bluuebunny/crossref_metadata_2025_split huggingface dataset:
785 nm Raman Spectroscopy of CVD Diamond Films
Authors: May Paul William , Smith James A , Rosser Keith N 
Published: April 2011

AbstractRaman spectroscopy is a powerful technique often used to study CVD diamond films, however, very little work has been reported for the Raman study of CVD diamond films using near infrared (785 nm) excitation. Here, we report that when using 785 nm excitation, the Raman spectra from thin polycrystalline diamond films exhibit a multitude of peaks (over 30) ranging from 400-3000 cm−1. These features are too sharp to be photoluminescence, and are a function of film thickness. For films >30 μm thick, freestanding films, and for films grown in diamond substrates the Raman peaks disappear, suggesting that the laser is probing the disordered small-grained interface between the diamond and substrate. Some of the peaks change in relative intensity with time (‘blinking’), and the spectra are very sensitive to position on the substrate – this is reminiscent of the behaviour seen in SERS spectra.
Theoretical Analysis of the Graphitization of a Nanodiamond
Authors: Kwon S. Joon , Park Jae-Gwan 
Published: April 2011

AbstractA theoretical analysis of the nanodiamond graphitization was presented. Thermodynamic analysis of the nanodiamond showed three kinds of phase-diagram; smaller nanodiamond, nanodiamond-graphite, and larger nanodiamond. In the theoretical analysis, the most probable and the maximum volume fractions of graphite in the nanodiamond were 0.76 and 0.84, respectively regardless of the annealing temperature and the initial radius of the nanodiamond. The highest graphitization probability decreased with increasing annealing temperature.
The Origin of Field-induced Electron Emission from N-doped CVD Diamond Characterized by Combined XPS/UPS/FES System
Authors: Yamaguchi Hisato , Kudo Yuki , Masuzawa Tomoaki , Shiraki Yoshifumi , Saito Ichitaro , Kudo Masato , Yamada Takatoshi , Takakuwa Yuji , Okano Ken 
Published: April 2011

AbstractElectric field of less than 5 V/um is enough to extract electrons from CVD diamond, whereas field of one to two orders of magnitude higher is needed to extract electrons from metal emitter tips. Diamond has various advantages as an electron emitter in addition to the low-threshold voltage, negative electron affinity (NEA), high thermal conductivity, and high chemical stability. The difficulty in clarification of electron emission mechanism is the factor preventing diamond from being used in practical Quite a few numbers of possible mechanisms have been proposed based on conventional emission current-anode voltage (I-V) characteristics, however, difficulty remained in the determination of origin for emitting electrons. In our previous study, we have succeeded in determining the origin for lightly nitrogen (N)-doped CVD diamond by using combined x-ray photoemission spectroscopy / ultraviolet photoemission spectroscopy / field emission spectroscopy (XPS/UPS/FES) system. The origin at 1.47 eV above valence band maximum (VBM) was consistent with donor level for aggregated N. The origin was at VBM for natural IIb diamond measured as a reference, indicating the emitted electrons strongly depend on the dopant In this study, the origin of emitting electrons for heavily N-doped CVD diamond was characterized by the means of combined XPS/UPS/FES. Extremely low-threshold electron emission at 0.5 V/um is still one of the lowest threshold voltages. Such a low-threshold emission may be possible if electrons are somehow injected to conduction band of diamond and emitted into vacuum through NEA surface. Hence, we strongly believe the determination of the origin for heavily N-doped CVD diamond leads to the clarification of mechanism for low-threshold electron emission from diamond. The system in which we have developed for this study consists of ultraviolet source built in an X-ray photoelectron spectrometer. The diamond sample could be negatively biased up to 4kV relative to the mesh grid for FES. Individual spectroscopy of XPS was performed prior to the combined spectroscopy to determine any possible contaminants on CVD diamond. Peaks referred to C1s and O1s of diamond were observed in addition to Gold, used in a mesh grid set above the sample. Combined spectroscopy of UPS/FES was then, conducted on the CVD diamond to identify the origin of field emitted electrons. The diamond was first illuminated by He I excitation for photoemission. NEA with the typical spectra shape for diamond was observed. After confirming stable operation of individual UPS, negative voltage was applied simultaneously for field emission. Exceeding threshold voltage, a sharp peak, which can be referred to field-emitted electrons appeared in addition to typical UPS spectra. The origin of emitting electrons as well as its dependence on the applied voltage will be discussed.
Barrier Height Difference Induced by Surface Terminations for Field Emission from P-doped Diamond
Authors: Kudo Yuki , Yamada Takatoshi , Yamaguchi Hisato , Masuzawa Tomoaki , Saito Ichitaro , Shikata Shin-ichi , Nebel Christoph E. , Okano Ken 
Published: April 2011

