L. Raveli (4) and R.S. Brusa (4).
Affiliations : (1) Fondazione Bruno Kessler, Centro Materiali e Microsistemi, Via Sommarive 18, 38123 Trento, Italy; (2) TRUMPF Hüttinger GmbH + Co. KG, Boetzinger Strasse 80, 79111 Freiburg, Germany; (3) Abdul Wali Khan University, Department of Physics, 23200 Mardan, Pakistan; (4) Università di Trento, Dipartimento di Fisica, Via Sommarive 15, 38123, Trento, Italy.
Resume : Non-ITO transparent and conductive oxide films are materials of growing importance in application fields like thin film solar cells, photocatalysis, environment purification, gas sensors or photo-electro-chromic devices and other emerging technologies. In this work, TiO2 and Nb-doped TiO2 thin films prepared by RF sputtering in different atmospheres (Ar, Ar-O2 and Ar-H2) were deposited. The electrical and optical properties of the Nb-doped TiO2 thin films, in the as-grown state and after vacuum annealing, were studied in relation with the chemical properties, structural defects and crystallinity of the films grown in the different sputtering gas mixtures. Strong correlations were evidenced between the nature, the morphology and the environment of the defects and the electrical parameters characterizing the doped films.
Authors : Moufida Mansouri1* Cristian Tunsu, Burcak Ebin, Lucy Ajakaiye Jensen, Martina Petranikova
Affiliations : Chalmers University of Technology, Department of Chemistry and Chemical Engineering, Nuclear Chemistry and Industrial Materials Recycling, Gothenburg, SE-412 96, Sweden
Resume : The Hydrometallurgical processing of nickel metal hydride (NiMH batteries) generates a feed containing several REEs. In the majority of the developed processes, REEs are recovered as a mixture. To increase their potential, the utilization of this mixture should be explored. Otherwise, the demand for individual separation of REEs will limit the feasibility of current technologies. Here, the reuse of the outputs generated by recycling for synthesis of new magnetocaloric materials has been investigated. The outputs utilized was a rare earth element-rich product. After removing some impurities from this feed, especially aluminium, we have used the obtained product in the manufacturing of advanced REEs-based magnetocaloric materials for magnetic refrigeration especially manganites. The X-ray diffraction analysis shows that the magnetocaloric samples are well crystallized with presence of secondary phases REE-oxide and Mn2O3. We have studied the magnetic and magnetocaloric effect properties of the obtained samples.
Authors : Bosco Rodriguez, Cristina Echevarria, Daniel Salazar, G.C. Hadjipanayis
Affiliations : BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940, Leioa, Spain; Department of Physics, University of Oviedo, Oviedo, Spain; BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940, Leioa, Spain; Dept. Physics & Astronomy, University of Delaware, Newark, DE 19716, USA
Resume : Currently, electric motors and generators use high energy permanent magnets based on RE2Fe14B phases (RE: rare earth) with high amounts of RE often including heavy-RE metals (Dy, Tb), the most critical group of the raw materials. REFe12 alloys are seen as potential alternatives to RE 2 Fe 14 B since they have a significantly lower amount of RE-metals with similar or better values of remnant magnetization (MR) and high magnetocrystalline anisotropy (MCA), which can give rise to a large energy product (BH) max. However, these 1:12 alloys need other elements (i.e. Ti, Si, Mo) replacing Fe in order to stabilize the ThMn 12 tetragonal structure that gives rise to the high values of MCA. In this work, we have studied the SmFe 12 system with small substitutions of Mo in order to stabilize the 1:12 tetragonal structure and determine its effect on the MCA and the resulting coercivity in nanostructured magnets. Alloys with nominal compositions SmFe 12-x Mo x (x = 0.5, 1) were produced by arc-melting and then annealed at 1050 ºC for 48 h (intrinsic properties of the 1:12 phase on field-oriented powders). Extrinsic properties were studied in melt spun ribbons: wheel speeds of 15 and 35 m/s (resulting into amorphous or highly disordered ribbons), which were heat-treated, in vacuum, at different temperatures ranging from 650 ºC to 950 ºC for different times in order to obtain nanostructured ribbons that crystallized in the ThMn12 tetragonal structure. Structural and magnetic characterization showed that small Mo substitutions (x = 0.5) can stabilize the uniaxial 1:12 structure keeping high MCA (anisotropy field H a >10 T), developing coercivities of 0.36T after optimal heat treatments. This coercive field is still low regarding to H a . This may be due to the crystallization of bcc-Fe phase during processing of samples as a consequence of the Sm evaporation.
Authors : Maria Luisa Grilli1, Anna Sytchkova1, Sylvia Boycheva2
Affiliations : 1) ENEA, Energy Technology Department, Casaccia Research Center, Via Anguillarese 301, 00123 Rome, Italy 2) Technical University of Sofia, Department of Thermal Engineering and Nuclear Power Engineering, Sofia, Bulgaria
Resume : Indium Tin Oxide (ITO) is a unique material with optical and electrical characteristics that make it the material of choice in many applications such as displays, touch screens, solar cells and optoelectronic devices. ITO main constituent (about 78 wt%) is In, a by-product of Zn metal, which is subjected to large price oscillations and has been listed recently among he critical raw materials (CRMs) for EU. In this work the report on the effect of growth parameters on the optical and electrical properties of highly transparent and conductive Al-doped zinc oxide (AZO) single layer films and AZO/Ag/AZO multilayers fabricated by radio frequency sputtering. The electrical and optical properties of the films were investigated as a function of the growth parameters (substrate temperature, radio frequency power, working pressure and oxygen partial pressure). High transmittance (up to 91%) and low sheet resistance (down to 33 Ohm/square) were measured for AZO films, while lower transmittance up to 83% and lower sheet resistance down to 15 Ohm/square for Ag/AZO multilayers. The goodness of the TCOs was evaluated basing on the optical and electrical properties by using the Haacke’s figure of merit.
Authors : Gabriele Tarquini1, Mariasole Di Carli2 e Pier Paolo Prosini2.
Affiliations : 1. Università degli Studi di Roma "La Sapienza", via Aldo Moro 5, Roma, Italy. 2. ENEA, C.R. Casaccia, via Anguillarese 301, 00123 - Roma
Resume : Stationary electrical storage applications needed to power utility grids and industrial sites require battery packs that have the ability to combine high power, high capacity, and long cycle life. In addition, battery systems for stationary application are expected to have optimal sustainability across the entire supply chain, including the replacement of essential raw materials. In fact, the materials needed for the construction of the current generation lithium-ion batteries, such as cobalt, nickel or manganese, may not be available enough to meet the demand for large-scale applications. The interest in next-generation Li-ion and non-Li-ion batteries is growing, and among these lithium-sulphur batteries represent a promising challenge due to the low cost and high availability of sulphur. However, the use of lithium metal places some limits related to the safety of the device. One possibility to decrease the risk associated with the use of lithium metal is to reduce or eliminate liquid electrolyte with the result of an increase in the safety of the devices. in this work we propose the use of gelled electrolytes for the realization of lithium-sulphur batteries with high capacity and safe use. The results obtained in the realization of a lithium-sulphur battery with a polymeric solid electrolyte based on PEO gelled with low weight polyether will be presented.
Authors : Antonio Rinaldi
Affiliations : ENEA, SSPT department, Via ANguillarese 301, Rome (IT)
Resume : The need for high performance materials for high temperature applications and severe harsh conditions is a major challenge in the roadmap towards a circular economy by the SETPLAN. The advances from the H2020 project NEXTOWER provide some inputs on the materials technologies and the design for maintenance strategies that could be deployed to produce components with longer service life in applications such as concentrated solar power (CSP) and CO2 - technology. Starting from results achieved on high temperature liquid lead environment of special layered metal systems, a general perspective is drawn for cross-cutting applications where partial substitution and better OPEX can be pursued.
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Critical Raw Materials and Recycling : Maria Letizia Ruello
Authors : Pier Luigi Franceschini, Roland Gauss
Affiliations : EIT RawMaterials
Resume : Our modern society relies heavily on electronic and optoelectronic devices to sustain communication networks and industrial systems. The devices and systems at the core of digital transformation and the energy transition are based on hardware requiring an intensive use of Critical Raw Materials (CRM) . In 2016, the EIT RawMaterials (EITRM) started its operations to address innovation and education, also with emphasis to CMRs. Initiated and funded by the EIT (European Institute of Innovation and Technology), a body of the European Union, the EITRM is the largest consortium in the raw materials sector worldwide. Its vision is to develop raw materials into a major strength for Europe. Its mission is to enable sustainable competitiveness of the European minerals, metals and materials sector along the value chain by driving innovation, education and entrepreneurship. Substitution of critical and toxic raw materials is one of the core thematic areas covered by the community: as of 2020, 25 active projects are covering the substitution of CRMs. In these projects partners collaborate on finding new, innovative solutions to secure the supplies and sustain the raw materials sector in Europe. The talk will briefly explain the opportunities available within the EITRM?s programmes, starting with an overview of the challenges posed by the transition to the use of renewable energies and to electric vehicles and what impact this will have on the demand of specific metals and minerals. An overview of the project portfolio that the EIT RawMaterials is deploying to tackle these challenges will be given. We will also show some specific examples of projects addressing substitution and recycling of CRMs.
