bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystal Chemistry of Hydrogen Storage Materials
Authors: Jones Martin Owen , David William I. F. , Johnson Simon R. , Sommariva Marco , Lowton Rebecca L. , Nickels Elizabeth A. , Edwards Peter P. 
Published: April 2011

AbstractWe review here work on two classes of compounds that have been promoted as potential hydrogen storage materials; alkali metal amides and borohydrides, highlighting how their crystal structure and chemical properties may be used to influence the key hydrogen absorption and desorption parameters in these materials.
Nanogravimetric Evaluation of Hydrogen Uptake in Thin Film Materials by A Quartz Crystal Microbalance
Authors: Xu Tao 
Published: April 2011

AbstractTo study the hydrogen storage materials in their thin film format provides a unique approach to investigate many interfacial phenomena associated with current research on hydrogen storage materials. However, the challenge is to establish a reliable method to measure weight change of at least a few tens of nanograms in pressurized hydrogen gas. We demonstrate the application of a quartz crystal microbalance for direct mass-metric evaluation of hydrogen storage materials in the pressure range of 0˜40 bars. The frequency shift of a quartz crystal coated with hydrogen absorbing materials is affected by the hydrogen mass uptake on the crystal, the pressure and the viscosity of the gases, and the crystal surface roughness, of which the roughness contribution has no direct analytical expression. Through a control experiment on the same crystal in helium, the roughness contribution in hydrogen can be derived and the frequency shift due to the hydrogen mass uptake is obtained.
AC Loss Properties in Bi2223 Multifilamentary Tapes with Enhanced Transverse Resistivity by Introducing Oxide Barriers
Authors: Inada Ryoji , Mitsuno Yoshiki , Soguchi Kazuma , Nakamura Yuichi , Oota Akio , Li Chengshan , Zhang Pingxiang 
Published: April 2011

AbstractBi2223 multifilamentary tapes with enhanced transverse resistivity by introducing Ca2CuO3 and SrZrO3 as interfilamentary barriers were prepared and their AC loss properties were examined under AC external magnetic field. To improve the deformation properties of these oxide powders, 20-30wt% Bi2212 powders were mixed with them. The mixed oxide powders were introduced among the twisted Bi2223 filaments by using dip-coating method. AC loss properties under AC parallel or perpendicular field were measured and compared with the results for the tape without barriers. The loss measurements were carried out by changing both the amplitude and the frequency of external field. Based on the experimental results, the effect of barrier introduction on the loss reductions was discussed.
Pseudo-Capacitor Structure for Direct Nuclear Energy Conversion
Authors: Popa-Simil Liviu 
Published: April 2011

AbstractThe advanced space missions need for more power opened the way for advanced nuclear reactors and for alternative power conversion procedures. The most advanced power systems available in space are the fuel cells and nuclear reactors. Both systems manifest low efficiencies for converting the primary energy into electricity and as consequence are requiring high heat dump into space mainly by infrared radiation. The thermo-nuclear power generator also requires a high temperature gas turbine and a mechano-electric generator, finally driving to low conversion efficiencies. The new nano-materials offer the possibility of creating direct energy conversion devices able of achieving high conversion efficiencies up to 99% in the cryogenic versions. The interest for direct conversion of the nuclear energy into electricity appeared in early 1940th, by the invention of the thermo-ionic fission device by Linder. Then a series of patents and scientific papers improved gradually the designs and performances of the devices, up to the actual concepts of beta-voltaic and liquid-electronics. The most intuitive direct conversion device looks mainly like a super mirror- or a heterogeneous super-capacitor. The issues on its operation are related to global conversion efficiencies and the stable operation life-time in high radiation field. There are combinations of nano-structures and actinides assuring both the neutron flux stability, by meeting criticality conditions and the direct conversion or the nuclear energy into electricity. Achieving a high efficiency internal conversion of the nuclear energy into electricity is not enough if it is not completed by a high efficiency power extraction system from the nuclear reactor core into the outside load. The development of the new MEMS devices and micro electronics in the 40 nm technologies provides an excellent background for the production of the electric power harvesting and conversion devices embedded in the fuel. The new nano-structured materials may be produced as radiation energy harvesting tiles that are free of actinides, using them for harvesting the energy of radioactive sources and controlled fusion devices, or may include actinides in their structure achieving critical or sub-critical accelerator driven nuclear reactor assemblies. Another predictable advantage of the nano-structure is the property of self-repairing and self-organizing to compensate the radiation damage and improve the lifetime. Due to direct conversion the power density of the new materials may increase from the actual average of 0.2 kw/cm3 to about 1 kw/mm3 driving to miniaturization of nuclear power sources and reductions of the shield weight. At these dimensions and power densities of few thousands horse power per liter the nuclear power source becomes suitable for mobile applications as powering trains, strategic airplanes, etc. These new developments may drive to the production of high power solid-state compact nuclear battery for space applications, leading to a new development stage.
Materials Research for High Energy Density Electrochemical Capacitor
Authors: Burke Andrew F. 
Published: April 2011