AbstractIn this paper, we measured the field emission properties of reconstructed P-doped diamond under various anode-diamond distances and compared with the oxidized surface. Voltage drops in the vacuum was estimated to be 4.95 and 26.6 V/μm for the reconstructed and the oxidized, respectively. Moreover, we calculated the barrier height ratio between each surface. Our data indicates the changes in electron affinity strongly affect on the field emission properties.
Phosphorous Doping of Microcrystalline CVD Diamond Using Modified Conditions
Authors: Haenen Ken , Lazea Andrada , Mortet Vincent , D'Haen Jan , Geithner Peter , Ristein Jürgen 
Published: April 2011

AbstractPhosphorous-doping of predominantly (110) oriented polycrystalline CVD diamond films is presented. Incorporation of phosphorous into the diamond grains was accomplished by using novel microwave plasma enhanced chemical vapor deposition (MW PE CVD) growth conditions. The substitutional nature of the phosphorous atom was confirmed by applying the quasi-steady-state photocurrent technique (PC) and cathodoluminescence (CL) measurements at low temperature. Topographical information and the relation between substrate and P-doped film grain orientation was obtained with scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD). The optimized growth parameters for P-doped layers on (110) oriented polycrystalline diamond differ substantially from the standard conditions reported in literature for P-doping of single crystalline (111) and (100) oriented diamond surfaces.
Life Cycle Assessment of Photovoltaics; Update of the ecoinvent Database
Authors: Jungbluth Niels , Dones Roberto , Frischknecht Rolf 
Published: April 2011

AbstractRecently, the data for photovoltaics in the ecoinvent database have been updated on behalf of the European Photovoltaics Industry Association and the Swiss Federal Authority for Energy. Data have been collected in this project directly from manufacturers and were provided by other research projects. LCA studies from different authors are considered for the assessment. The information is used to elaborate a life cycle inventory from cradle to grave for the PV electricity production in 3kWp plants in the year 2005.The inventories cover mono- and polycrystalline cells, amorphous and ribbon-silicon, CdTe and CIS thin film cells. Environmental impacts due to the infrastructure for all production stages and the effluents from wafer production are also considered. The ecoinvent database is used as background database.Results from the LCA study are presented, comparing different types of cells and analysing also the electricity production in a range of different countries. It is also discussed how the environmental impacts of photovoltaics have been reduced over the last 15 years, using the CED indicator. The consistent and coherent LCI datasets for basic processes make it easier to perform LCA studies, and increase the credibility and acceptance of the life cycle results. The content of the PV LCI datasets is made publicly available via the website www.ecoinvent.org for ecoinvent members.
Comparative Life-cycle Analysis of Photovoltaics Based on Nano-materials: A Proposed Framework
Authors: Kim Hyung Chul , Fthenakis V. , Gualtero S. , van der Meulen R. , Kim H. C. 
Published: April 2011

AbstractLife cycle analysis becomes especially important for characterizing new material forms in new energy generation technologies intended to replace or improve the current infrastructure of energy production. We propose a comparative life-cycle analysis framework for investigating the effect of introducing nanotechnology in the life cycle of new photovoltaics, which focuses on the differences between the new technologies and the ones that they may replace. The following parameters are investigated within this framework: methods of synthesizing nanoparticles, physicochemical specifications of the precursors, material utilization rates, deposition rates, energy-conversion efficiencies, and lifetime expectancy of the final product. We introduce the application of this framework in comparing nano-structured cadmium telluride and silicon films with their nano- and amorphous- structured equivalents.
A Novel High Capacity, Environmental Benign Energy Storage System: Super-iron Boride Battery
Authors: Yu Xingwen , Licht Stuart 
Published: April 2011