Authors : Marianna Panou, Anastasia-Maria Moschovi, Ekaterini Polyzou, Iakovos Yakoumis
Affiliations : MONOLITHOS Catalysts & Recycling Ltd.
Resume : Platinum Group Metals (PGMs) are considered critical raw materials, thus their recycling and re-use is of outmost importance. Among the PGMs, Platinum (Pt), Palladium (Pd) and Rhodium (Rh) are the basic metals used in catalytic converters. Concerning EU standards for emission control, it is expected the demand for PGMs to be increased, meeting the need for zero emissions. It is a mandatory that, research is focused on green recovery methods, which utilize safer reagents, consume less energy and are not complex. In this respect, state of the art hydrometallurgy is conducted in a systematic research utilizing more than 20 spent catalyst samples, using leaching media of HCl (37%), H2O2 (1%v/v) and an additional source of chlorine ions NaCl (99,9%), resulting in recovery rates for Pt, Pd and Rh, namely 100%, 92% and almost 60%, respectively. It is remarkable, that this method is cost effective, as no pretreatment stage is conducted. The recovery rate was validated through X-ray fluorescence spectroscopy analysis (XRF). External calibration mode took place with respect to XRF and ICP-OES measurements. Kinetics of the recovery hydrometallurgical process was also studied, in short intervals, as well as spent catalytic powder characterization through Scanning electron microscopy (SEM), Energy Dispersive X-Ray Spectroscopy analysis (EDS) and X-ray Powder Diffraction (XRD).
Authors : Chiara GIOSUÈ, Alessia AMATO, Michela MENGUCCI, Maria Letizia RUELLO
Affiliations : Università Politecnica delle Marche, Ancona, IT
Resume : The production of WEEE, waste of electrical and electronic equipment, is continuously increasing due to the rapid technological development which has been witnessing in the last decades. WEEE represents the fastest growing category of waste globally. This inevitably leads to the problem of disposing this waste as it is not biodegradable and contains substances that are toxic to the environment. This work arises from the need to move from simple disposal in landfills or incineration, to the valorization of such waste through two paths: recovery and recycling. This research focuses on a single type of WEEE, liquid crystal displays (LCD), which is only now entering its end of life phase. The recovery concept is linked to the Critical Raw Material contained in the LCDs, in particular with reference to Indium, for which a method of extraction from LCDs has already been patented. Sadly the recovery of Indium from LCDs cannot be considered economically sustainable and therefore does not allow us to talk about circular economy. Therefore it is also necessary to focus on recycling the material remaining after Indium recovery, for which the construction sector seems to be very promising fate. The work aims to use LCD waste scraps after the extraction of Indium, in a sustainable way both economically and environmentally, making mortars with these waste as ingredients in substitution of binder and aggregate.
Photovoltaics : Vanira Trifiletti
Authors : Manuel Salado Manzorro
Affiliations : BC Materials
Resume : Perovskites solar cells have irrupted in the photovoltaic field with no precedent. Rising the power conversion efficiencies (PCE) from ~4% to more than 25% can be considered as one possible replacement to silicon solar cells. However, long-term stability together with the lack of a full understanding of the intrinsic processes, limit its up scaling to industry. To overcome those issues, different strategies such as compositional engineering of perovskite material as well as new synthesized hole transport materials (HTMs) were accomplished. As a layered structure, in order to reduce internal losses, an optimized interface between the different layers of the perovskite device is paramount. In this regard, an optimized surface passivation layer is seen as an ideal approach to protect the surface from extrinsic factors, without altering the electro-optical properties. In this work, we present how the utilization of a passivation layer protects the perovskite layer from atmospheric degradation as well as compensate for the possible iodine segregation on the perovskite layer. As result, an improved PCE (20%) was also obtained as the passivation layer lessen trap-states towards the HTM layers, reducing interfaces recombination processes and therefore improving the open-circuit voltage.
Authors : Mihaela Girtan
Affiliations : Photonics Laboratory, (LPhiA) E.A. 4464, SFR Matrix, Université d?Angers, Faculté des Sciences, 2 Bd Lavoisier, 49000 Angers, France, firstname.lastname@example.org
Resume : Since the 50?s different materials and technologies were tested for solar cells manufacturing. Today 90 % of solar cells commercial panels are based on Silicon. However, even if silica is one of the most abundant compound on Earth, due it intensively use, silicon is since 2017 one of 27 critical raw materials for the EU. In order to reduce fabrication cost and increase the energy conversion efficacy, many strategies were considered, such as: new active materials, multi-junction cells (multiple semiconductors stacked cells, intermediate band semiconductors solar cell, up and down converters. Perovskite solar cells based on CH3NH3PbI3 by achieving in less than five years, efficiencies comparable to silicon solar cells, show the potential of these new materials to replace Silicon. In this paper structural, morphological optical and electronical properties of CH3NH3PbI3 thin films deposited by spin coating, with different spin speeds on glass and conductive patterned substrates were investigated in order to achieve a deeper understanding of physical properties of this class of materials. The XRD investigations indicate the formation generally of the cubic phase, or a mixture between cubic and tetragonal phase. The variation of the electrical conductivity at exposure to light in function of time and light intensity and the variation of the electrical conductivity in function of temperature were investigated and interpreted.
Authors : Silvia Varagnolo1, Jaemin Lee1, Houari Amari2 and Ross A. Hatton*1
Affiliations : 1Department of Chemistry, University of Warwick, CV4 7AL, Coventry, United Kingdom 2Department of Physics, University of Warwick, CV4 7AL, Coventry, United Kingdom Current Address: Imaging Center at Liverpool (ICaL), School of Engineering & School of Physical Sciences, University of Liverpool, L69 3GQ, Liverpool, United Kingdom Contact email: Ross.Hatton@warwick.ac.uk
Resume : Photovoltaics (PVs) fabricated by printing at low temperature onto flexible substrates are attractive for a broad range of applications in buildings and transportation, where flexibility, colour-tuneability, light-weight and low cost are essential requirements. Two emerging PV technologies that have strong potential to meet these requirements are organic PVs and perovskite PVs. However, it is widely recognized that these classes of PV can only fulfill their full cost advantage and functional advantages over conventional thin film PVs if a suitable transparent, flexible electrode is forthcoming. Indium-tin oxide (ITO) is currently the dominant transparent conductor used in opto-electronics, including PVs. However, its fragile ceramic nature makes it poorly compatible with flexible substrates and indium has been identified as a ?critical raw material? for the European economic area, due to the high risk of supply shortage expected in the next 10 years. Consequently there is a need to develop a viable alternative to ITO, particularly for utility in PVs where large quantities will be needed in the coming decades to help address the threat posed by global warming. Patterned thin films and grids of the most electrically conductive metals; copper and silver, can perform as well as ITO as a transparent electrode in PVs . This talk will present a new approach to the fabrication of high performance transparent electrodes based on grids of these metals with exceptionally narrow metallised line-width and spacing, and demonstrate utility in high performance organic PVs. These electrodes offer a far-field transparency > 80% and sheet resistance ? 5 Ohms per square on flexible plastic substrates, performance that exceeds that of commercial ITO coated plastic. Conventional methods for fabricating such an electrode involve printing the metal grid from costly colloidal solutions of nanoparticles, or selective removal of metal by etching using harmful chemicals, or electrochemical deposition of the metal grid - which is an inherently chemical intensive and slow solution based process. The new approach described is based on the finding that silver and copper vapor do not condense onto thin films of certain organofluorine compounds, so metal is selectively deposited only where the fluorinated layer is not printed. The beauty of this approach lies in its simplicity and versatility, since vacuum evaporation of metals is a well-established and widely available metal deposition method, and the shape and dimensions of the features deposited are limited only by the printing technique used. This new approach avoids the use of harmful chemical etchants and critical raw elements, and leaves the metal surface uncontaminated.
LED : Jessica Satta
Authors : Pier Carlo Ricci
Affiliations : Dipartimento di Fisica , Universita' di Cagliari
Resume : The lighting sector is living a soft but drastic revolution both in concept design and, hence emitting devices. The global market share of alternatives lighting sources as Light Emitting Devices (LEDs) and Compact Fluorescence Lights (CFLs), will raise from few percentage of the global market share in 2010 to almost 90% in the 2020, increasing from the current value of about US$26 billion (2017) to more than US$72 billion in 2020. In this framework, Critical Raw Materials (CRM), mainly Rare Earths elements assume a fundamental role and do not have alternatives in the current LED technology and as phosphors in general. The development of new emitting elements that are cost effective with improved quantum efficiency and color quality is of highest priority for the next future European market of fluorescent devices. In this talk we will analyze the technical and physical requirements of the phosphors in LED and CFL, and strategies to obtain efficient emitting materials free and/or with reduced contents of CRM. We will discuss new classes of organic phosphors with high stability at high temperature based on Carbon Nitride structures and the achievement of hybrids materials with improved and tunability performance. Hybrid organic/inorganic structures with external inorganic and protective shell, as well reverse structures, with the organic part acting as antenna element for inorganic emitting elements will be showed and discussed.
