bluuebunny/crossref_metadata_2025 huggingface dataset:
Pt Alloys on Carbon Nanostructures as Electrocatalysts for Direct Methanol Fuel Cell
Authors: Giorgi Leonardo , Giorgi Rossella , Gagliardi Serena , Salernitano Elena , Dikonimos Theodoros , Lisi Nicola , de Riccardis M. Federica , Alvisi Marco
Published: October 2010

Extensive efforts are focused on the development of Direct Methanol Fuel Cells, due to
the intrinsic advantages of this type of devices for mobile power supply system. One of the major
drawback of the DMFC resides in the easy poisoning of the anode electrocatalyst (platinum) by COlike
reaction intermediates, which implies the need of high platinum load in order to obtain
reasonable performances. The development of platinum alloys is considered one of the promising
routes for overcoming this problem: the second metal in fact acts as inhibitor of the Pt poisoning. In
this work we have combined the use of unconventional methods to deposit the electrocatalyst
nanoparticles with unconventional carbon supports. PtAu alloys have been deposited by sputter
deposition process on carbon nanofibers with platelet morphology grown by plasma enhanced
chemical vapour deposition on carbon paper. Cyclic voltammetry in H2SO4 was used to determine
the electrochemical active surface and the electrocatalytic performance for methanol oxidation
reaction. Even at lower Pt load, respect to the ones prepared with commercial catalysts supported on
carbon black, the innovative electrodes showed higher performance and stability.
Energy Conservation and Management Strategies for Commercial Li-Ion Batteries in Telecommunication Applications
Authors: Tsujikawa Tomonobu , Yabuta K. , Matsushita T. , Arakawa M. , Hayashi K.
Published: October 2010

In addition to cost and lifetime, important factors in using lithium-ion (Li-ion) batteries as a backup power supply in telecommunication applications are safety and the flatness of discharge voltage to maintain compatibility with existing systems based on lead storage batteries. We have been researching Li-ion batteries using manganese spinel as cathode material from the viewpoints of flat discharge voltage and thermal stability in the event of overcharging or internal short-circuits. The safety of the Li-ion battery was improved by adding a phosphazene flame retardant to the electrolytic solution and cathode of the battery. Then, with the aim of extending battery lifetime, some of the manganese in the cathode was replaced by another metallic element, which showed favorable results.
A Chemical Bonding Approach to Ionic Conduction and Thermal Expansion in Oxide Ion Conductors
Authors: Taniguchi Sachi , Aniya Masaru
Published: October 2010

In complex perovskite-type oxides which have been studied as cathode materials, the thermal expansion coefficient increases with the increase in the oxygen ionic conductivity. In the present study, with the aim to explain such a behavior, a research has been carried out from a chemical bond point of view. For oxides A1-xA′xB1-yB′yO with perovskite structure, the ionicity of the individual bond, A-O and B-O, and the thermal expansion coefficient of mixed compounds were estimated by using semiempirical methods. It has been shown that the thermal expansion coefficient and the oxygen ionic conductivity decrease with the increase in the difference of the ionicity between A-O and B-O bonds. It is also found that the tolerance factor and the specific free volume are linearly correlated with the difference of ionicity.
Synthesis and Properties of Reaction-Bonded SiC Ceramic with Embedded UO2 - TRISO Coated Particles
Authors: Bukaemskiy Andrey , Fachinger Johannes , Bosbach Dirk
Published: October 2010

Ceramics based on SiC are characterized by extreme hardness, high thermal conductivity, relatively low thermal expansion and chemical durability. In principle, SiC ceramics can be considered as a long-term stable matrix for final disposal of radioactive waste, such as coated fuel particles (CP) separated from the graphite matrix from spent HTR (high-temperature gas-cooled reactor) fuel pebbles. In the present work, SiC-based ceramic with the embedded UO2 - TRISO (tristructural-isotropic) coated particles was synthesized by the reaction-bonding process. The synthesis was performed in standard SiC crucible. Several physico-mechanical properties of the synthesized samples were investigated. It was shown that the coated particles in the reaction-bonded silicon carbide (RBSiC) matrix are distributed homogeneously. The amount of pores is insignificant and the crippling of the coated particles is not observed. Besides, the junction between CP and RBSiC matrix and between RBSiC matrix and the SiC crucible is very good. For all ceramic components of the synthesized samples, namely, for the UO2-kernels, SiC-layers, SiC crucible wall and for the synthesized RBSiC ceramics, the values of microhardness and fracture toughness were measured and compared with the reference data. The strength properties, such as tensile strength of the synthesized samples, failure mechanism of the reaction-bonded SiC ceramic with embedded UO2 - TRISO coated particles, microstructure of the fracture surfaces, the peculiarities of the coated particles fracture were investigated in detail. Moreover, the diffusion of radioactive tracers (137Cs, 241Am, 36Cl, 3H) across synthesized ceramic was studied and the high safety characteristics of the synthesized ceramic were demonstrated.
An Innovative Hybrid Process Involving Plasma in a Cold Crucible Melter Devoted to the Futur Intermediate Level Waste Treatment: The SHIVA Technology
Authors: Lemont Florent , Charvin Patrice , Russello Aldo , Poizot Karine
Published: October 2010