AbstractIn April 2007, the Office of Basic Energy Science, United States Department of Energy organized and conducted a Basic Energy Sciences Workshop for Electrical Energy Storage at which basic research needs for capacitive energy storage were considered in detail. This paper is intended to highlight the materials research findings/needs of the workshop and to relate them to the development of high energy density capacitors that can have an energy density approaching that of lead acid batteries, a power density greater than that of lithium ion batteries, and cycle life approaching that of carbon/carbon double-layer capacitors. Capacitors inherently have long cycle life and high power capability so the key issue is how to increase their energy density with minimum sacrifice of their inherent cycle life and power advantages. This requires the development of electrode charge storage materials with an effective high specific capacitance (F/g) and high electronic conductivity. The most promising electrode materials appear to be optimized activated carbons, graphitic carbons, nanotube carbons, and metal oxides. Cells can be assembled that utilize one of these materials in the one electrode and another of the material in the other electrode. Such hybrid cells can operate at 3-4V using organic electrolytes and potentially can have energy densities of 15-25 Wh/kg. Initial research is also underway on solid-state, high energy density devices utilizing high dielectric materials (K>15000) which would operate at very high cell voltage. If such dielectric materials can be developed, these devices may have energy densities approaching those of lithium batteries.
Quantification of Light Trapping Using a Reciprocity Between Electroluminescent Emission and Photovoltaic Action in a Solar Cell
Authors: Kirchartz Thomas , Helbig Anke , Rau Uwe 
Published: April 2011

AbstractSpatially and spectrally resolved electroluminescence (EL) measurements are powerful methods to characterize solar cells, if the EL is properly interpreted. The task of interpreting the results and modeling the spectral and absolute EL emission is strongly simplified by considering the link between EL and quantum efficiency. Using this connection, we show how to quantify the influence of light trapping on the solar cell absorptance using EL.
Red-shifting the surface plasmon resonance of silver nanoparticles for light trapping in solar cells
Authors: Beck Fiona Jean , Catchpole Kylie 
Published: April 2011

AbstractSurface plasmons in metallic nanoparticle arrays have been shown to increase the absorption of an underlying silicon substrate. This has wide ranging applications, not least in the photovoltaic industry. Incident light excites localised surface plasmons in the silver nanoparticles and is coupled into the silicon in trapped modes. The radiative behaviour of the nanoparticle film is changed by the proximity of a high refractive index surface, causing radiation to be directed into the silicon and providing a light-trapping layer. We investigate a simple and effective method of tuning the surface plasmon resonance frequency, and hence the spectral region at which the absorption enhancement is seen, by varying the underlying dielectric. The particle geometry and distribution are modified by the surface conditions provided by the dielectric layer, and both this and the change in refractive index alter the resonance position. Three common dielectrics used in the photovoltaic industry were investigated as surfaces on which to form arrays of self-assembled silver nanoparticles atmospheric pressure chemical vapour deposited titanium dioxide (APCVD TiO2), low pressure chemical vapour deposited silicon nitride (LPCVD Si3N4) and thermally grown silicon dioxide (SiO2). We show, by optical and electrical measurements, that the red-shifted resonances produced by nanoparticle films on APCVD TiO2, and LPCVD Si3N4 with relatively high refractive indices, correspond to an increase in optical absorption and external quantum efficiency in thin, crystalline solar cells at longer wavelengths.
The Influence of Particle Sizes on the Optical Characteristics of Nanocrystalline TiO2 Films for Dye-Sensitized Solar Cells
Authors: Chen Peter Chao-Yu , Rothenberger Guido , Grätzel Michael 
Published: April 2011