Authors : P. Gaffuri1-2, M. Salau?n 1, I. Gautier-Luneau 1, G. Chadeyron 3, A. Potdevin 3, E .Appert 2, V. Consonni 2, A. Ibanez 1
Affiliations : 1 Univ. Grenoble Alpes, CNRS, Institut Néel, F-38000 Grenoble, France; 2 Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France; 3 Université Clermont Auvergne, CNRS, SIGMA Clermont, Institut de Chimie de Clermont-Ferrand, F-63000, Clermont-Ferrand, France;
Resume : Despite their high luminous efficacy as well as their low energy consumption that has brought them to the top of the lighting market, the use of rare-earth containing phosphors such as YAG:Ce3+ in white LEDs raises both environmental and geopolitical concerns. Recently, we synthetized yttrium-aluminum borate phosphors without any lanthanide as photoluminescence (PL) metal activator, by using the modified Pechini method. Their PL emission, extended in the whole visible range, arises from polycyclic aromatic hydrocarbon molecules that are trapped in the stable aluminum borate glassy matrix during the synthesis process of the micro-powders. This was evidenced by coupling thermal analyses (DTA, thermogravimetry, mass spectrometry), PL spectroscopy, NMR and EPR measurements. [2-3] Here we present our most recent and promising results on the substitution of yttrium cations, playing the role of glass modifier in the aluminum borate matrix, by non-toxic and abundant zinc cations. This new rare-earth-free phosphor produces broad and intense PL emissions when excited by near-UV LEDs, with high internal quantum yields (around 60%), and very good color rendering index (CRI > 90). Moreover, the PL emission is easily tunable in the visible range, from cold- to warm-white emissions by simply adjusting the final calcination temperature involved at the end of the synthesis process. Thus, these efficient and stable phosphors, only composed of abundant and non-toxic elements open the way for the development of rare-earth-free single phosphor for white LED lighting. 1 V. F. Guimarães et al., J. Mater. Chem. C, 2015, 3, 5795?5802. 2 P. Burner et al. Angew. Chemie - Int. Ed., 2017, 56, 13995?13998. 3 A. D. Sontakke et al. J. Phys. Chem. Lett., 2017, 8, 4735?4739.
Authors : Luigi Stagi, Luca Malfatti, Plinio Innocenzi
Affiliations : Department of Chemistry and Pharmacy, Laboratory of Materials Science and Nanotechnology, CR-INSTM, Via Vienna 2, 07100 Sassari, Italy
Resume : Carbon dots (CDs) are potentially a valid alternative to semiconductor quantum dots or luminescent rare-earth doped materials. In particular, CDs with emissions in the blue/green range are almost competitive with the most common semiconductor nanocrystals and are proposed as low-cost and non-toxic alternatives in many fields of optical technologies. However, many issues still need to be addressed, including the reproducibility of synthesis, low quantum yield at large wavelengths (red emission) and their incorporation into solid matrices without efficiency losses. In this work, we will talk about these problems and the methodological perspectives for overcoming them by engineering new hybrid heterostructures.
Authors : Seung Hee Choi1, Seok Bin Kwon1, Jung Hyeon Yoo1, Seong Guk Jeong1, Hyun Bin Kim1, Jeong Dong In1, Hyung Wook Choi2, Dae Ho Yoon1,2,*
Affiliations : 1 School of Advanced Materials Science & Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Korea; 2 SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SKKU), Suwon 16419, Korea
Resume : Lead halide perovskites (LHPs) have attained great attention as the candidates for optoelectronic devices due to their outstanding optical properties. As the wide color gamut (WCG) of the white LEDs becomes an important issue for more realistic colors in display technology, LHPs having narrow-band emission are emerging. However, improving the stability and synthesis scale of perovskite materials is still challenging. In this study, we report a rapid and large-scale synthesis technique for a green-emitting CsPbBr3/Cs4PbBr4 hybrid halide perovskite composite by generating enormously powerful hydraulic shear. In addition, CsPbBr3 nanocrystals are self-encapsulated in the Cs4PbBr6 matrix during the reaction, deriving the effect of improving stability against external factors that degrade luminescence properties. Through this production method, we not only improved the synthesis scale more than 10 times but also reduced the synthesis time to obtain a CsPbBr3/Cs4PbBr6 hybrid composite within 30 min about 20 times faster compared with the conventional stirring method. To realize the WCG white LEDs, the pure green-emitting hybrid composite having narrow emission spectrum half-width of 19 nm centered at 521 nm and a high photoluminescence quantum yield of 52 % is applied with red-emitting CsPb(Br0.4I0.6)3 perovskite film on a blue InGaN LED, achieving high-performance luminescence characteristics which encompass 119.5 % compared with National Television System Committee (NTSC) value. Therefore, this hybrid composite and synthesis method is expected to be a promising candidate for application in the backlight unit for displays.
Authors : Nils Steinbrück, Max Briesenick, Dennis Meyer, Guido Kickelbick
Affiliations : Saarland University, Inorganic Solid State Chemistry, Campus C4 1, 66123 Saarbrücken, Germany
Resume : Rare earth elements are important components in light conversion materials for LEDs. Principally organic fluorescent molecules are also suited for the down conversion in high power white light LEDs. However, these molecules often reveal thermal- and photobleaching in real LED applications. We report here the development of a novel siloxane-based LED encapsulation material, which allows a highly improved stabilisation of the organic dyes after embedding. The material is formed by a polycondensation reaction of di- and trialkoxysilanes allowing a broad variety of substitution patterns of the siloxane network. With this approach, high decomposition temperatures, high optical transparencies, and controllable refractive indices are possible. In addition, the viscosity can be tuned depending on the requirements of the LED encapsulation process. The crosslinking of the system is based on a thermal process and does not require any catalyst like the currently available systems. The covalent incorporation of fluorescent dyes in the siloxane chain allows for the incorporation of high amounts of dye in the material without loss of optical quality. In our most recent work, we were able to use these materials in an emulsion approach for dye encapsulation in micron-sized powders. Thus, reduction and even replacement of rare earth elements seems possible with the obtained novel materials.
Permanent Magnets and Additive Manufacturing : Aminta Mendoza
Authors : Vladimir V. Popov 1, Ilya Radulov 2, Konstantin Skokov 2, Andrey Koptyug 3, Menachem Bamberger 1
Affiliations : 1 - Israel Institute of Metals, Technion R&D Foundation, Technion City, 3200003, Haifa, Israel 2 - Technische Universit at Darmstadt, Alarich-Weiss-Str. 16, 64287, Darmstadt, Germany 3 - Sports Tech Research Centre, Mid Sweden University, Akademigatan 1, SE-831 25, Ostersund, Sweden
Resume : Additive manufacturing is a novel effective fabrication technique of complex net-shape structures. The modern trend in additive manufacturing is the production of functional materials. One such group of materials that are promising by printing are permanent magnets. However, additive manufacturing of magnets is a challenging goal as specific phase composition and the grain size are required. Current work presents the experimental findings in the additive manufacturing of Mn-Al rare-earth-free permanent magnets.
Authors : Kevin Sartori,1, 2 Fadi Choueikani,2 Alexandre Gloter,3 Sylvie Begin-Colin,1 Dario Taverna,4 Benoit P. Pichon*, 1, 5
Affiliations : 1 Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000 Strasbourg, France 2 Synchrotron SOLEIL, L?Orme des Merisiers, Saint Aubin ? BP48, 91192 Gif-sur-Yvette, France 3 Laboratoire de Physique des Solides, CNRS, Université Paris-Sud UMR 8502, 91400 Orsay, France 4 Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Université, 75005 Paris, France 5 Institut Universitaire de France, 1 rue Descartes, 75231 Paris Cedex 05
Resume : Hard-soft coupled magnetic nanoparticles have gained a tremendous amount of interest during the last decade for short-term development of advanced applications related to spintronics.1 Indeed, they are a potential alternative to produce permanent magnets in order to circumvent supply storages caused by the critical need for rare earth elements in communications and mobility applications. With this purpose, the main goal is to overcome superparamagnetism, which results from size reduction to the nanoscale.3 A very attractive approach is the design of core-shell nanoparticles that display exchange coupling between interfacial spins of hard and soft magnetic phases which result in the significant enhancement of the magnetic anisotropy energy. Ferrites (MFe2O4, with M: Co, Mn, Ni), which exist in several chemical compositions, allow the fine modulation of hardness and softness of the magnetic phases. Nevertheless, core@shell nanoparticles which combine two different ferrites remain superparamagnetic at room temperature. Here, we report on an original strategy to synthesize onion-type nanoparticles that are ferrimagnetic at room temperature and mainly consist of iron oxide with a mean size that does not exceed 16 nm. The significant enhancement of the magnetic properties at room temperature is ascribed to a double interfacial exchange coupling resulting from the Fe3-dO4@CoFe2O4@Fe3-dO4 structure. More details in : Pichon, B. P. et al. J. Am. Chem. Soc. 2019, 141, 9783-9787 1. López-Ortega, A. et al. Phys. Rep. 2015, 553, 1?32. 2. Gutfleisch, O. et al. Adv. Mater. 2011, 23 (7), 821. 3. Nogués, J. et al. Phys. Rep. 2005, 422 (3), 65?117.