The cold crucible technology first developed for the treatment of the high level fission products can also be used for the direct treatment of intermediate level wastes. In this case, the wastes can be under the states of liquids or solids.
The first experiments carried out for the direct treatment of ionic exchange resins emphasised the requirement of very high temperature on the surface of the glass. When this surface is to cold, the unperfected oxidation lead to a glass containing inclusion such as metallic compounds coming from the reduction of species contained in the waste. Thus, the quality of the glass could be not enough to meet with some specific requirements for long term storage.
For few years, the Laboratory of the Innovative Processes has been studied the capability of a cold crucible to involved plasma torches ensuring the high temperature required for a complete oxidation of a large composition of waste. The developments and the assessment of different technological ways lead to build a cold crucible fitted with a bottom inductor together with twin plasma torches above the glass bath. This is the SHIVA process.
The researches carried out on this innovative technology have shown the high efficiency of the combination for the treatment of a large variety of solid wastes. The oxidation is complete and the produced glass can be easily poured in a canister.
This innovative process provides new perspective of treatment for a large variety of intermediate level waste stored on the ground of nuclear facilities.
Cold Crucible Inductive Melting Technology – Application to Vitrification and Ceramization of High Level and Actinide Wastes
Authors: Stefanovsky Sergey V. , Lebedev Vladimir V. , Ptashkin Alexander G. , Dmitriev Sergey A. , Marra James C.
Published: October 2010

Cold crucible inductive melting is a promising method for production of high-temperature materials. The method is based on direct heating of conductive materials by high-frequency (105-107 Hz) electromagnetic field from an external source. Application of the CCIM to production of vitreous borosilicate and alumino/iron phosphate and ceramic waste forms such as Synroc and its varieties and pyrochlore, murataite and garnet-based ceramics has been successfully demonstrated. Currently a full-scale low level waste vitrification plant based on a 418 mm inner diameter cold crucibles energized from a 1.76MHz/160 kW generators is under operation at SIA Radon. This plant was used for demonstration of feasibility of cold crucible vitrification of Savannah River Site high-iron and high iron/aluminum high level wastes. Numerous ceramic and glass ceramic materials containing high level and actinide waste surrogates such as actinide and actinide/rare earth fractions of high level waste have been successfully produced in the Radon lab- and bench-scale cold crucible based units operated at 5.28 and 1.76 MHz. Large-scale cold crucibles may be applied for vitrification of liquid and solid low and high level wastes whereas small-scale cold crucible may be efficiently used for immobilization of actinide-bearing waste generated from advanced nuclear fuel cycle reprocessing.
SiC/SiC Composites Irradiation Behaviour in Fusion Reactor Environment Conditions
Authors: Chen C.H. , Kai J.J. , Chen F.R. , Katoh Y.
Published: October 2010

We developed a new method to quantify the He atoms in the SiC/SiC Composites Irradiation Behaviour in Fusion Reactor Environment Conditions. We focus on the cavities measurements of the energy shift of the He K-edge of the electron energy loss spectrum. The method is based on mapping the density of He atoms inside the measured bubbles. Combining with the number density and the average diameter of the cavities, we are able to distinguish and estimate the amount of He atoms in the cavities and in the matrix, respectively. We found that small bubbles contain much higher density of He atoms than the larger ones. At irradiation temperature above 1000oC, all the He atoms are trapped inside the bubbles. On the contrary, it is not the case at the lower irradiation temperature.
Experimental Development at a Pilot Plant Scale of a Reduced Activation Ferritic/Martensitic RAFM Steel, Asturfer®
Authors: Morán Ana , Coto Rubén , Belzunce Javier , Artímez Jose Manuel
Published: October 2010

Ferritic/Martensitic steels, with chromium contents ranging between 9 and 12%, were introduced into fusion material programs due to their better creep resistance and excellent thermal and nuclear properties compared to austenitic stainless steels. Reduced activation ferritic/martensitic (RAFM) steels are considered promising candidates for the test blanket modules of the future International Thermonuclear Experimental Reactor (ITER), being EUROFER steel is the EU reference material. It is a 9 % Cr RAFM steel which exhibits a tempered martensitic microstructure and presently allows operation up to 550 ⁰C. This paper shows the work carried out to develop at a pilot plant scale a Reduced Activation Ferritic/Martensitic (RAFM) steel, Asturfer ®, with chemical composition and mechanical properties very close to EUROFER steel. 
Simulation and Modelling the Heterogeneous Effects of the Microstructure MOX Fuels on their Effective Properties in Nominal Pressure Water Reactor Conditions
Authors: Largenton Rodrigue , Blanc Victor , Thevenin Philippe , Baron Daniel
Published: October 2010

The experimental Electron Probe Micro Analysis (EPMA) characterizations on the MOX fuels evidence a heterogeneous microstructure, containing several phases. This heterogeneity must be accounted for in the numerical simulation. The first phase of this work, presented here, concerns exclusively the numerical representation of the MOX microstructure in three dimensions. Three identified steps were realized. The first one consisted in the acquisition and the treatment of two-dimensional experimental pictures thanks to a soft-ware already developed [1]. From the made treatments, the following bi-dimensional data were acquired: the surface fraction of every phase, the various diameters of inclusions within a phase as well as their surfaces fractions. However, within the framework of our study, we wished to represent our heterogeneous microstructure in three dimensions. Except, the data, supplied by this soft-ware, were bi-dimensional. Therefore, the second step of our works deal with the stereological domain. The model of Saltykov [2] was used to go back up the two-dimensional statistical information in three-dimensional. Finally, the last step of our works was to develop a tool able to build a meshed periodic numerical representation of the MOX microstructure. This innovative tool, based on a Random Sequential Absorption technique, represents MOX fuels already irradiated in reactor or any heterogeneous fuels envisaged in the future as well. For example it models two or three phases MOX fuel or any multi-phases fuels as well. Moreover, the sizes of the inclusions can vary within each phase. At the moment, the tool models spherical inclusions but nothing prevents from evolving towards more complex morphologies.
Active Materials Based on Implanted Si for Obtaining Intermediate Band Solar Cells
Authors: Sánchez Kefren , Aguilera Irene , Palacios Pablo , Wahnón Perla
Published: October 2010