AbstractHigh electrochemical capacity of alkaline boride anodes is presented. The alkaline anodes based on transition metal borides can deliver exceptionally high discharge capacity. Over 3800 mAh/g discharge capacity is obtained for the commercial available vanadium diboride (VB2), much higher than the theoretical capacity of commonly used zinc metal (820 mAh/g) alkaline anode. Coupling with the super-iron cathodes, the novel Fe6+/B2- battery chemistry generates a matched electrochemical potential to the pervasive, conventional MnO2-Zn battery, but sustains a much higher electrochemical capacity.
Wise Energy Investment Decisions–Not Just [kJ out/kJ in]
Authors: Laurin Lise 
Published: April 2011

AbstractWhile the best energy solutions may seem obvious to the LCA community, we often see wind turbines voted down for aesthetics and policy makers leaning toward solutions that show poor return, kilojoule per kilojoule. If we are to move forward with wise energy solutions, we will need to broaden our perspective to include the social impacts that influence policy-makers and communities, creating a decision-system that encompasses both social and environmental impacts.Starting with LCA and Total Cost Assessment, a case study of a biodiesel facility in Vermont begins to incorporate social goals with reduced environmental impacts. We'll then look at other energy systems and how these decision-making tools might be used to bring policy makers, environmentalists, and communities together making wise energy choices for our future.
METAL HYDRIDE ALLOYS FOR ELECTROCHEMICAL ENERGY SOURCE APPLICATIONS
Authors: Bliznakov Stoyan Todorov , Dimitrov Nikolay G , Spassov Tony , Popov Alexander 
Published: April 2011

AbstractHigh-capacity conventional and advanced multicomponent metal hydride alloys were synthesized in this work by two different methods. A set of AB5–type intermetallic compounds, with different Al content, were produced by high-frequency vacuum induction melting method, while AB, A2B and mixed (AB5+Mg)-types composite nanocrystalline-amorphous alloys were obtained mechanochemically by high-energy ball milling in a planetary type mill. The alloys were characterized physically by XRD, SEM and thermodynamically by van't Hoff's plots derived from experimentally obtained PCT isotherms at various temperatures. Different optimized techniques for model electrode preparation from selected metal hydride alloys were also applied. The electrodes were charged-discharged electrochemically in concentrated alkaline solution. In this paper we compare the values for the electrochemical maximum capacity and cycle-life performance of the electrodes prepared by the investigated types of alloys.
Effect of Thermal Treatments on the Transduction Behaviors of Conductometric Hydrogen Gas Sensors Integrated with HCl-Doped Polyaniline Nanofibers
Authors: Wang Pen-Cheng , Dan Yaping , Somers Luke A. , MacDiarmid Alan G. , Johnson A.T. Charlie 
Published: April 2011

AbstractWe present the effect of thermal treatments on the transduction behaviors of HCl-doped polyaniline (PANI) nanofibers integrated in conductometric devices upon exposure to 1% H2 (carried by N2). After drying in N2 at 25ºC for 12 hours, devices showed a ∼10% decrease in electrical resistance upon exposure to 1% H2. However, devices subject to 12-hour drying in N2 at 25ºC followed by further thermal treatments in N2 at 100ºC, 164ºC or 200ºC for 30 minutes showed different transduction behaviors. Specifically, devices subject to thermal treatments at 100ºC and 164ºC showed a decrease in electrical resistance by ∼7% and <0.5%, respectively. More interestingly, the device subject to thermal treatment at 200ºC showed a transduction behavior with opposite polarity, i.e. a ∼5% increase in electrical resistance upon exposure to 1% H2. SEM, FTIR and TGA were employed to investigate the effect of thermal treatments on the morphology and chemical characteristics of HCl-doped polyaniline nanofibers. The results indicated that the change in the devices' interesting transduction behaviors might be related to the thermal treatment effects on the HCl-doped PANI nanofibers in (i) removal of adsorbed water, and (ii) crosslinking and/or degradation of polymer backbones.
SWNTs Bundle Dispersion Study and Analysis of its Potential as a Hydrogen Tank
Authors: Tange Kyoichi , Hirose Katsuhiko , Noda katsutoshi , Mohtadi Rana , Kojima Yoshitsugu 
Published: April 2011