Authors : Ester M. Palmero, Daniel Casaleiz, Javier de Vicente, Alberto Bollero
Affiliations : IMDEA Nanoscience, 28049 Madrid, Spain
Resume : Additive manufacturing attracts much interest in technological sectors as it allows for designing and fabricating complex objects with tuned properties . In the permanent magnet (PM) sector the challenge is to develop magnets with high filling factor (FF), while avoiding the deterioration of their PM properties. Improved ferrites and MnAl alloys are promising rare earth-free candidates for plugging the gap between conventional ferrites and NdFeB, provided a successful development of their PM properties . Composites (PM particles/polymer) made of gas-atomized τ-phase MnAlC (industrial collaboration with Höganäs AB, Sweden), Sr-ferrite, NdFeB, and hybrid (Sr-ferrite/NdFeB) powders (mean particle size: 5-50 μm) have been used for extruding magnetic filaments . The combination of materials and particle sizes allowed for obtaining PM filaments with a coercivity ranging between 1.5-10 kOe. Particle size was a key parameter for obtaining flexible filament: fine particles (< 20 μm) and an optimized fine-to-coarse particles ratio lead to filaments with a high FF (> 80%) and non-deteriorated PM properties. As a proof-of-concept, optimized filaments have been used for 3D-printing objects .  L.E. Murr, J. Mater. Sci. Technol. 32, 987 (2016).  A. Bollero et al., ACS Sustainable Chem. Eng. 5, 3243 (2017); J. Rial et al., Acta Mater. 157, 42 (2018).  E.M. Palmero et al., Sci. Technol. Adv. Mater. 19, 465 (2018); Submitted (2019); IEEE Trans. Magn. 55, 2101004 (2019).
Authors : C. Muñoz-Rodríguez, E.M. Palmero, J. Rial, L. Feng, T. Mix, F. Olsson, B. Skårman, H. Vidarsson, P.-O. Larsson, T.G. Woodcock, A. Bollero
Affiliations : C. Muñoz-Rodríguez (IMDEA Nanoscience, Madrid, Spain); E.M. Palmero (IMDEA Nanoscience, Madrid, Spain); J. Rial (IMDEA Nanoscience, Madrid, Spain); L. Feng (IFW Dresden, Institute of Metallic Materials, Dresden, Germany); T. Mix (IFW Dresden, Institute of Metallic Materials, Dresden, Germany); F. Olsson (Höganäs AB, Höganäs, Sweden); B. Skårman (Höganäs AB, Höganäs, Sweden); H. Vidarsson (Höganäs AB, Höganäs, Sweden); P.-O. Larsson (Höganäs AB, Höganäs, Sweden); T.G. Woodcock (IFW Dresden, Institute of Metallic Materials, Dresden, Germany); A. Bollero (IMDEA Nanoscience, Madrid, Spain)
Resume : Nowadays the use of permanent magnets (PM) is increasing in different applications such as energy and transport. In order to obtain a high magnetic performance currently the most extended choice are PMs containing critical raw elements (rare-earths (REs)), which prices fluctuate due to the localized geographical production. Alternatives are investigated to fill the gap between ferrites and NdFeB magnets. MnAl alloy has become a RE-free PM candidate as long as development of the ferromagnetic ?-phase . The theoretical high maximum energy product (BH)max of MnAl is 12 MGOe, with a lower density compared to NdFeB (5.2 vs. 7.6 g/cm3) . Increasing coercivity has been achieved recently by microstructural modification and controlled phase transformation through the flash-milling process [3,4]. In this study, MnAlC bulk magnets were obtained by hot-pressing starting from gas-atomized and flash-milled (60s) powder. We have achieved simultaneously the ?-to-? transformation and a MnAlC bulk magnet under optimal combination of temperature and pressure. By comparison, we applied hot-pressing to ?-phase MnAlC thus validating our single-step approach. These results open the path to new possibilities towards the industrial fabrication of this RE-free PM alternative.  H. Kono, J. Phys. Soc. Japan 13, 1444 (1958).  J.H. Park et al., J. Appl. Phys. 107, 09A731 (2010).  J. Rial et al., Acta Mater. 157, 42 (2018).  J. Rial et al., Engineering (2020). DOI 10.1016/j.eng.2019.03.013
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|08:45||PLENARY SESSION 2|
TCO : Maria Luisa Grilli
Authors : D. Bellet1, D.T. Papanastasiou1, L. Bardet1,2, C. Jiménez1, D. Muñoz-Rojas1
Affiliations : 1 Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, 38000 Grenoble, France (email@example.com) 2 Univ. Grenoble Alpes, CNRS, Grenoble INP, LGP2, 38000 Grenoble, France
Resume : Transparent electrodes constitute a key component in many devices such as solar cells, OLEDs, displays, transparent heaters or smart windows. The currently most well-known and used transparent conductive material (TCM) is indium tin oxide (ITO). However indium scarcity and the lack of flexibility of ITO have prompted the search for alternative low cost and flexible TCM which do not contain any critical raw materials. There has been lately a growing interest for several material technologies. For instance metallic nanowire networks appear promising since they exhibit very promising properties: high optical transparency, very good electrical properties and mechanical flexibility; while solutions have been reported to enhance their stability. Metallic grids and meshes have been also well studied and promising integrations have been reported. In parallel recent reports showed that the electrical conductivity has drastically increased these last years in the case of conducting polymers. Carbon based TCM, such as graphene or carbon nanotube networks, can also be potentially interesting. There is an important role played by the association between these different TCM technologies; there is currently an intensive research on the optimization of these nanocomposites. Finally we will describe what appear to be the future most promising and innovative research directions in the field of emerging TCM for substitution critical raw materials, as well with the main future challenges.
Authors : Rocío Ortiz, Lucía Mendizabal, Leyre Tejedor, Aida Gonzalez, Eva Gutierrez.
Affiliations : Tekniker (Eibar, Spain), Tekniker (Eibar, Spain), Ariño Duglass (Zaragoza, Spain), Ariño Duglass (Zaragoza, Spain), Tekniker (Eibar, Spain).
Resume : Transparent conductive oxide (TCO) coatings can be applied to fast and reliably heat locomotive windscreens and improve the performance of the currently used PVB polymeric foils with embedded tungsten microwires. In this regard, indium tin oxide (ITO) coatings show excellent intrinsic optoelectronic properties and performance but includes indium, a technology-critical element. On the contrary, resources for aluminum doped zinc oxide (AZO) coatings are not critical but these coatings show worse optoelectronic properties due to a lower charge carrier mobility. Therefore, temperature treatments are required for AZO coatings to get properties as good as those shown by ITO coatings. Since applying heating in vacuum coating processes of industrial lines for glass production and processing is time-consuming, coating development at room temperature is quite beneficial in terms of improving the cost-efficiency of the production process. Here, an industrial process has been developed to coat rail glass prototypes with AZO coatings deposited by DC magnetron sputtering at room temperature in combination with a simple annealing process in air, improving the process cost efficiency. The obtained AZO coated glass prototypes met the transmission and conductive requirements set for locomotive windscreens, showing a transmission higher than 70% and a sheet resistance around 20 ?/cm. More importantly, the developed process can be easily reproduced in any type of conventional sputtering system and heating chamber, ensuring the scale-up of the process for industrial glass manufacturing. It is worth to highlight that this developed magnetron sputtering deposition process combined with the annealing treatment could be potentially integrated in industrial lines for tempered and/or laminated glass processing.
Authors : Mihaela Girtan-1, Romain Mallet-2, Marcela Socol-3, Anca Stanculescu-3
Affiliations : 1- Photonics Laboratory, (LPhiA) E.A. 4464, SFR Matrix, Université d?Angers, Faculté des Sciences, 2 Bd Lavoisier, 49045 Angers, France, 2- SCIAM, SFR ICAT, Université d?Angers, 4 Rue Larrey, 49033 Angers, Cedex 09, France, 3- National Institute of Material Physics, 405A Atomistilor Street, 077125 Bucharest-Magurele, Romania, firstname.lastname@example.org
Resume : PEDOT:PSS is one of few organic transparent conducting semiconductors which can be used as electrode for OLED, organic or perovskite solar cells. In this paper a complete characterization from optical, morphological, electrical, photo-electrical and thermo-electrical point of view was done for PEDOT:PSS thin films and DMSO and EG sensitized PEDOT:PSS films. The studies on the electrical conductivity and electrical photoconductivity allowed the calculation of different relaxation times. The relaxation time of the electrical conductivity is or order of femtosecond and is multiply by a factor 10 when PEDOT:PSS thin films were deposited on surfaces sensitized with DMSO and EG. Besides, the photoconduction excitation and relaxation times are of order of seconds. An increase of the relaxation photoconduction time by 2 was observed for films deposited on surfaces sensitized with DMSO and by 1.2 for films deposited on surfaces sensitized with EG. The time response of electrical conductivity after exposure to light add supplementary knowledge for the understanding of the inertial processes, or hysteresis behavior of organic or perovskite solar cells involving PEDOT:PSS films. The electrical conductivity increase with the temperature and the use of DMSO and EG as surfactants lead to higher values of electrical conductivity and Seebeck coefficient. A better stability of the electrical conductivity with the temperature increase, was remarked for films deposited on surfaces sensitized with DMSO.