First-principles calculations carried out for compounds based on Si implanted with different species, as Ti or chalcogens (S, Se, Te), show them as solid candidates to intermediate band (IB) photovoltaic materials. This DFT study predicts electronic structures, formation energies, relaxed atomic structures, optoelectronic properties, diffusion paths, for supercells containing up to several hundreds of atoms. The knowledge of Si-based devices is a relevant factor to facilitate the creation of an IB solar cell. Crystalline samples with a concentration of Ti several orders of magnitude above the solubility limit have been already grown. Formation energy calculations agree with the experiment in showing mainly interstitial implantation. Calculated electronic structure presents an IB, which is in agreement with electrical measurements and models, and is expected to cause an increase of the absorption coefficient across the solar spectrum. Chalcogen-implanted Si is an efficient IR absorber when implantation is carried out at ultra-high concentrations. Substitutional implantation produces a filled band inside Si band-gap and our calculations predict that plausible co-doping with IIIA atoms (as Al, B) would allow to obtain an IB fulfilling all the needed requirements.
Tandem Dye-Sensitized Solar Cells Consisting of Floating Electrode Supported by Non-Conductive Glass Mesh
Authors: Uzaki Kenshiro , Pandey Shyam S. , Ogomi Yuhei , Hayase Shuzi
Published: October 2010

A tandem dye-sensitized solar cell consisting of two electrodes in one cell is reported. The
tandem cell (Cell TAN GF) has a floating electrode (bottom cell) and a TiO2 electrode prepared on a F
doped SnO2 glass (top cell). The floating electrode is a flexible and self-standing composite film
consisting of a porous titania/dye layer supported by a glass mesh. The Incident Photon to Current
Conversion Efficiency (IPCE) curve for the Cell TAN GF had two peaks corresponding to visible
absorptions of the two dyes. The open circuit voltage (Voc) of the Cell TAN GF (0.82 V) was higher
than that of the corresponding single cell (0.6-0.64 V). These results demonstrated that the Cell TAN
GF has a potential for tandem cells. The Voc of Cell TAN GF was almost the same as that of Cell
TAN (0.88 V) in which the glass mesh was replaced by a conductive stainless steel mesh having a
protective layer, leading to the conclusion that a conductive layer is not necessarily needed.
Thin-Film Silicon Solar Cells Using Back Reflector with Embedded Metal Nanoparticles
Authors: Liang Ren Rong , Santbergen Rudi , Zeman Miro
Published: October 2010

Light trapping in the absorber layer of thin-film solar cells is of great importance for obtaining a high photocurrent. A novel light-trapping technique is based on light scattering by metal nanoparticles through excitation of localized surface plasmons. By evaporation of thin silver layers of different thicknesses followed by thermal annealing, silver nanoparticles with different sizes were formed. We show that the plasmon resonance wavelength can be tuned by changing the embedding medium and the particle size. Furthermore, amorphous silicon solar cells with silver nanoparticles embedded between the absorber layer and the back reflector were fabricated. The effect of different sizes of the particles on the solar cell performance was studied. The performance of the solar cells was characterized by quantum efficiency and current-voltage measurements. Both the external quantum efficiency in the wavelength region of 600 to 800 nm and the current density increase as particle size increases, but remain lower than those of the reference device without particles. These results demonstrate that nanoparticles can enhance light trapping, provided that parasitic absorption in the nanoparticles is minimized. This can be achieved by better control of particle shape and size using improved fabrication techniques.
CPV Modules Based on Lens Panels
Authors: Rumyantsev V.D. , Ashcheulov Yu.V. , Davidyuk N.Yu. , Ionova E.A. , Pokrovskiy P.V. , Sadchikov N.A. , Andreev V.M.
Published: October 2010

A work on development of the high concentration photovoltaic (HCPV) modules with Fresnel lens panels and III-V multijunction cells is presented. A composite structure of the small-aperture area 40x40 (or 60x60) mm2 Fresnel lenses, united in a panel, was realized. A silicate glass sheet (front side of a module) serves as a superstrate for transparent microprisms formed in silicone. Small averaged thickness of the prisms ensures low IR absorption of sunlight in comparison with acrylic Fresnel lenses. Temperature dependences of the optical properties in such a type of the solar concentrators and PV properties of the cells in passive heat dissipation conditions are under consideration.
The solar cells are the triple-junction InGaP/(In)GaAs/Ge cells with designated illumination area 1.7-2.3 mm in diameter.
A HCPV module consists of the 144 (or 64) sub-modules in 12x12 (or 8x8) configuration. Solar cells are protected from environment in different ways: by side walls of a module body, or by a rear glass sheet at integrated sealing the cells in a back-side module panel. Module design includes refractive smooth-surface secondary lenses. The cell strings are glued to the rear glass surface of the module body using lamination process. Proper quality of the solar cells in a multistage module assembling procedure is ensured owing to specially developed contactless test method, based on analyzing the electroluminescent signals at local photoexitation.
For arrangement of the HCPV modules in a solar installation, a number of the solar trackers have been developed and realized for 1-3-5 kWp of the installed power.
Solar-Thermal Energy Conversion and Storage: Conductive Heat Transfer Using Self-Assembled Bulk Graphite
Authors: Sorrell Charles C. , Palmer T.C. , Bowen L.J. , Nakaruk A.
Published: October 2010