AbstractHigh pressure physic-sorption hydrogen tank using high purity and high surface area SWNTs is considered to be one of the most promising hydrogen tank systems
From Bytes to Ingots: Expedient Design of Structural Materials for Advanced Nuclear Energy Systems
Authors: Zinkle Steven 
Published: April 2011

AbstractDevelopment of structural materials is historically a long and costly process, particularly for nuclear energy applications due to the long proof testing period to validate the performance of the material in the hostile irradiation environment. Utilization of recently developed materials science tools including computational thermodynamics and multiscale radiation damage computational models in conjunction with rapid science-guided experimental validation (nonirradiation and irradiation environments) may offer the potential for a transformational reduction in the time period to develop and qualify structural materials for advanced nuclear energy systems. Several examples of rapid development of high-performance structural materials will be given, with a focus on austenitic and ferritic/martensitic steels (less than two years from project initiation to commercial production of multi-ton prototypic heats). In many cases, the key for development of improved mechanical properties and superior radiation stability is the presence of a uniform high-density dispersion of highly stable nanoscale particles. This research was sponsored in part by the Office of Fusion Energy Sciences, U.S. Department of Energy under contract DE-AC05-00OR22725 with UT-Battelle, LLC.
Characterization of Point Defect Generation, Migration and Coalescence in Irradiated SiC by Atomistic Simulation
Authors: Farrell David , Bernstein Noam , Liu Wing Kam 
Published: April 2011

AbstractRenewed interest in nuclear power in the United States has prompted investigations into new reactor designs, resulting in a need to gain a greater understanding of the properties of the materials which are proposed for use in next generation nuclear reactors. This presentation will focus on preliminary results of large-scale empirical potential atomistic studies into the generation of point defect clusters in 3C SiC by particle irradiation and the evolution from point defect clusters to ‘voids’ on the atomic scale. Our working definition of ‘void’ will be explained in the context of small length-scale simulations. The determination of interstitial and vacancy diffusivities for the empirical potential employed and its impact on defect coalescence will be discussed. The characterization of initial damage states for given irradiation conditions will be presented and compared to previous work on ceramics and ceramic-composites.
Influence of Phase Stability on Radiation Damage Properties: Plutonium-Gallium Alloys
Authors: Valone Steve , Baskes Michael I. , Uberuaga Blas P. , Martin Richard L. , Kubota Alison , Wolfer Wilhelm G. 
Published: April 2011

AbstractModeling cascade and fission damage evolution of actinide materials of all kinds is essential for understanding their aging characteristics. As an example of how exotic some of the damage evolution behavior can be, plutonium-gallium (Pu-Ga) alloys in the δ-phase (fcc lattices) are explored. Aging emanates from the wide variety of spontaneous decay and fission products that, in the case of the Pu, are such species as helium (He) and uranium, among others, as well as interstitials, and vacancies. To aid in our understanding, the modified embedded atom method (MEAM) formalism is applied to the Pu-Ga-He system. The behavior of defects in the fcc (δ) phase of Pu-based materials is strongly influenced by the metastability of this phase. The influence of this metastability on minimum displacement threshold energy, point defect characteristics and He bubbles is delineated. The roles of short-range ordering and transformations of voids into stacking fault tetrahedra in the aging process are also examined.
Effects of Hydrogen Absorption on the Mechanical Properties of Zr-Nb Alloys
Authors: Nishioka Shunichiro , Ito Masato , Muta Hiroaki , Uno Masayoshi , Yamanaka Shinsuke 
Published: April 2011

AbstractYoung's moduli of hydrogenated Zr-Nb alloys were evaluated by using a multiple elastometer in the temperature range from room temperature to 773 K, based on the cantilever characteristic vibration technique. The decreasing rate of Young's modulus against the temperature was independent on the additive amount of Nb. The Young's modulus for the hydrogen solid solution of Zr-Nb alloys decreased and that those for the alloys with partially precipitated hydride slightly changed with increasing hydrogen content in both of Zr-1.0Nb and Zr-2.5Nb. The decreasing rates with hydrogen content of hydrogen solid solution of Zr-Nb alloys were almost same as that of Zr hydrogen solid solution. This result was considered because all specimens largely consisted of α-zirconium in which the solute hydrogen was found to decrease the Young's modulus.
Thermophysical Properties of PuO2 and AmO2 Solid Solutions Simulated by Molecular Dynamics
Authors: Seetawan Tosawat , Khuangthip Thaweewat , Amornkitbamrung Vittaya , Kurosaki Ken , Adachi Jun , Katayama Masahito , Charoenphakdee Anek , Yamanaka Shinsuke 
Published: April 2011