Authors : S. Iftimie1,*, D. Coman1, C. Locovei1,2, A. Radu1, V.A. Antohe1,3, A. Dumitru1, M. Manica1, C. Radu1, L. Ion1, and S. Antohe1,4
Affiliations : (1)University of Bucharest, Faculty of Physics, Bucharest, Romania; (2)National Institute of Materials Physics, Magurele-Bucharest, Romania; (3)Catholic University of Louvain, Institute of Condensed Matter and Nanoscience, Louvain-la-Neuve, Belgium; (4)Academy of Romanian Scientists, Bucharest, Romania
Resume : We discuss the effects of annealing on the physical properties of radio-frequency sputtered indium tin oxide (ITO) thin films, grown onto optical glass substrates. Two types of thermal treatments were performed denoted here in-situ and ex-situ. The in-situ one consisted in intentionally heating the samples? substrate during the deposition process, while the ex-situ annealing was made using an oven at 200°C, 300°C and 400°C, respectively. The structural, optical, morphological, and electrical properties of fabricated samples were discussed in terms of pristine ones. Both in-situ and ex-situ thermal treatments improved the crystalline arrangement of ITO thin films, although no significant changes were observed on their optical properties. By evaluating the Skewness parameter was determine that the annealing affects the planarity of samples. The electrical behavior was analyzed by Van der Pauw measurements in the ranges of 300 K ? 10 K and it showed that by the ex-situ thermal treatment the electrical resistivity values were increased, most likely due to the increase of the density of oxygen vacancies. Keywords: indium thin oxide, radio-frequency magnetron sputtering, thermal treatment, annealing Acknowledgments: This work was financially supported by the Romanian National Authority for Scientific Research, UEFISCDI, under the project 18PCCDI/2018 and project 40PCCDI/2018.
Magnetism and Magnets : Benoit Pichon
Authors : A. Lappas (1,*), G. Antonaropoulos (1,2), K. Brintakis (1), M. Vasilakaki (3), K.N. Trohidou (3), V. Iannotti (4), G. Ausanio (4), A. Kostopoulou (1), M. Abeykoon (5), I.K. Robinson (6,7) and E.S. Bozin (6)
Affiliations : (1) Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, Vassilika Vouton, 71110 Heraklion, Greece; (2) Department of Chemistry, University of Crete, Voutes, 71003 Heraklion, Greece; (3) Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, 15310 Athens, Greece; (4) CNR-SPIN and Department of Physics "E. Pancini", University of Naples Federico II, Piazzale V. Tecchio 80, 80125 Naples, Italy; (5) Photon Sciences Division, National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, 11973 NY, USA; (6) Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA; (7) London Centre for Nanotechnology, University College, London WC1E 6BT, UK.
Resume : Among the most critical aspects of relevance to biomedical applications of nanoscale crystals is their size-mediated functionality in the cellular environment . Here, we combine nanochemistry, detailed characterization and Monte Carlo simulations to explore the relation of size and shape on nanoscale surfaces and interfaces emerging in core-shell iron-oxide nanocrystals, while we also discuss those imperfections that assist magnetic properties relevant to nanobiotechnology . Connecting compositional complexity and nanomagnetism allows us to gain insights on how controlled cation vacancy-induced disorder tailors physical properties, including exploitable thermal energy transfer for small-size magnetic nanocarriers. Synchrotron X-ray total scattering experiments corroborate our idea that size-dependent evolution of the metal-cation valence state, produces pinning defects which promote favorable magnetic exchange interactions at subcritical sizes (< 10 nm), and importantly beyond the limitations of finite-size effects alone. We offer a description of atomic interaction effects and knowledge of the different length-scale mechanisms required to facilitate the performance of single-crystal nanoscale particles as functional nanoheaters.  D. Yoo et al., Acc. Chem. Res. 44, 863, (2011).  A. Lappas et al., Phys. Rev. X 9, 041044 (2019).
Authors : Seong Won Cho, Jeehoon Jeon, Seungwo Han, Hyun Cheol Koo, Suyoun Lee
Affiliations : Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 02792, Korea; Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Korea; Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea
Resume : The Rashba spin-orbit coupling (SOC) is one of ingredients to realize a novel spintronic device because it enables manipulating the magnetic properties of a material via electric field, leading to a dramatic reduction in energy consumption. In this regard, GeTe is very attractive due to its extremely high Rashba constant ~4.2?10-10eV*m. In addition, its ferroelectricity at room temperature makes GeTe more special raising its potential to be applied in spintronic non-volatile memory devices. Nevertheless, its magnetotransport properties are not much explored yet. In this work, we present the growth of high-quality epitaxial GeTe thin films by thermal evaporation technique and its magnetotransport properties with varying thickness. From the analysis of the temperature dependence of the weak antilocalization (WAL) effect, it is found that the large SOC survives up to room temperature.
Authors : Y. Hernandez, Carlos A. Palchucan, Ligia E. Zamora, G. A. Pérez Alcázar
Affiliations : Grupo de Metalurgia Física y Teoría de Transiciones de Fases, Facultad de Ciencias, Universidad del Valle Cali Colombia
Resume : In this paper we present and analyze the results of the structural and magnetic properties of the Fe3Sn system when Sn is replaced by Si. Fe3Sn is known to be a potential material to obtain a permanent magnet free of rare earths. Samples of Fe3Sn1-xSix with x = 0.00, 0.05, 0.10, 0.15, and 0.20 were prepared by solid state reaction. The experimental techniques used for the characterization were vibrating sample magnetometry (VSM), X-ray diffraction (XRD), Mössbauer spectrometry (MS) and magnetic thermogravimetry analysis (TGA). The VSM analysis showed that all samples are magnetically soft, and the highest values were: saturation magnetization Ms = 134 Am2 / kg, coercive field Hc = 5.19 mT and the anisotropy constant K1 = 1.48 MJ / m3 for the sample x = 0.20. The X-ray patterns of the samples were refined with a Fe3Sn hexagonal phase, and the two cubic phases of SiFe and FeSn (Fe surrounded by different Sn environments). From the obtained results, it can be concluded that Si is soluble in the Fe3Sn matrix a concentration of 15 %, and above this it begins to segregated in this matrix. Using the Mosfit program, the Mössbauer spectra were fitted with 3 sextets and a doublet associated with the Fe3Sn, FeSn (Fe surrounded by different Sn environments) and SiFe phases, respectivelly. From the thermogravimetric analysis it was shown that the samples have two magnetic transitions associated with the Fe3Sn and FeSn phases, respectively, a result that coincide with the fitted made in the Mössbauer spectra.
Critical Raw Materials and Recycling : Pier Luigi Franceschini
Authors : Alessandra Hool
Affiliations : ESM Foundation, Junkerngasse 56, 3011 Bern, Switzerland
Resume : Critical raw materials are crucial as enablers for important innovative shifts in key technologies such as energy generation and storage, mobility, and information technology. Securing material supply is thus of high importance for competitive economies. Although Europe possesses limited raw material deposits of certain kinds, their exploration and extraction are often challenging, not least because of a frequently densely populated area and a highly regulated environment limiting the possibilities of domestic primary sourcing. In parallel, a more circular economy is envisaged on EU level ? in order to be economically competitive, but also due to a strive towards an efficient resource management, i.e. less waste, lower carbon footprints, and less negative global impacts in the products? value chains. Thus, numerous initiatives and projects are making efforts towards closing material loops and investing in areas such as recycling or more resource-efficient product design in order to meet both goals: increasing supply independence as well as sustainability. However, these initiatives ? although frequently successful and promising ? are often still scattered undertakings. In particular, materials flows and leakages in the circular economy system are poorly understood. In the future, it will be crucial to define objectives on how to competently and responsibly manage raw materials along the whole value chain, and how to close material loops on different levels. Reliable data and effective policy interventions are needed and require improved collaboration of all involved actors not only in isolated economies, but also internationally.