Consideration of technologies for the use of concentrated solar power (CSP) leads to the conclusion that there is substantially more energy in the sun’s heat than there is in its light. At present, solar-thermal energy conversion and storage systems using CSP have the shortcomings of the use of high pressures and potential problems with corrosion. In the development of new materials and designs, two of the key issues of consideration are the: (a) thermal properties of the materials and (b) heat transfer within the system. Most current technologies utilise convective heat transfer of liquids but there are none that use conductive heat transfer with solid-state systems.
The present work introduces such a system in the form of highly dense and aligned self-assembled graphite, which can be heated in air, provided the hot face temperature is at a temperature sufficiently low to avoid the onset of oxidation. Modelling of a small domestic-scale system, which has no competition in the marketplace, consisting of: (a) 4 m diameter concentrator, (b) block of graphite weighing ~160 kg, and (c) electricity generation system demonstrates that, in only 90 min and at ≤420°C, sufficient heat can be stored to supply 25% more than is required for a typical 24 h, domestic, electricity usage cycle.
PCM-Graphite Latent Heat Storage Systems for Industrial Process Heat Recovery
Authors: Schmitt Rainer , Öttinger Oswin , Steinmann Wolf Dieter , Johnson Maike
Published: October 2010

Increasing energy prices and shortage of fossil fuels lead to a growing interest in alternative energy sources. In combination with energy storage systems the generation of solar process heat can be provided independent from the weather leading for example to a cost efficient stabilization of power output. For this application latent heat storage units with phase change materials (PCMs) can be designed to store solar process heat within a narrow temperature interval utilizing the high storage density of the different PCMs. This is achieved using the latent heat of melting in the melting / solidification process, or the latent heat of re-crystallization in a solid / solid phase transition. However, this advantage can only be used in technical applications if the heat transfer in the PCM is sufficiently high. As most pure PCMs exhibit a low thermal conductivity (about 1 W/(m•K) or less), methods to improve heat transfer in PCMs have been under investigation for decades.
The heat transfer in a PCM can be increased by addition of highly thermal conductive materials. Due to its superior properties - high thermal conductivity, good processability, and chemical inertness - graphite has distinct advantages for this purpose.
Depending on the requirements of the respective application, various routes to combine PCM and graphite are used. For example, besides the fabrication of PCM/graphite composite materials, the increase of heat exchanger surface by highly thermal conductive graphite plates is a favorable method for large scale applications, in particular. Effective thermal conductivities up to 30 W/(m•K) have been realized. This paper gives an overview of actual and potential applications of PCM/graphite heat storage systems focusing on storage of solar heat for high temperature applications such as process heat generation and solar thermal power plants.
Overview of PCMs for Concentrated Solar Power in the Temperature Range 200 to 350°C
Authors: Bauer Thomas , Laing Doerte , Tamme Rainer
Published: October 2010

Thermal energy storage is an essential advantage of solar thermal power plants. The present paper focuses on latent heat storage using a phase change material (PCM). The paper lists literature and gives the current status of PCM work in the temperature range 200 to 350 °C. The system KNO3-NaNO3 is discussed in detail in terms of their thermo-physical properties in the liquid and solid phase. A comparison of literature data and own measurements for the density, heat capacity, thermal diffusivity and thermal conductivity is presented. Measurement results with the following methods are discussed: helium pycnometer, differential scanning calorimeter (DSC) and laser flash. Missing data of the thermal diffusivity and thermal conductivity are partly supplemented. Consistent thermo-physical properties in the liquid phase are presented.
Optical and Thermal Characterization of Solar Receivers for Parabolic Trough Collectors
Authors: Sanchez Marcelino , Mateu Enric , Perez David , García Pierre , Villuendas Francisco , Heras Carlos , Alonso Rafael
Published: October 2010

Concentrating Solar Power Technology (CSP) is nowadays growing mainly due to the technical and economic success of the first projects and to the stable green pricing or support mechanisms that bridges the initial gap in electricity costs (i.e. feed-in tariffs). Future growth will depend on a successful cost reduction and on a strong effort in R&D to optimize the potential for technical improvement [1]. Testing of new materials, components and systems is still of key importance to drive research and innovation improvements to a commercial stage. Receiver manufacturers are investing in R&D in order to improve performances and reduce costs, while project developers are demanding standards to help them evaluate satisfactorily the risks and the benefits of introducing new developments in commercial power plants. The Solar Thermal Energy Department, of the National Renewable Energy Centre (CENER) and the Applied Optics Department of the Universidad de Zaragoza (UZ) have joined efforts to develop a characterization equipment able to measure as far as possible most of the receiver optical and thermal properties. In this paper the testing facility developed by CENER-UZ is described technically. The methodology for optical and thermal characterization of solar receivers for parabolic trough collectors is explained and the preliminary results are presented and discussed in detail.
High-Temperature Transport Properties of Indium Added Cobalt-Antimonide Based Skutterudites Processed by Current Assisted Short-Term Sintering
Authors: Sesselmann Andreas , Hassdorf Ralf , Zastrow Sebastian , Müller Eckhard
Published: October 2010

