bluuebunny/crossref_metadata_2025_split huggingface dataset:
Equilibrium Thermodynamics Near the Glass Transition - The Conceptual Application of the Limiting Fictive Temperature
Authors: Wilde G. , Perepezko J. H. 
Published: April 2011

AbstractThe enthalpy, entropy, specific heat, specific volume and the equilibrium shear viscosity of the deeply undercooled melt of the bulk glass forming alloy Pd40Ni40P20 have been determined as functions of temperature. The concept of limiting fictive temperature was applied to the entire set of measurements in order to allow for a valid comparison of the data based upon the respective equilibrium values. The comparison of the equilibrium properties shows that a proposed hierarchy of stability limits does not apply for this alloy. The results also indicate that the glass temperature as defined by the limiting fictive temperature does not depend on the property under observation.
Oxygen Distribution in Zr-Based Metallic Glasses
Authors: Ping D. H. , Hono K. , Inoue A. 
Published: April 2011

AbstractThis paper reports the atom probe analysis results of the oxygen dissolved in the as-cast amorphous and crystallized Zr65Cu15Al10Pd10 and Zr65Cul17.5Ni10Al17.5 alloys. Impurity oxygen ranging from 0.1 to 1 at.% is dissolved uniformly in the as-quenched Zr65Cu15A110Pd10 and Zr65Cu17.5Ni10Al7.5 amorphous alloys even though the oxygen is not added intentionally. When the Zr65Cu15Al10Pd10 alloy is crystallized, oxygen redistribution occurs; it is rejected from the primary Zr2 (Cu, Pd) crystals and partitioned in the subsequently crystallized phases. Oxygen atoms are enriched in some of the crystalline phases up to approximately 4 at.%, and virtually no oxygen is dissolved in the remaining amorphous phase. In the partially crystallized Zr65Cu17.5Ni10Al7.5 alloy, fine oxygen enriched particles containing ∼ 15 at.%O have been detected in direct contacted with crystalline grains. This work demonstrates that oxygen redistribution occurs during the crystallization reaction, thereby influencing the kinetics of crystallization.
Simulation of Stress Distribution and Mechanical Response of Metallic Glasses
Authors: Kogure Y. , Doyama M. 
Published: April 2011

AbstractMolecular dynamics simulation of the metallic glasses has been done. The embedded atom method potential function for copper is used to express the atomic interaction. The stress distribution in the glassy state is evaluated from specific volume occupied by single atom and local density in divided cells. The displacements of individual atom under the shear stress are calculated and the correlation between the displacements and the atomic volumes are investigated.
Corrosion Resistant Coatings for High Temperature Applications
Authors: Besmann T. M. , Haynes J. A. , Cooley K. M. , Vaubert V. M. , Lee W. Y. 
Published: April 2011

AbstractEfforts to increase efficiency of energy conversion devices have required their operation at ever higher temperatures. This will force the substitution of highertemperature structural ceramics for lower temperature materials, largely metals. Yet, many of these ceramics will require protection from high temperature corrosion caused by combustion gases, atmospheric contaminants, or the operating medium. This paper discusses examples of the initial development of such coatings and materials for potential application in combustion, aluminum smelting, and other harsh environments.
Kinetics of Copper Chemical Vapour Deposition from Cu(hfac)VTMS
Authors: Heerdt M. L. H. Ter , Van Der Put P.J. , Schoonman J. 
Published: April 2011

AbstractA new model, based on irreversible reactions, is used to describe surface kinetics in copper Chemical Vapour Deposition. The mechanism proposed includes a reduction reaction with hydrogen parallel to the well-known disproportionation reaction of Cu(hfac)VTMS. This reduction reaction, not easily modelled by Langmuir-Hinshelwood-type models, appears to be important only at sufficiently high hydrogen partial pressures. The rate constants of the precursor adsorption reaction and the disproportionation reaction are low, probably caused by the dissociation included in these reactions.
Chemical Vapor Deposition (CVD) of Parylene Films using Liquid Source Delivery
Authors: Xu Chongying , Baum Thomas H. 
Published: April 2011