Authors : B. Sotillo, L. Alcaraz, F. A. López, P. Fernández
Affiliations : B. Sotillo; P. Fernández Department of Materials Physics, Faculty of Physics, Complutense University of Madrid, Madrid, Spain L. Alcaraz; F. A. López National Centre for Metallurgical Research (CENIM-CSIC), Avda. Gregorio del Amo 8, 28040 Madrid, Spain
Resume : Two main problems faced by the increasingly technological society are the huge amount of waste that humans generate and the scarcity or criticality of many of the materials used. In this sense, one of the EU's priorities is to promote the transition to a circular economy, where the materials and products manufactured with them are kept in the life cycle as long as possible. Among the strategic materials, Niobium, Tantalum and Rare Earth Elements (REE) are included in the 2017 year list of the 27 critical raw materials of European Union due to their importance for high-tech products and emerging innovations and the risk in the security of supply and economic importance. In this work, the oxides of two of these strategic materials, Niobium and Tantalum, are recovered from the tailings of the Penouta Sn?Ta?Nb deposit (located in Galicia, Spain) via hydrometallurgical route . The recovered oxides have been used to obtain micro- and nanostructures by a simple thermal evaporation method. The structures have been characterized by means of X-ray diffraction, scanning electron microscopy, luminescence and Raman spectroscopy. The possibility of using these micro- and nanostructures for optical, sensing and energy storage applications will be discussed and related to the crystal structure of the oxides obtained [2,3].  F. López, et al. (2018) Minerals 8, 20.  C. Nico, et al. (2016) Progress in Materials Science 80, 1-37.  S. Xia, et al. (2018) Nano Energy 45, 407-412.
Authors : Sorina Valsan*, Anca Elena Slobozeanu*, Valentin Dragut*, Maria Luisa Grilli** Antonio Rinaldi**, Daniele Valerini**, Mythili Prakasam***, Alain Largeteau***, Radu R. Piticescu*, Arcadie Sobetkii****
Affiliations : * National R&D Institute for Nonferrous and Rare Metals-IMNR, 102 Biruintei Blvd, Pantelimon, Ilfov, Romania ** ENEA Cassacia Research Centre, Rome, Italy *** CNRS-Institute for Chemistry of Condensed Materials, Bordeaux, France) **** MGM Star Construct srl Bucharest, Romnia
Resume : During recent years it was demonstrated that co-doping of zirconia ceramics with different REOs may improve thermal properties of thermal barrier coatings and ionic conductivity of SOFCs at moderate temperatures. In the first part we present the results of thermodynamic prediction for design of zirconia-based ceramics doped with mixed rare earth oxides obtained from monazite concentrates. Starting from the predictive studies performed, zirconia ceramics doped with naturally occurring REOs mixtures have been prepared by hydrothermal synthesis and used as targets for obtaining ceramic coatings on high refractory Ni alloys by EB-PVD and RF sputtering. The thermal stability and mechanical properties of coatings are discussed vs. microstructure characteristics obtained from XRD and SEM/EDAX analysis in order to assess their ability to reduce the use of critical raw materials in extreme temperatures for energy generation. REOs-doped zirconia sintered materials with > 99% theoretical density have also been obtained by spark plasma sintering, demonstrating that using mixed REOs as dopant increase the thermal conductivity and reduce the activation energy for the ionic conductivity in the range of 0.584 ? 0.889 eV for REOs doped ZrO2 compared to 0.718 ? 0.907 eV for 8YSZ standard. First results on single phase solid solution high entropy oxides formation in the system LaxSmxGdxYbxNdx)O (x=0.2) by hydrothermal synthesis and thermal treatment at 12000C are also reported. Acknowledgement: Research financed in the frame of ERAMIN II-COFUND programme, grant ID 87, financed by UEFISCDI Romania, MIUR Italy and ANR France and networking support from COST Action CA 15102 CRM Extreme.
TCO : Maria Luisa Grilli
Authors : Jessica L. Stoner, Philip A. E. Murgatroyd, Marita O'Sullivan, Matthew S. Dyer, Troy D. Manning, John B. Claridge, Matthew J. Rosseinsky, Jonathan Alaria
Affiliations : Department of Physics, University of Liverpool; Department of Physics, University of Liverpool; Department of Chemistry, University of Liverpool; Department of Chemistry, University of Liverpool; Department of Chemistry, University of Liverpool; Department of Chemistry, University of Liverpool; Department of Chemistry, University of Liverpool; Department of Physics, University of Liverpool
Resume : Correlated metallic transition metal oxides offer a route to thin film transparent conductors that is distinct from the degenerate doping of broad band wide gap semiconductors. By exploiting control of the filling, position and width of the bands derived from the B site transition metal in ABO3 perovskite oxide films, we show that pulsed laser deposition-grown films of cubic SrMoO3 and orthorhombic CaMoO3 have superior transparent conductor properties to SrVO3. The increased carrier concentration offered by the greater bandfilling in the molybdates gives higher conductivity while retaining sufficient correlation to keep the plasma edge below the visible region. The reduced binding energy of the n = 4 frontier orbitals in the second transition series materials shifts the energies of oxide 2p to metal nd transitions into the near-ultra violet to enhance visible transparency. The A site size-driven rotation of MoO6 octahedra in CaMoO3 optimizes the balance between plasma frequency and conductivity for transparent conductor performance. We have demonstrated that by using the three chemically controllable parameters of carrier density, orbital energy and bandwidth we can tune the charge transfer band position, plasma frequency and conductivity to optimize the transparent conductor performance of non-toxic, earth abundant Mo-based correlated metal perovskite oxides to match the best-in-class wide band gap semiconductors.
Authors : Anil Kumar, P.P. Sahay
Affiliations : Department of Physics, Motilal Nehru National Institute of Technology Allahabad, Prayagraj-211 004, India.
Resume : Electrochromic smart windows are at the forefront of emerging energy-saving advances in building technologies. Many transition metal-oxide films have been used as electrochromic films as they change their optical transmittance upon charge insertion or extraction. Here, some recent findings on the electrochromic performance of spray-pyrolysed Mo-doped WO3 films  and W-doped MoO3 films , and dip-coated W-doped Nb2O5 films  have been reported. The spray-pyrolysed WO3 films doped with 5 at% Mo exhibit fastest switching response and highest colouration efficiency. It has been concluded that the 5 at% Mo-doped WO3 films have an optimal electrochromic performance, and therefore have the potential to be used as an effective electrochromic film for smart windows. The 3 at% W-doped MoO3 films exhibit maximum colouration efficiency and optimum electrochemical stability whereas the 1 at% W-doped films show optimal reversibility as well as good switching response. The dip-coated 3 at% W-doped Nb2O5 films exhibit the best coloration efficiency 68.7 cm2/C at 600 nm. All the Nb2O5 films show excellent electrochemical stability, and the switching response of the film improves upon W doping. 1. Anil Kumar, Chandra Shekhar Prajapati, P. P. Sahay, Journal of Sol-Gel Science and Technology, 2019 90, 281-295. 2. Anil Kumar, Chandra Shekhar Prajapati, P. P. Sahay, Materials Science in Semiconductor Processing, 2019 104, 104668 (12 pages). 3. Anil Kumar, P. P. Sahay, Journal of Materials Science: Materials in Electronics, 2019 30, 17999?18014.
Batteries : Barbara Mecheri
Authors : Ander Reizabal, R. Gonçalves, C. M. Costa, Leyre Pérez, Jose-Luis Vilas, S. Lanceros-Mendez
Affiliations : BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, 48940 Leioa, Spain. Macromolecular Chemistry Research Group (LABQUIMAC). Dept. of Physical Chemistry. Faculty of Science and Technology. University of the Basque Country (UPV/EHU), Spain. Center of Physics, University of Minho, 4710-058 Braga, Portugal Center of Chemistry, University of Minho, 4710-058 Braga, Portugal Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
Resume : Batteries are essential elements for storing the energy obtained from renewable systems, in particular, lithium-ion due to their higher energy and power density in comparison with other battery systems. One of the main issues that should be improved in thise tipy of batteries are their materials availability, safety and cost. The challenge, is the use of materials with low environmental impact. The separator, one of the main parts of Li-batteries is typically constituted by a polymeric membrane soaked in the electrolyte solution, considering the environmental impact of these synthetic polymers, conventional separators are substituted by natural polymers. In this work, Silk Fibroin (SF) is proposed due to its good mechanical and thermal properties, good processability and biodegradability. Considering that the separator?s pore structure is a critical design parameter once it affects the true length of the ionic path, the goal of the present work is to prepare porous membranes based on SF through the solvent casting salt leaching method with the same degree of porosity but different pore size, allowing to optimize the performance of SF separator membranes. Further, the processing method is highly reproductive and scalable and allows to obtain three-dimensional separators with interconnected pores with sizes ranging from 22 to 250 ?m. Polymer phase, thermal and mechanical properties, contact angle and uptake value were analyzed, showing a correlation between pore size, ?-sheet conformation and discharge capacity value for the prepared SF separators.