For more than a decade, skutterudites such as cobalt antimonides have been widely studied as a promising thermoelectric (TE) material for high-temperature applications. High thermoelectric figure of merit (ZT) in this material system can be achieved by suitable doping or by filling the interstitial voids with guest atoms. One of the best improvements in ZT is reported when indium (In) is used as additive to cobalt-antimonide skutterudites, as has been done in this study. Compaction of the grinded powders was carried out by a current-assisted short-term sintering device, which significantly reduces the process time in comparison to conventional hot pressing. Phase homogeneity of the bulk material has been probed by X-ray powder diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX). TE properties (i.e. electrical conductivity, Seebeck coefficient and thermal conductivity) have been analyzed in the temperature range from 300 K to 700 K. The functional homogeneity of the samples was screened by the Potential & Seebeck Microprobe (PSM). Adapted from these results the effect of indium addition to short-term sintered cobalt-antimonide based skutterudites with absence of impurity phases will be discussed.
Raman Spectroscopy Study on Na2/3Mn1-xFexO2 Oxides
Authors: Sendova-Vassileva Marushka , Stoyanova Radostina , Carlier Dany , Yoncheva Meglena , Zhecheva Ekaterina , Delmas Claude
Published: October 2010

The structural properties of sodium manganates and iron substituted sodium manganates with compositions Na2/3Mn1-xFexO2 (x=0, 1/3 and 2/3) were studied by Raman spectroscopy. The Raman spectroscopy allows distinguishing between layered phases with orthorhombic (Cmcm space group) and hexagonal (P63/mmc space group) distortion. It has been found that the crystal structure and the composition of Na2/3MnO2 display a strong dependence on the history of the thermal treatment. The orthorhombic distorted modification is stabilized at high temperatures (1000 oC). At lower quenching temperature, there is a phase separation into an orthorhombic and a hexagonal modification, concomitant with an increase in the oxidation state of Mn. When Fe substitutes for Mn, the hexagonal modification is stabilized. In order to understand the origin of the Raman spectra of Na2/3Mn1-xFexO2, we have used Na2/3Co2/3Mn1/3O2 as a standard for hexagonal structure, where Co3+ and Mn4+ are statistically distributed in the transition metal layers.
Improved Thermoelectrics Based on Bismuth and Antimony Chalcogenides for Temperatures below 240 K
Authors: Lukyanova Lidia N. , Kutasov Vsevolod A. , Konstantinov Piotr P. , Popov Valeri V.
Published: October 2010

Thermoelectric and galvanomagnetic properties for solid solution based on bismuth and antimony chalcogenides were studied for the optimal compositions and carrier concentrations in the temperature interval 100-240 K. Galvanomagnetic properties were analyzed in the framework of the many–valley energy spectrum model with isotropic and anisotropic scattering of charge carries. The figure-of-merit is shown to be determined with optimal relations between the values of the density-of-states effective mass, the carrier mobility taking into account degeneration of charge carriers, and the lattice thermal conductivity. The figure-of-merit also depends on anisotropy of the constant energy surface and scattering mechanism. Average values of the figure-of-merit  through the temperature interval 100-240 K are equal to (2.5-2.65) 10-3 K1 for optimal compositions and carrier concentrations.
Thermoelectric Application for Power Generation in Japan
Authors: Kajikawa Takenobu
Published: October 2010

Thermoelectric power generation technology has been recognized to contribute to the realization of environment-friendly society all over the world in the future. Present status and future prospects on the thermoelectric power generation technology in Japan are overviewed. The thermoelectric applications for power generation have been mainly considered to be one of the waste heat recovery systems from industrial, private, and transportation sectors in the Japanese energy system. Such activities have been in progress in Japan. Then, several demonstration system tests and feasibility study have been achieved using practical heat sources such as industrial furnaces, motorcycles, solid waste incinerators, and solar thermal systems have been achieved mainly by private companies. Several topics of experimental results on advanced modules based on layered oxides, Heusler alloys, filled Skutterudites for power generation from the view points from environment-friendly and nanostrucuture approach are included. In the future prospects the recent R&D projects of advanced materials for thermoelectric power generation technology and the commercialization of thermoelectric power generation applications are discussed.
Theoretical Performance Characteristics of Wearable Thermoelectric Generators
Authors: Leonov Vladimir
Published: October 2010

The theory of thermal matching of a thermoelectric generator with the environment has been applied in this work to a wearable thermoelectric generator. This enabled evaluation of its top performance characteristics in typical environmental conditions. To correctly perform the modeling, the relevant properties of the human body as a heat generator for a small-size thermoelectric generator have been studied and presented in the paper as well. The results have been practically validated in different wearable thermoelectric generators. In particular, a power over 1 mW per square centimeter of the skin has been practically demonstrated on a walking person at ambient temperature of –2 °C. The comparison with wearable photovoltaic cells shows that in typical situations thermoelectric generators provide at least ten times more power.
Ultrapurification of Silicon for Photovoltaic Applications
Authors: del Cañizo Carlos , del Coso Gonzalo , Luque Antonio
Published: October 2010