AbstractParylene-N films were formed on silicon substrates at a substrate temperature of −20 °C and pressures from 4 - 7 torr via liquid source precursor delivery. [2.2 ] Paracyclophane, the precursor of parylene-N, was dissolved in an organic solvent and delivered into a vaporizer / pyrolysis unit. The solution was vaporized at ∼ 200 °C and its vapor was cracked at ∼ 700 °C to generate the reactive morromeric species. Films were grown by condensation and polymerization, and analyzed by infrared (FTIR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD) analysis. These analyses indicated the formation of parylene-N films without detectable solvent contamination or incorporation into the polymeric films.
Boron-Doped Diamond Films for Electrochemical Applications
Authors: Martin Heidi B. , Smith Bridget A. , Angus John C. , Landau Uziel , Anderson Alfred B. 
Published: April 2011

AbstractDiamond electrodes possess unique chemical stability, a very wide potential window of water stability, and low background currents. These properties give rise to numerous possible applications, for example, electrosynthesis and electrodestruction reactions at extreme potentials and environmental conditions and as a sensor electrode in aggressive environments. Furthermore, the study of semiconducting diamond electrodes promises to lead to greater understanding of the surface chemistry of diamond and of electronic levels and surface states in doped diamond. In this paper the reactivity of diamond electrodes and their use in a molten salt environment, as a sensor element, and for characterizing diamond are discussed.
Low Stress Under Bump Metallizations for Direct Chip Attach
Authors: Su P. , Korhonen T. M. , Hong S. J. , Korhonen M. A. , Li C. Y. 
Published: April 2011

AbstractIn order to use a flip chip method for bonding the Si chip directly to an organic substrate, compatible under bump metallization (UBM) must be available. Conventional schemes with a copper-based solderable layer are not well compatible with the high-tin solders (such as eutectic Pb-Sn) used with organic substrates. This is due to the rapid reaction between Sn and Cu which depletes the UBM of copper. Ni-based schemes exhibit slower reaction with the solder and have been identified by the semiconductor industry as preferable replacements to Cu-based UBM's. However, Ni-containing metallurgies are often associated with high stresses, which results in poor practical adhesion between the silicon chip and the metallization, leading to interfacial failure during fabrication or service. In this research, several nickel-containing UBM schemes are studied experimentally. Stress measurements are made for each metallization before patterning of UBM pads. An optimal Ni concentration for the UBM is suggested based on the results from this study.
Physical Behavior of Fluorine Atoms in the Fabricated Transparent SiO2 Thin Film at Room Temperature
Authors: lizuka H , Murahara M 
Published: April 2011

AbstractThis paper describe the growth of a transparent SiO2 thin film performed by using Xe2• excimer lamp at room temperature. In this study, NF., and O2 mixture gases was employed as a reaction gas. A silicon substrate was placed in a reaction chamber, which was filled with NF3 and O2 mixture gases. The mixture gases were exposed to the Xe2• excimer lamplight, and SiF4 and NO2 gases were produced by photochemical reaction. Subsequently SiF4 adsorbed onto the Si substrate. SiO2 was formed by oxidation reaction between SiF4 and NO2. These processes occur spontaneously, and SiO2 film is grown. The refractive index of fabrication SiO2 thin film is 1.32. By annealing at 200°C, the refractive index of this filn was increased to 1.44. Further increase in the annealing temperature, resulted in a higher refractive index and lower density of fluorine atoms.
Thickness Effect on Cracking Phenomena and Mechanical Properties of Submicron Glass Thin Films Deposited on a Polymer Substrate
Authors: Yanaka M. , Kato Y. , Tsukahara Y. , Takeda N. 
Published: April 2011

AbstractThe multiple cracking progress in thin SiOx films deposited on polyethylene terephthalate (PET) substrates during tensile tests were investigated. Five kinds of specimens with different SiOx film thicknesses of 43, 67, 90, 120 and 320 nm were prepared. With the appropriate estimation of the residual strain in the film, the crack onset stress was found to be nearly proportional to the minus one-half power of the thickness. After the cracking is sufficiently developed, on the other hand, thinner specimens showed higher crack density than thicker ones. In order to predict the multiple cracking progress, stress distributions in the cracked films were calculated both by the elastic-plastic finite element analysis and modified shear lag analysis. The prediction, under the assumption of the unique stress criterion, explained reasonably well the multiple cracking progress obtained in the experiments.
Nitrogen-Induced Nanocrystallinity of CVD Diamond Films on Ti-6Al-4V Alloys
Authors: Catledge Shane A. , Vohra Yogesh K. 
Published: April 2011