Authors : Matthew Zervos (a), Andreas Othonos (b), Marios Sergides (b), Theodore Pavloudis (c), Jospeh Kioseoglou (c)
Affiliations : (a) Nanostructured Materials and Devices Laboratory, School Of Engineering, University Of Cyprus, PO Box 20537, Nicosia, 1678, Cyprus. (b) Laboratory of Ultrafast Science, Department Of Physics, University Of Cyprus, PO Box 20537, Nicosia, 1678, Cyprus (c) Department of Physics, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece.
Resume : Cu3N is an earth abundant, metal nitride, which has a cubic a-ReO3 crystal structure with a lattice constant of 3.8 Å and space group Pm3m, number 221, similar to the ABX3 anti-perovskite structure with a vacant body-center position, so it can readily accommodate impurities and is a defect tolerant semiconductor. In addition it is a p-type semiconductor with an indirect energy band gap of 1.6 ev which makes it attractive for solar cells. Despite ongoing efforts into the growth of Cu3N only a few have measured its optical properties and understood them in terms of the electronic band structure. To the best of our knowledge no one has ever investigated this novel material by ultrafast pump-probe spectroscopy (UPPS) which is a novel method capable of detecting mid gap states in the energy band gap related to structural imperfections. Here we have prepared Cu3N via the direct nitridation of Cu deposited on fused SiO2 under NH3 : O2 at elevated temperatures and investigated its optical properties by UPPS in conjunction with theoretical calculations of the electronic structure. We observe fine spectral features at wavelengths and energies in a reproducible fashion that are in excellent agreement with theory confirming that this is indeed a defect tolerant semiconductor. These results are very important and highlight the way towards a deeper understanding of this novel material not just in the form of films but also in the form of nanostructures which is an essential step towards the realization of energy conversion and storage devices such as solar cells and batteries that are made from earth abundant elements
Authors : Anil Kumar and P.P. Sahay
Affiliations : Anil Kumar Research Scholar Department of Physics, Motilal Nehru National Institute of Technology Allahabad, Prayagraj-211 004, India. Dr. P.P. Sahay Professor Department of Physics, Motilal Nehru National Institute of Technology Allahabad, Prayagraj-211 004, India.
Resume : Thin films of V2O5 have been used in energy storage/conversion systems which include electrochromic devices, rechargeable lithium-ion batteries, pseudocapacitors, etc. The electrochemical properties of V2O5 films are affected greatly by the inlay of appropriate dopants such as Mn, Ag, Cu, and Ti into its matrix. In the present investigation, the V2O5 thin films were prepared via dip-coating method by controlled hydrolytic polycondensation of the vanadium(V) oxytriisopropoxide (VO(OC3H7)3) in isopropanol. For Ti doping, titanium (IV) isopropoxide (Ti(OC3H7)4) was used. The as-deposited films after thermal treatment at 500°C under ambient air for 30 minutes were subjected to characterizations for their structural, morphological and electrochromical properties. The X-ray diffraction (XRD) analyses of the films confirm an orthorhombic phase of vanadium pentaoxide (PDF # 41-1426) which is also supported by Fourier transform infrared (FTIR) analyses. The analyses of electrochromic properties of the films reveal that the 5 at% Ti-doped film has the fast switching time (colouration time: 0.59 s and bleaching time: 0.42 s), highest net charge density and good electrochromic reversibility. Thus, the 5 at% Ti-doped V2O5 film is a fast colour switching film with the optimum switching speed that makes it a potential candidate for electrochromic smart windows.
Authors : Mohammed Bilal 1,2, Bassem Salem 2, Vicent Consoni 3, Hervé Roussel 3, Alexandra Garraud 1, Skandar Basrour 2, Ahmad Bsiesy 1
Affiliations : 1-LTM Laboratory, Univ. Grenoble Alpes, CNRS, CEA/LETI Minatec, LTM, Grenoble, F-38054, France 2 -Univ. Grenoble Alpes, CNRS, Grenoble INP*, TIMA, 38000 Grenoble, France 3-LMGP Laboratory, Univ. Grenoble Alpes, CNRS, Grenoble INP, LMGP, F-38000 Grenoble, France
Resume : The discovery of ferroelectricity in doped hafnium oxide thin films has turned it into one of the leading CMOS-compatible lead-free materials used to replace PZT. Ferroelectric hafnium oxide can open the way to the design of new devices in multiple fields like ferroelectric memories, negative capacitance field effect transistors (FET), pyroelectric sensors or microsystems. Doping is key to stabilize the ferroelectric phase. In this work, hafnium zirconium oxide thin films have been obtained by nitrogen plasma RF sputtering of Hf0.5Zr0.5O2 (HZO) monotarget, unlike the majority of published reports that use co-sputtering. In addition, different deposition conditions have been investigated (e.g. addition of O2 plasma, RF power w or w/o capping electrode) as well as various post-deposition annealing. Thickness ranges from 13 nm to 28 nm, lightly thicker than those reported in the literature. We studied the physical, structural and electrical properties of HZO films incorporated in metal-insulator-metal stacks. All HZO films showed ferroelectric behavior even those of highest thickness as evidenced by 1) the apparition of an orthorhombic phase in XRD analysis, and 2) the P-E (polarization-electric field) hysteresis loop.
Photovoltaics : Manuel Salado
Authors : Vanira Trifiletti
Affiliations : School of Engineering and Materials Science (SEMS), Queen Mary University of London, Mile End Road, London E1 4NS, UK
Resume : At the end of 2017, roughly 1.8% of the worldwide electricity came from solar photovoltaics (PV), which is foreseen to have a crucial role in all significant future energy scenarios with an installed capacity around 5 TW by 2050. Although silicon solar cells currently rule the PV market, the extremely more versatile thin film-based devices (mainly Cu(In,Ga)Se2 and CdTe ones) have almost matched them in performance and they present room for improvement. The low availability of some elements in the present commercially available PV technologies and the recent sharp fall of silicon module price below 1 $/Wp focused the attention of the scientific community on cheap earth-abundant materials. In this framework, thin-film solar cells based on Cu2ZnSnS4 (CZTS) and the related sulphur selenium alloy Cu2ZnSn(S,Se)4 (CZTSSe) were actively investigated in the last ten years. More recently, chalcogenide PV absorbers potentially able to face TW range applications better than CZTS and CZTSSe due to the higher abundance of their constituting elements are getting considerable attention. They are based on both MY2 (where M = Fe, Cu, Sn and Y = S and/or Se) and Cu2XSnY4 (where X = Fe, Mn, Ni, Ba, Co, Cd and Y = S and/or Se) chalcogenides.* An extensive review of emerging earth-abundant thin-film solar cells based on both MY2 and Cu2XSnY4 species will be given, with particular attention to iron-based photovoltaics. * Le Donne, A.; Trifiletti, V.; Binetti, S. New earth-abundant thin film solar cells based on chalcogenides. Frontiers in Chemistry 2019, 7.
Authors : JungHyeon Yoo a, SeungHee Choi a, SeokBin Kwon a, Hyun Bin Kim a, SeongGuk Jeong a, HyungWook Choi b, DongIn Jeong a, DaeHo Yoon a b *
Affiliations : a School of Advanced Materials Science & Engineering, Sungkyunkwan University, Suwon 16419, Korea; b SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan Univerisity (SKKU), Suwon 440-746, Republic of Korea
Resume : Halide perovskites have high potentials to light-emitting applications due to the excellent luminescence properties and relatively facile synthesis method comparing with other phosphors. And the colloidal state of perovskite can be a good advantage for application in the inkjet-printing technique because facile to making inks by high dispersivity in an organic solvent. By applying the inkjet-printing technique to the perovskite, a micro-patterned thin layer and fine devices can be realized more easily compared with conventional production methods. But inkjet printing requires the drying process and the result of that, mixed halide red perovskite have limitations to apply in inkjet printing due to the low drying stability. Herein, we report the improvement of drying stability for red perovskite by inducing aggregation during the drying process for security and double anti-counterfeiting application. Silane ligand is applied to induce the aggregation and optimized depends on the synthesis and purification conditions. The drying stability successfully improved compared with the conventional red perovskite, and improved perovskite is printed on the ethyl-cellulose(EC) spin-coated glass substrate or EC-based films to stabilize the dot. By printing a certain pattern with red and green perovskites, this technique can apply to security and anti-counterfeiting application by complexing the code and also can fabricate the flexible pattern printed film.
|18:30||AWARD CEREMONY followed by SOCIAL EVENT|
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|08:45||PLENARY SESSION 3|
LED : Pier Carlo Ricci
Authors : M. Zukalova, J. Prochazka, A. Zukal, L. Kavan
Affiliations : J. Heyrovský Institute of Physical Chemistry, Czech Acad. Sci.;HE3DA, s.r.o.; J. Heyrovský Institute of Physical Chemistry, Czech Acad. Sci.; J. Heyrovský Institute of Physical Chemistry, Czech Acad. Sci.;
Resume : Limited Co resources together with its toxicity and increasing price stimulated research of the Ni-enriched LiNixMnyCozO2 (x+y+z=1) materials. In general, Ni-rich materials show excellent rate capability and high capacity; however, they experience capacity loss when charged to higher potentials. HE3DA company patented a unique concept of 3D accumulators. The active material has a morphology of hollow spheres with a wall thickness of maximum 10 micrometers. This structure enables the use of thicker, binder-free electrodes, which are made from active material by pressing. Electrochemical performance of the materials NMC333, NMC622 and NMC532 with hollow spheres morphology was evaluated both on a thin electrode and in a 3D arrangement in the battery module. Cyclic voltammetry of Li insertion provided charge capacities of 124, 154 and 142 mAh/g, respectively for thin electrodes containing NMC622, 532 and 333, respectively. Whereas evaluation on a thin electrode did not reveal pronounced differences between particular samples, electrochemical testing of the corresponding battery modules proved higher capacity losses during formatting for the modules containing Ni-rich materials NMC622 and NMC532. This behavior was ascribed to higher reactivity of Ni4+ during charging and higher amount of graphite on anode, consuming larger amount of electrolyte during SEI formation. This work was supported by the Ministry of Industry and Trade of the Czech Republic (contract TRIO FV20471).