AbstractIncreasing the light harvesting efficiency (LHE) of photovoltaic devices is important for improving the conversion efficiency of solar light into electricity. The optical properties of mesoporous TiO2 films for Dye-Sensitized Solar Cells (DSCs) were investigated by varying the size of the particles (20–150 nm). A four–flux optical model was used to describe the light absorption and scattering within the film. Reflectance and transmittance spectra were recorded by a spectrophotometer equipped with an integrating sphere. The wavelength-dependent absorption coefficient k(λ) and scattering coefficient s(λ) were determined for different films. The absorptance G(λ) (absorbed light flux) for films made of different particle sizes and of varying thicknesses can be calculated from these optical parameters. This study helps in improving the optical design of dye-sensitized solar cells.
Thin Film InN/Anatase Bilayers as a Substitute Dye/Semiconductor Interface for Solar Cells
Authors: Hoy Daniel , Kordesch Martin 
Published: April 2011

AbstractThe electronic properties of an InN/anatse bilayer, proposed as a replacement for the dye/semi-conductor interface in Dye Sensitized Solar Cell[1, 2], are measured. RF sputtered thin films of anatase and InN are used as the “dye” replacement. . Two types of InN film are prepared: polycrystalline samples deposited at high temperature, with an optical band gap of < 1 eV, and as-deposited (at least partially amorphous) samples with an optical band gap >1 eV. Energy Dispersive X-ray fluorescence, X-ray Diffraction, and Raman spectroscopy are used to characterize the samples. The resistance in the dark and under illumination are measured. The samples deposited at high temperature are crystalline and have a sheet resistivity ≈ 4 Ω/⁐, and display no photoconductivity. The partially amorphous samples have sheet resistivity of ≈ 500Ω/⁐. Since both types of InN films, including high quality (based on band gap) polycrystalline InN, do not show increased conductivity with light, we conclude that a solar cell based on an InN/anatase bilayer is not feasible.
Fabrication And Characterization of Thermoelectric Generators From SiGe Thin Films
Authors: Budak S. , Guner S. , Hill T. , Black M. , Judah S. B. , Muntele C. I , ILA D. 
Published: April 2011

AbstractThermoelectric materials are being important due to their application in both thermoelectric power generation and microelectronic cooling. The thermoelectric power generations convert the heat change to electricity. The waste of heat could be useful if the thermoelectric power generation is applied. Effective thermoelectric materials have a low thermal conductivity and a high electrical conductivity. A high thermal conductivity causes too much heat leakage through heat conduction. The performance of the thermoelectric materials and devices is shown by a dimensionless figure of merit, ZT = S2σT/K, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature and K is the thermal conductivity. ZT can be increased by increasing S, increasing σ, or decreasing K. In this study, we prepared thermoelectric generator devices of SiGe at the thickness of 112 nm using the ion beam assisted deposition (IBAD) system. Rutherford Backscattering Spectrometry (RBS) analysis was used for the elemental analysis. The 5 MeV Si ion bombardment was performed using the AAMU Pelletron ion beam accelerator to make quantum clusters in the film to decrease the cross plane thermal conductivity, increase the cross plane Seebeck coefficient and electrical conductivity. To characterize the thermoelectric generator devices before and after Si ion bombardment we measured the cross plane Seebeck coefficient, electrical conductivity by Van der Pauw method, and thermal conductivity by 3w method for different fluences.
Surface Mediated Processes in the Interaction of Spent Fuel or alpha-doped UO2with H2
Authors: Cui Daqing , Ekeroth Ella , Fors Patrik , Spahiu Kastriot 
Published: April 2011