AbstractMicrowave plasma chemical vapor deposition (CVD) was used to grow nanocrystalline diamond films by adding nitrogen to a high density plasma defined by a high operating pressure (125 Torr) and high methane feedgas concentration (15% in a balance of hydrogen). Films grown at these conditions but without nitrogen exhibited well-faceted, high phase purity crystalline diamond while those grown with added nitrogen showed a nanocrystalline structure and were an order of magnitude smoother. The nitrogen-induced nanocrystalline films are believed to be comprised predominantly of diamond nanocrystallites in a matrix of tetrahedral amorphous carbon. The films were characterized by Raman spectroscopy, grazing-angle x-ray diffraction, surface profilometry, nano-indentation, electron microscopy, and pin-on-disc tribometry. In contrast to standard CVD conditions, the high density plasma results in adhered films on Ti-6AI-4V substrates even at substrate temperatures of 850°C. We present plasma optical emission spectroscopy results which are correlated with changes in the Raman spectra and the film microstructure. The hardness of the films (∼90 GPa), their low rms surface roughness (27 nm), and their good adhesion to the substrate makes these films potentially useful for tribological applications.
13C NMR Spectroscopy of Amorphous Hydrogenated Carbon and Amorphous Hydrogenated Boron Carbide
Authors: Braddock-Wilking Janet , Lin Shiu-Han , Feldman Bernard J. 
Published: April 2011

AbstractWe report the 13C NMR spectra of amorphous hydrogenated carbon and boron carbide. The amorphous hydrogenated carbon spectra consist primarily of a sp2 carbon peak at 40 ppm and a sp3 carbon peak at 140 ppm and are in reasonable agreement with recent theoretical calculations of Mauri, Pfrommer, and Louie, but there are some noteable discrepancies. The amorphous hydrogenated boron carbide spectra are very different from that of amorphous hydrogenated carbon, showing two sharp lines at 135 and 170 ppm at low boron concentrations and an intense, broader line at 15 ppm at high boron concentrations. We suggest the two sharp lines at 135 and 170 ppm could be due to carbon atoms in boron-containing aromatic rings, and the broader line at 15 ppm as due to carbon atoms in boron carbide icosahedra. These lines provide evidence of nanocrystalline structure imbedded in an amorphous hydrogenated boron carbide matrix.
Synthesis of Crystalline Structures of CNx, Thin Films Deposited on Sapphire, Quartz and Alumina Substrates
Authors: Alexandrescu R , Cireasa R. , Crunteanu A. , Cojocaru C. S. , Morjan I. , Kumar A. , Vasiliu F. 
Published: April 2011

AbstractCarbon nitride films raise current interest for their potential applications as ultrahard materials. We report on the formation of crystalline CN structures in films deposited at 248 nm on different substrates (sapphire, quartz, alumina) using the laser-induced CVD method and a gas mixture containing ethylene/nitrous oxide and ammonia as carbon and nitrogen source, respectively. The structural and morphological properties of the films were characterized by different analytical techniques (SEM, TEM, TED and XPS).
Novel Uses of Boron Phosphide Films
Authors: Waddell Ewan 
Published: April 2011

AbstractPlasma Assisted Chemical Vapour Deposition (PACVD) deposited films of Boron Phosphide (BP) are known to be very effective in protecting the 8-11.5μm band IR substrate materials germaniurn and zinc sulphide from solid and liquid particle erosion encountered in high speed flight. This paper describes the results obtained by protecting the 3-5μm band substrate material silicon and the 8-11.5μm band substrate material zinc selenide. In addition, results are presented which show that germanium can be very effectively protected from the corrosive effects of salt fog.
Static Dissolution of Uo2 in Interstitial Boom Clay Water
Authors: Lemmens K. , Cachoir C. , Iseghem P. Van 
Published: April 2011

AbstractStatic dissolution experiments were performed with unirradiatcd UO2 in Boom Clay water. The objectives were (1) to measure the solubility of uranium species in Boom Clay water, with UO2 as the solid phase, and (2) to assess the impact of dissolved organic matter and carbonate concentration on this solubility. The tests were supported by calculations with geochemical codes to indicate possibly solubility controlling solid phases. The tests were performed in anoxic and reducing conditions, at 20 and 25°C. The following conclusions could be drawn: (1) Within 2 months in anoxic conditions, the uranium concentrations appear to approach saturation. (2) The “near-saturation” concentrations are between 2.4 and 7.8× 10−7 M. (3) The influence of the carbonate concentration and humic acids on the uranium concentration was apparently small, but the interpretation is hampered by pH and Eh variations. (4) The concentrations tend to be higher than the concentrations found in literature for similar Eh and/or pH conditions; this can probably be explained by small differences in experimental conditions. (5) The measured “near steadystate” uranium concentration in the real clay water agrees relatively well with the solubility calculated for uraninite. (6) Addition of sulfide species reduced the rcdox potential, but not the uranium concentrations, except in real Boom Clay water.
Modeling of Geochemical Compatibility of Near Field Materials in Terms of Radionuclide Retention Properties
Authors: Lucille P. L. , Burnol A , Ollar Ph. 
Published: April 2011