The recent explosive growth of Photovoltaics and the relative avidity for silicon of the predominant solar cell technology have resulted in a dramatic change of the polysilicon industry structure. While in the past the polysilicon was manufactured almost exclusively for the semiconductor industry, now more than half of the market is devoted to the solar industry. The different alternative routes to purify silicon for photovoltaic applications are presented in the paper, analysing their advantages and drawbacks. Emphasis is made on the CENTESIL initiative, a new private-public partnership venture promoting a pilot plant that is in an advanced state of construction. The goal is to allow the photovoltaic companies worldwide to count with an independent research centre to help them to establish their own polysilicon plant.
Synthesis, Optical and Electrical Properties of Oligo(phenylenevinylene)s Substituted with Electron-Accepting Sulfonyl Groups
Authors: Schmitt Volker , Glang Stefan , Detert Heiner
Published: October 2010

Oligo(phenylenevinylene)s (OPV) composed of five rings and electron donating or withdrawing sulfonyl substituents on the central and lateral rings have been investigated. Two strategies were used for the syntheses of the C2-symmetrical OPVs both include PO-activated olefinations as central steps. Six flexible side chains guarantee good solubility in toluene or dichloromethane. In solution and in films stabilised by polystyrene (60%), the chromophores are strongly fluorescent, with emissions in the violet-blue domain from solutions and in the green to orange region from solid films. The redox potentials, determined by cyclic voltammetry, and the optical properties are strongly depending on the position of the acceptor groups.
Tailoring Optical Properties of Blue-Gap Poly(p-phenylene Vinylene)s for LEDs Applications
Authors: Dilonardo Elena , Giangregorio Maria M. , Losurdo Maria , Capezzuto Pio , Bruno Giovanni , Cardone Antonio , Martinelli Carmela , Farinola Gianluca M. , Babudri Francesco , Naso Francesco
Published: October 2010

There has been growing interest in developing new semiconducting polymers for applications in optoelectronics (OLEDs) due to their exceptional processability and appealing characteristic of manipulating electronic and optical properties by tuning of molecular structure and self-assembling.
This study is an investigation on the interplay among supermolecular organization and optical properties of thin films of the poly[2-(2-ethylhexyloxy)-5-methoxy]-1, 4-phenylenedifluorovinylene (MEH-PPDFV) conjugated polymer, which has fluorinated vinylene units. This interplay is elucidated exploiting atomic force microscopy, spectroscopy ellipsometry, photoluminescence and electroluminescence. Thin films of MEH-PPDFV have been deposited by drop casting on indium-tin-oxide (ITO), quartz and glass substrates. The dependence of polymer chains self-organization and morphology on substrate surface is presented. Furthermore, it is demonstrated that the presence of F-atoms in the vinylene units of the MEH-PPDFV yields a blue optical band gap with the maximum of the fundamental HOMO-LUMO transition at 331 nm and photoluminescence at 458 nm. The OLED built with the above polymer shows a very stable blue-greenish electroluminescence that is also achieved at 504 nm.
Advanced Real Time Metrology of AlGaN/GaN and InGaN/GaN Epitaxy
Authors: Kim Tong Ho , Choi Soo Jeong , Brown April S. , Losurdo Maria , Bianco Giuseppe Valerio , Giangregorio Maria M. , Bruno Giovanni
Published: October 2010

Nitride materials are critical for a range of applications, including UV-visible light emitting diodes (LEDs). Advancing the performance, reliability and synthesis of AlGaN/GaN and InGaN/GaN heterojunction devices requires a systematic methodology enabling characterization of key metric like alloy composition, thickness and quality possibly in real time.
This contribution reports on the real time characterization of the plasma assisted molecular beam epitaxy of AlGaN/GaN and InGaN/GaN heterostructures. Spectroscopic ellipsometry real time monitoring has revealed a number of key process and material iusses, such as the roughening of the GaN templates depending on plasma exposure during the substrate cleaning step, the composition of the alloy and the growth mode. Parameters like the plasma conditions, the surface temperature and the atomic flow ratio are investigated to understand the interplay process-material composition-structure-optical properties.
Terahertz Spectroscopy of Superconductors
Authors: Lupi Stefano , Baldassarre Leonetta , Calvani Paolo , Dore Paolo , Mirri Chiara , Ortolani Michele , Perucchi Andrea
Published: October 2010

We show how synchrotron radiation (SR) in the terahertz (THz) region provides the possibility to measure the properties of conventional and exotic superconductors in their superconducting state. Indeed, through the coupling of SR and a conventional Michelson interferometer, one can obtain in the THz range a signal-to-noise ratio up to 103. We review the application of this technique to superconductors with a different degree of complexity: the single-gap boron-doped diamond BCS isotropic material; CaAlSi, a superconductor isostructural to MgB2 with a slight anisotropy between the gap in the hexagonal planes and that along the orthogonal c axis; and isotropic V3Si, where superconductivity opens two gaps at the Fermi energy.
Stabilization of Superconductivity in Pure and C-Intercalated 1T-TaS2 Synthesised Under High Pressure
Authors: Sellam Amine , Giglioli E. , Rousse G. , Klein Y. , Porcher F. , Le Godec Y. , Mezouar M. , D'Astuto M. , Taverna D. , Loupias G. , Shukla A. , Gauzzi Andrea
Published: October 2010