AbstractIn most deep disposal concepts, large amounts of hydrogen are expected to be produced by the anoxic corrosion of massive iron containers. At repository temperatures, hydrogen is quite inert and is not expected to contribute to the redox capacity of the deep groundwaters. In several recent works, a large impact of dissolved hydrogen on the dissolution of the LWR or MOX fuel and UO2(s) doped with233U or238Pu has been observed. For hydrogen concentrations above a certain limit, the dissolution rates of these highly radioactive materials drop to very low values. A discussion of the results obtained with spent fuel or α-doped UO2in the presence of a range of hydrogen concentrations is presented. Typical for all measurements under such conditions are the very low long term concentrations of uranium and other redox-sensitive radionuclides, such as Tc and the minor actinides. The concentrations of U are systematically lower than the values measured during UO2(s) solubility measurements carried out in the presence of strong reducing agents. Measurements of the radiolytic oxygen after long leaching periods result in values below detection limit. The investigation of the surface of spent fuel or UO2(s) pellets doped with233U by XPS after long periods of testing shows absence of oxidation. The kinetics of the release of non-redox sensitive elements such as Sr and Cs, used to estimate fuel matrix dissolution rates, is also discussed. An attempt is made to propose potential mechanisms responsible for the observed behaviour, based mainly on data from studies on the interaction of water adsorbed on the surfaces of metal oxides or actinide oxides with radiation. Another important effect observed in recent studies is the existence of a threshold for the specific alpha activity below which no measurable influence of the alpha radiolysis on the uranium release from UO2is observed. The importance of such a threshold for the behaviour of spent fuel under repository conditions encompassing very long time scales will be discussed, as well as the necessity to better investigate the mechanisms of recombination reactions in a thin water layer on the surface of actinide oxides affected by α-radiolysis.
On the Suitability of Lanthanides as Actinide Analogs
Authors: Raymond Kenneth , Szigethy Geza 
Published: April 2011

AbstractWith the current level of actinide materials used in civilian power generation and the need for safe and efficient methods for the chemical separation of these species from their daughter products and for long-term storage requirements, a detailed understanding of actinide chemistry is of great importance. Due to the unique bonding properties of the f-elements, the lanthanides are commonly used as structural and chemical models for the actinides, but differences in the bonding between these 4f and 5f elements has become a question of immediate applicability to separations technology. This brief overview of actinide coordination chemistry in the Raymond group at UC Berkeley/LBNL examines the validity of using lanthanide analogs as structural models for the actinides, with particular attention paid to single crystal X-ray diffraction structures. Although lanthanides are commonly accepted as reasonable analogs for the actinides, these comparisons suggest the careful study of actinide materials independent of their lanthanide analogs to be of utmost importance to present and future efforts in nuclear industries.
Soft X-ray Studies of Pu Electronic Structure: Past Lessons and Future Directions
Authors: Tobin James G , Yu SW 
Published: April 2011

AbstractPhotoelectron Spectroscopy (PES) [1] and X-ray Absorption Spectroscopy (XAS, Figure 1) [2-4] have contributed greatly to our improved understanding of Pu electronic structure. From these and related measurements, the following has been determined.
The Utilization of Spin Polarized Photoelectron Spectroscopy as a Probe of Electron Correlation with an Ultimate Goal of Pu
Authors: Tobin James G , Yu SW , Chung B W , Morton S A , Komesu T , Waddill G D 
Published: April 2011

AbstractWe are developing the technique of spin-polarized photoelectron spectroscopy as a probe of electron correlation with the ultimate goal of resolving the Pu electronic structure controversy. Over the last several years, we have demonstrated the utility of spin polarized photoelectron spectroscopy for determining the fine details of the electronic structure in complex systems such as those shown below.
Communicating Nanoscale Science and Engineering to the General Public
Authors: Batt Carl 
Published: April 2011