Authors : Satta, J. *(1), Carbonaro, C.M. (1), Salado, M. (2), Salazar, D. (2), Ahmad, S. (2), Ricci, P.C. (1)
Affiliations : (1) Dipartimento di Fisica, Università di Cagliari, sp. N°8 Km 0.700, 09042, Monserrato, Cagliari, Italy; (2) Basque Center for Materials, Applications and Nanostructures (BCMaterials), Bld. Martina Casiano UPV/EHU Science Park, Barrio Sarriena s/n, 48940, Leioa, Spain
Resume : Metal halide perovskites is a class of crystalline compounds which have garnered great interest in the recent years. Thanks to their intrinsic properties: high absorption coefficients, high photoluminescence quantum yield, high charge-carrier mobilities, band gap tunability, narrow-band emission, they show great prospective in different applications such as lasers, photodetectors, light emitting diodes. However, most of the recent studies are dedicated to increase their stability and lifetime in real operation conditions. Phase transitions among different polymorphs have been observed depending on temperature, light flux and/or atmospheric stresses (oxygen, moisture and heat). The high temperature phase is a cubic perovskite, with high efficiency and narrow emission line. Unfortunately, for all the members of the group of caesium lead trihalides perovskites, the cubic phase is metastable at room temperature and spontaneously converts to an orthorhombic phase, characterized by a wide band gap and weak and broad emission. In order to stabilize the cubic phase in CsPbI3, we studied the synthesis? conditions of Cs4PbI6 and its role in stabilizing caesium lead iodide perovskite at room temperature.
Authors : G. K. Mussabek, K.K. Dikhanbayev, V.A. Sivakov, Yu. Timoshenko
Affiliations : al-Farabi Kazakh National University, Physical and Technical Department, Almaty, Kazakhstan Leibniz Institute of Photonic Technology, Jena, Germany National Research Nuclear University MEPhI, Phys-Bio Institute, Moscow, Russia Lomonosov Moscow State University, Department of Physics, Moscow, Russia
Resume : Luminescent properties of heterostructures based on porous GaP (por-GaP) and aluminum-doped zinc oxide (AZO) were investigated. Por-GaP was prepared by electrochemical etching of p-type c-GaP wafers and AZO films were deposited by magnetron sputtering on the top of por-GaP layers in order to obtain the diode-like hetero-junction structure. Both the electroluminescence (EL) and photoluminescence (PL) in por-GaP/AZO structures were investigated at room temperature. The PL intensity was dependent on the preparation conditions and it was maximal for po-GaP with porosity of 40-50%, and mean pore diameter of about 200 nm. Por-GaP/AZO structures exhibited red-orange EL, which was related to the radiative recombination of charge carriers in por-GaP layer and at the por-GaP/AZO interface. The obtained results indicate that por-GaP/AZO heterojunction are promising for photonics and LED applications.
Authors : Seok Bin Kwon, Mong Kwon Jung, Seung Hee Choi, Jung Hyeon Yoo, Hyung Wook Choi, Dong In Jeong, Seong Guk Jeong. Hyun Bin Kim, Dae Ho Yoo
Affiliations : School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea; SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Republic of Korea
Resume : The light emitting materials such as perovskite, quantum dots and commercialized phosphors have attracted attention from the world because of their excellent optical properties. However, these materials require various organic solvents, high temperature, high pressure and gas in the synthesis process. Here the metal halide complex was synthesized using by lyophilization assisted recrystallization (LRC) method. In addition, the material does not contain toxic metal such as lead and cadmium, and confirmed green luminescence arised from d5 configuration with the d-d transition of halogen anion coordinated manganese complex in the new structure Cs3MnX5 (X = Br, I). The synthesized Cs3MnBr5 and Cs3MnI5 show narrow band emission (full width at half maximum (FWHM) = 39 and 42 nm) at the center wavelength of 520 and 540 nm, and exhibit high photoluminescent quantum yield (PLQY) of 74.9 and 78.5% under the blue excitation, respectively. We expect this material to be selected as a luminescent material that can replace commercial green phosphors.
Optics : Maria Luisa Grilli, Mihaela Girtan
Authors : Svetlana Neretina, Robert Hughes, and Arin Preston
Affiliations : University of Notre Dame, Notre Dame, IN, United States
Resume : The stability and durability of plasmonic materials is a subject of fundamental importance that can decide whether a technology is viable, reliable, and sustainable. Such considerations become amplified for plasmonic applications requiring that the nanostructures operate at elevated temperatures. With plasmonics being a field of study that is powered by the ability to shape- and size-engineer metals at the nanoscale, the tendency for these same structures to oxidize and morphologically reconfigure when heated can disrupt or destroy properties that were so carefully engineered in the first place. Here, we report on a strategy capable of yielding substrate-based plasmonic nanostructures that are robust to oxidation, etchants, and high temperatures. It is reliant on the formation of substrate-immobilized single-crystal nanostructures to which an ultrathin protective cladding is applied. It will be shown that suitably clad Au structures with far from equilibrium geometries are able to maintain their shape at temperatures as high as 800 °C. Using the same cladding, Cu structures are resistant to oxidation in air at temperatures as high as 600 °C. In both cases, the plasmonic properties, while modified by the application of the cladding, remain unchanged when heated. Together, the work provides a fundamental understanding of high-temperature diffusion processes occurring for clad metals and advances the processing science needed to manufacture durable plasmonics.
Authors : H. Ferhati1 and F. Djeffal1,2,*
Affiliations : 1 LEA, Department of Electronics, University Mostefa Benboulaid-Batna 2, Batna 05000, Algeria. *E-mail: email@example.com, firstname.lastname@example.org, Tel/Fax: 0021333805494
Resume : This work aims to investigate the performance of a new Junctionless (JL) Ge-gate Tunneling-FET phototransistor for Infrared sensing applications. The electrical and optical performances of the considered sensor are numerically analyzed, where both switching and optoelectronic properties are reported. In this context, we address the influence of the Ge-gate doping level and high-k gate dielectric on the variation of optical Figures of Merit (FoM) parameters such as responsivity, ION/IOFF ratio and optical commutation speed. Interestingly, it was revealed that the proposed design provides promising pathways for enhancing the phototransistor FoMs as compared to the conventional FET-based sensors. In the second stage of our investigation, we provide a performance assessment of the proposed phototransistor by analyzing its switching capabilities as compared to the conventional design, where the device is implemented in an optical inverter circuit. The obtained results indicate the superior optoelectronic performance offered by the proposed design in comparison with the conventional devices in terms of optical commutation speed and optoelectronic gain. Therefore, this contribution can provide more insights concerning the benefit of adopting JL-TFET design for future high-performance and ultra-low power deep submicron CMOS optoelectronic applications.
Authors : S.Ben Hassine, S.Ridene
Affiliations : Laboratoire de Matériaux Avancés et Phénomnes Quantiques, Faculté des Sciences de Tunis, Université de Tunis El Manar, Campus Universitaire, 2092 Tunis, Tunisia
Resume : In this paper, we present a comprehensive set of computations of effective mass theory for both the Kane's parabolic band approximation and Luttinger-Kohn's valence band mixing approximation. Based on the k.p method, we are able to calculate the electronic band structures for the wurtzite InGaN and InGaSb. compounds used in lasers. The effect of strain is analysed because it palys here an important role. we also found that the energy levels, and the optical matrix elements, change with orientation. The optical matrix elements are involved in optical gain calculations, so the growth orientation supply a tool, to control gain in semiconductor laser.
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Barrio Sarriena s/n, UPV/EHU Science Park, Martina Casiano Bld. 3rd floor, 48940 Leioa, Spain+34 648603845
Energy Technology Department, Casaccia Research Centre, Via Anguillarese 301, 00123 Rome, Italy+39 0630486234
Commissariat à l’énergie atomique et aux énergies alternatives - Institut List , CEA Saclay Nano-INNOV, Bât. 861-PC1043 - F-91191 Gif-sur-Yvette cedex, France+33 1 69 08 23 49