In order to elucidate the origin of the interplay between charge density wave (CDW) and superconductivity in 1T-TaS2, we have synthesized powder samples of pure and C-intercalated 1T-CxTaS2 by means of a multi-anvil high-pressure synthesis method. We have found that single-phase samples are obtained in the 2-6 GPa range at 400 °C and for x=0-0.3. The structural, magnetic and transport properties of all samples have been investigated by means of neutron and x-ray diffraction, dc magnetization and dc electrical resistivity. For all x values including x=0, the data show that the CDW phase is suppressed concomitant to an abrupt onset of superconductivity, with Tc=3.2 K for x=0. The Tc value turns out to be weakly dependent on x, with a maximum Tc=3.8 K for x=0.2. This onset is accompanied by a crossover of magnetic behavior from paramagnetic Pauli-like to paramagnetic Curie-Weiss-like with effective moment  1.2 B/Ta, which suggests that a ionic picture is suitable for the superconducting phase, but not for the CDW phase. The analysis of the dependence of the a and c lattice parameters upon x as well as upon the synthesis conditions shows that the onset of superconductivity is mainly ascribed to unusual changes of the unit cell induced by the high-pressure synthesis. Specifically, the ex-situ lattice parameters exhibit a significantly larger c-axis parameter and a shrinking of the a-axis parameter stabilized by the high-pressure synthesis route. We argue that the above suppression of the CDW phase is induced by a broadening of the relevant 5d(t2g) band which stabilizes the metallic and superconducting phases. This scenario suggests that the strength of the electronic correlations are the main control parameter of the CDW-superconductivity competition in 1T-TaS2.
Grain Morphology for Bi2Sr2CaCu2O8 Tapes Heat-Treated in High Magnetic Fields
Authors: Watanabe K. , Inoue T. , Awaji S.
Published: October 2010

We prepared Ag-sheathed Bi2Sr2CaCu2O8 (Bi2212) tapes heat-treated in high fields (in-field heat-treatment Bi2212) and heat-treated without magnetic fields (out-of-field heat-treatment Bi2212), in order to examine the magnetic field effect on the microstructure of Bi2212. The differential thermal analysis (DTA) was performed at 10 T using Bi2212 powders. The DTA suggests that the in-field heat-treatment changes the grain morphology of Bi2212. It was found that the critical current density Jc for the in-field heat-treatment Bi2212 tape is largely improved at 10 K in fields. In addition, the in-field heat-treatment Bi2212 tape has also a large n-value in the form of E=Ec(J/Jc)n, which is related to the microstructure change.
Processing by Pulsed Laser Deposition and Structural, Morphological and Chemical Characterization of Bi-Pb-Sr-Ca-Cu-O and Bi-Pb-Sb-Sr-Ca-Cu-O Thin Films
Authors: Ríos Victor , Díaz-Valdés Elvia , Aguilar Jorge Ricardo , Kryshtab T.G. , Falcony Ciro
Published: October 2010

Bi-Pb-Sr-Ca-Cu-O (BPSCCO) and Bi-Pb-Sb-Sr-Ca-Cu-O (BPSSCCO) thin films were grown on MgO single crystal substrates by pulsed laser deposition. The deposition was carried out at room temperature during 90 minutes. A Nd:YAG excimer laser ( = 355 nm) with a 2 J/pulse energy density operated at 30 Hz was used. The distance between the target and substrate was kept constant at 4,5 cm. Nominal composition of the targets was Bi1,6Pb0,4Sr2Ca2Cu3O and Bi1,6Pb0,4Sb0,1Sr2Ca2Cu3OSuperconducting targets were prepared following a state solid reaction. As-grown films were annealed at different conditions. As-grown and annealed films were characterized by XRD, FTIR, and SEM. The films were prepared applying an experimental design. The relationship among deposition parameters and their effect on the formation of superconducting Bi-system crystalline phases was studied.
Microwave Metamaterials Containing Magnetically Soft Microwires
Authors: Ipatov Mihail , Zhukova V. , Zhukov Arcady P. , Panina Larissa V.
Published: October 2010

In this paper we discuss the development of metamaterials containing ferromagnetic microwires which makes it possible to tune the electromagnetic response in the microwave frequency band. Metallic wire media are known to demonstrate very strong dispersion of the effective permittivity at GHz frequencies. At certain conditions, the magnetic properties of constituent wires may strongly contribute to the system losses owing to the magnetoimpedance effect, resulting in unusual dependence of the permittivity on the external magnetic or mechanical stimuli. We also demonstrate the possibility to design the wire media with a negative index of refraction utilizing natural magnetic properties of wires. The results involve theoretical modeling and measurements of the reflection/transmission spectra by free-space methods. A reasonable agreement between theoretical and experimental data is demonstrated.
Full Optical Scatter Analysis for Novel Photonic and Infrared Metamaterials
Authors: Fitzgerald Thomas M. , Marciniak Michael A.
Published: October 2010