AbstractCommunicating the underlying concepts in nanotechnology to the general public is challenging but essential as its impact on society increases over time. We have created a webzine called Nanooze and a traveling museum exhibition called Too Small to See to help communicate nanoscale science and engineering concepts. Nanooze was launched in 2006 and covers the basic concepts of nanotechnology along with the latest in scientific discoveries and interviews with scientists. Its mission is to excite, educate, and challenge kids age 6 to 10 years old and their teachers. Nanooze covers both the underlying science of nanotechnology and its applications. It has attracted a broad audience and has been one of the core resources to a number of national/international competitions, schools and after-school groups. Surveys of readers reveal that over 50% thought that Nanooze was cool with approximately 21% stating that they visit Nanooze once a month. During the 2006 FIRST Lego League competition, which Nanooze supported, 385,000 hits were recorded in one month indicating its broad reach. Too Small to See is a traveling museum exhibition that immerses visitors in a hands-on interactive experience in nanotechnology. This five thousand square foot exhibition is currently on a national tour after debuting at Epcot, Walt Disney World Resort. Too Small to See takes the visitor from the macroscale world to the nanoscale world through a series of interactive and video experiences using everyday objects as the focal point. Once there, the visitor can play with atoms and take on challenges that illustrate the difficulties of nanotechnology. Summative evaluation has revealed that 60% of the visitors were interested in knowing more about nanotechnology as a result of the exhibits. Over 80% of the visitors surveyed altered their viewpoint of the smallest thing that they could think of from a macroscopic object to a nanoscale object after using the exhibits.
The Properties And Performance Of Micro-Tubular (Less Than 1mm Od) Anode Supported SOFC's For APU-Applications
Authors: Song Jung-Hoon , Roy Brycen , Galloway Kevin , Sammes Nigel , Suzuki Toshio 
Published: April 2011

AbstractMicro tubular solid oxide fuel cells (SOFCs) have many desirable advantages compared to general SOFC. Recently, microtubualr SOFC are now studied to apply into APU system in a future generation vehicles. In this study, electrochemical and mechanical properties of the micro tubular SOFCs (less than 1 mm O.D.) have been characterized. Electrochemical characterization showed the excellent performance of MT SOFC with the power density of 1 W/cm2 at 600°C. Impedance measurement indicated that the contribution of contact resistance on the cell performance was still high and there were many possibilities to improve the cell performance. Mechanical test of the MT-SOFC using burst testing apparatus indicated the mechanical properties were mainly dependent on porosity and wall thickness, i.e. physical properties of anode support. This study examined the properties of micro-tubular SOFC using the novel characterization method for APU application.
Evaluation of Durability of Mortars and Concretes Used in Ancient Structures
Authors: Aloy A. S. , Harbour J.R. , Holtzscheiter E.W. , Langton C.A. 
Published: April 2011

AbstractThe data on historic mortars and concretes provide qualitative and quantitative information to evaluate long-term behavior of cement materials in repositories and to understand processes that may occur in repositories (e.g., interaction with other materials and radionuclide transfer). Beyond that, such information is important to demonstrate safety aspects of the repositories to the public and stakeholders.A number of reports have been devoted to study of historical mortars and concretes used in the Western countries. The purpose of this paper is to review studies on compositions and structures of analogs, located mainly over the former Soviet Union's territory.
What Will We Do With the Low Level Waste From Reactor Decommissioning?
Authors: Meehan Dr Adam R , Wilmott Dr Stephen , Crockett Miss Glenda , Watt Dr Nick R 
Published: April 2011

AbstractThe decommissioning of the UK’s Magnox reactor sites will produce large volumes of low level waste (LLW) arisings. The vast majority of this waste takes the form of concrete, building rubble and redundant plant containing relatively low levels of radioactivity. Magnox Electric Ltd (Magnox) is leading a strategic initiative funded by the Nuclear Decommissioning Authority (NDA) to explore opportunities for the disposal of such waste to suitably engineered facilities that might be located on or adjacent to the site of waste arising, if appropriate and subject to regulatory acceptance and stakeholder views. The strategic issues surrounding this initiative are described along with an update of progress with stakeholder consultations in relation to the proposed licensing of the first such facility at Hinkley Point A, which could be viewed as a test case for the development of similar disposal facilities at other nuclear sites in England and Wales.