AbstractPuO2 and AmO2 solid solutions: (Pu, Am)O2 are one of the candidates of fuels in a sub-critical accelerator-driven system (ADS). To understand the fuel performance, the thermophysical properties such as thermal conductivity and heat capacity are quite important. However, it is very hard to experimentally determine the physical properties of plutonium as well as americium compounds due to their handling-difficulties. Molecular dynamics (MD) would be a specific method to describe the physical properties of such materials. In the present study, we have investigated thermophysical properties of PuO2, AmO2, and their solid solutions in the temperature range from 300 to 2,500 K. The lattice parameter, compressibility, heat capacity, linear thermal expansion coefficient, and thermal conductivity were evaluated. A Morse-type potential function added to the Busing-Ida type potential was employed as the potential for interatomic interactions. The calculated lattice parameters of (Pu, Am)O2 obeyed Vegard's law, and the values increased with temperature. The heat capacities of (Pu, Am)O2 were similar in any compositions. The thermal conductivities of (Pu, Am)O2 were lower than those of PuO2 and AmO2, indicating that a point-defect scattering effect of phonons could be realized in the MD calculations.
Indentation study of titanium, zirconium, and hafnium hydrides
Authors: Ito Masato , Nishioka Shunichiro , Muta Hiroaki , Kurosaki Ken , Uno Masayoshi , Yamanaka Shinsuke 
Published: April 2011

AbstractMechanical properties of titanium, zirconium, and hafnium hydrides were evaluated by indentation tests in the present study. Single-phase bulk specimens of titanium, zirconium, and hafnium hydrides with a fluorite type structure were produced using a Sieverts' apparatus. The indentation hardness values of titanium and hafnium hydrides were lower than those of the pure metals and drastically decreased with increasing hydrogen content. The hardness of zirconium hydride was higher than that of pure zirconium and slightly depended on hydrogen content. The hardness of the hydrides decreased with increasing maximum indentation load, which has been referred to as indentation size effect. The dependences of hardness on the indentation depth for the hydrides were found to obey the Nix–Gao model. The indentation size effects for the hydrides were significantly smaller than those for the pure metals.
Synthesis and Thermoelectric Properties of Lead Chalcogenide Nanocomposites
Authors: Martin Joshua , Stefanoski Stevce , Wang Li , Chen Lidong , Nolas George S. 
Published: April 2011

AbstractDoped lead telluride dimensional nanocomposites were prepared by densifying nanocrystals synthesized employing an alkaline aqueous solution-phase reaction. The nanocrystal synthesis procedure resulted in high product yields of over 2 g per batch. These nanocrystals were then subjected to Spark Plasma Sintering (SPS) for densification. Transport properties were evaluated through temperature dependent resistivity, Hall, Seebeck coefficient, and thermal conductivity measurements. The results for these lead telluride nanocomposites were compared to bulk polycrystalline lead tellurides with similar carrier concentrations.
In-situ TEM Study of Bismuth Nanostructures
Authors: Jia Xiaoting , Berube Vincent , Chen Shuo , Poudel Bed , Hyungbin Son , Kong Jing , Shao-Horn Yang , Zhifeng Ren , Chen Gang , Dresselhaus Mildred S 
Published: April 2011

AbstractNanostructured thermoelectric materials have attracted lots of interest in recent years, due to their enhanced performance determined by their thermoelectric dimensionless figure of merit. However, because of equipment limitations, not much work has been done on combining simultaneous transport measurements and structural characterization on individual nanostructured thermoelectric materials. With an integrated TEM-STM system, we studied the structural behavior and electrical properties of bismuth (Bi) nanobelts and nanoparticles. Results showed that clean Bi nanostructures free of oxides can be produced by in-situ high temperature electro-migration and Joule annealing processes occurring within the electron microscope. Preliminary electrical measurements indicate a conductivity of two orders of magnitude lower for Bi nanoparticles than that for bulk Bi. Such in-situ studies are highly advantageous for studying the semimetal-semiconductor transition and how this transition could enhance thermoelectric properties.