Artificial structures with sub-optical wavelength features are engineered to feature non-conventional values for material properties such as optical and infrared permeability and permittivity. Such artificial structures are referred to as optical and infrared metamaterials.[1] The application space of electromagnetic metamaterials includes novel sub-wavelength waveguides and antennas, true time delay devices, optical filters, and plasmonic electronic-optical interfaces.[2]
In this paper presents an optical diagnostic technique adapted for measuring and analyzing bidirectional polarimetric scatter from novel photonic and infrared metamaterials of interest. This optical diagnostic technique is also broadly applicable to other optical/infrared metamaterial structures that are proposed or developed in the future.
The specific project goals are
a) Demonstrate a novel metamaterial characterization full-polarimetric diffuse ellipsometry technique suitable to measure desired material properties with stated uncertainty limits for novel photonic and infrared metamaterials of interest.
b) Demonstrate incorporation of predictive computational codes that estimate the electro-magnetic property values for metamaterial designs and concepts of interest.
Selected Applications of Transformation Electromagnetics
Authors: Gallina Ilaria , Castaldi Giuseppe , Galdi Vincenzo , Alù Andrea , Engheta Nader
Published: October 2010

In this paper, we present a concise summary of selected results from our recent and ongoing studies on transformation electromagnetics. Specifically, we focus on cloak/anti-cloak interactions (with possible application to sensor invisibility), and on some general classes of metamaterial slabs (made of double positive, double negative or single negative media) with interesting image displacing/reconstruction capabilities.
Analysis on Resistive Switching of Resistive Random Access Memory Using Visualization Technique of Data Storage Area with Secondary Electron Image
Authors: Kinoshita Kentaro , Makino Tatsuya , Yoda Takatoshi , Dobashi Kazufumi , Kishida Satoru
Published: October 2010

Both a low and a high resistance stateｓ which were written by the voltage application in a
local region of NiO/Pt films by using conducting atomic force microscopy (C-AFM) were observed
by using scanning electron microscope (SEM) and electron probe micro analysis (EPMA). The
writing regions are distinguishable as dark areas in a secondary electron image and thus can be
specified without using complicated sample fabrication process to narrow down the writing regions
such as the photolithography technique. In addition, the writing regions were analyzed by using
energy dispersive X-ray spectroscopy (EDS) mapping. No difference between the inside and outside
of the writing regions is observed for all the mapped elements including C and Rh. Here, C and Rh are
the most probable candidates for contamination which affect the secondary electron image. Therefore,
our results suggested that the observed change in the contrast of the secondary electron image is
related to the intrinsic change in the electronic state of the NiO film and a secondary electron yield is
correlated to the physical properties of the film.
High-Performance and High-CRI OLEDs for Lighting and Their Fabrication Processes
Authors: Komoda Takuya , Iwakuma Toshihiro , Yamamoto Minoru , Oka Nobuto , Shigesato Yuzo
Published: October 2010

The improvement of the basic performance makes white OLEDs the promising candidate of the next generation, environmental friendly lighting source. However, for the practical application, additional properties of higher color rendering index (CRI), long lifetime at high luminance, large area uniform light emission, and high reliability for long time operation are required. Furthermore, innovative fabrication processes specialized for OLED lighting are required to reduce the cost by improving the material utilization and productivity. We developed various technologies for OLED lighting in the Japanese governmental project “High-efficiency lighting based on the organic light-emitting mechanism” from 2007. In this project, high CRI, highly efficient and long lifetime white OLEDs were realized by optically designed two-unit structure with a fluorescent deep blue emissive unit and a green / red phosphorescent unit. A reliable encapsulation structure with high heat radiation and moisture-proof characteristics realized a stable emission at high luminance as well as long storage stability. Additionally, thermal diffusivities of organic thin films with sub-hundred nanometer thicknesses were analyzed by a “rear heating/front detection type” nanosecond thermo-reflectance method. High speed wet coating process and vacuum deposition process for very thin layers were developed to improve the accuracy, material utilization and productivity.
Organic Syntheses and Characteristics of Novel Conjugated Polymers for AMOLEDs
Authors: Song Su Hee , Jin Young Eup , Shim Joo Young , Lee Kwang Hee , Suh Hong Suk
Published: October 2010

Conjugated polymers with a stabilized blue emission are of importance for the realization of large flat panel AMOLED displays using polymer light-emitting diodes. Several novel conjugated polymers using newly developed templates for the stabilized EL emission are reported. Poly(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[def]phenanthrene)) (PCPP) is a new class of blue-emitting polymers utilizing a new back-bone. This material emits a efficient blue EL without exhibiting any unwanted peak in the long wavelength region (green region) even after prolonged annealing at an elevated temperature of 150oC in air, or operation of the device. New electroluminescent spiro-PCPPs, poly((2,6-(3',6'-bis(2-ethylhexyloxy)-spiro(4H-cyclopenta[def] phenanthrene-4,9'-[9H]fluorene)))-alt-(2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[def]phenanthrene))) (spiro-PCPP-alt-PCPP) and poly((2,6-(3',6'-bis(2-ethylhexyloxy)-spiro(4H-cyclopenta[def] phenanthrene-4,9'-[9H]fluorene)))-alt-(1,4-phenylene)) (spiro-PCPPP), have been synthesized by the Suzuki polymerization. The PL emission spectra of polymers in THF solution show a same maximum peak at 397 nm. The maximum PL emission spectra of polymers appeared at around 463 and 456 nm in solid state, respectively. The PL spectra in solid thin films show more red-shifted over 60 nm than solution conditions. The blue emissions at 400-409 nm for the π–π* transitions of conjugated polymer backbone are almost completely quenched or decreased.