AbstractThe containment of radionuclides over very long periods of time is based on the interposition of a multi-barrier system between the waste and the biosphere. A performance allocation study is usually conducted for each barrier. Each barrier is then designed, in terms of geometry and composition, to cope with the performance it has been allocated. However geochemical interactions will occur between the different barriers. An alkaline plume will be generated by cement materials, a redox front will be generated by container corrosion and geochemical gradients will be generated by the dissolution of artificial barriers by natural groundwater. Radionuclide retention mechanisms are strongly pH and Eh dependent, therefore the impact of these geochemical transients on retention must be quantitatively evaluated to check the performance of each barrier for realistic in-situ situations. To assess this impact, two types of engineered barriers (clay and cement) for a spent fuel repository are simulated with a coupled hydrogeochemical model. Comparisons between hydraulic heterogeneous (fractured) and simple homogeneous systems are also carried out in terms of waste dissolution.
Amorphisation of Perovskite: the Effectofcomposition and Pre-Existing Cation Vacancies
Authors: Smith Katherine L. , Lumpkin Gregory R. , Blackford Mark G. , Vance Eric R. 
Published: April 2011

AbstractEight perovskites of different compositions and pre-existing vacancy contents were irradiated with 1.5 MeV Kr+ ions using the HVEM-Tandem User Facility at Argonne National Laboratory. The critical dose of 1.5 MeV Kr+ ions for amorphisation (Dc) of NaNbO3, SrTiO3 and two natural perovskites varies with composition and may decrease with Na content. The D,c values of 5 members of the solid solution series from SrTiO3 to La0.67TiO3 do not exhibit a simple relationship with vacancy content: In particular, Dc(Sr0 7La0.2TiO3) is extraordinarily high (>170 × 1014 ions cm−2) compared to those of the other (Sr, La)-perovskites in the series, which have Dc values between 2.4 and 11 × 1014 ions cm−2.
A Model for Dissolution of Cao-Sio2-H2O Gel at Ca/Si<1 by Considering Disordered Structure
Authors: Rahman Md. Mazibur , Nagasaki Shinya , Tanaka Satoru 
Published: April 2011

ABSTRACTA model for dissolution of CaO-SiO2-H2O (C-S-H) gel is proposed by considering a Margules type of non-ideal mixture of binary solid solutions at Ca/Si (C/S)<1. The Guggenheim and Prausnitz equations are used to represent the activities of model solids as a function of mole fractions. The Gibbs-Duhem equation, together with the activities of model solids, is applied to express the conditional solubility products of model solids as a function of C/S ratio. The determination of Guggenheim’s empirical parameters is performed with the geochemical code PHREEQE on experimental data. The dissolution model is developed by considering the effect of disorder in the structure of C-S-H gel at C/S<1. The solubility results predicted by the proposed model are comparable with experimental data. The study predicts some structural information of C-S-H gel at C/S<1.
Gallium Removal from Weapons-Grade Plutonium and Cerium Oxide Surrogate by a Thermal Technique
Authors: Park YoungSoo , Kolman David G. , Ziraffe Hisham , Haertling Carol , Butt Darryl P. 
Published: April 2011

AbstractThis paper describes the process of gallium removal from Ga2O3 -doped CeO2−x a surrogate for weapons-grade PuO2−x. Gallium is removed from the surrogate feedstock material using thermal techniques. An Ar-6% H, gas was used in order to reduce the oxide to gaseous Ga2O. Experimental results were shown in the temperature range of 600°C to 1200°C as a function of time and sample geometry. The results to date have shown that CeO2−x is a very good surrogate for PuO2−x.
Colloidal Agglomerates in Tank Sludge and Their Impact on Waste Processing
Authors: Tingey J. M. , Bunker B. C. , Graff G. L. , Keeper K. D. , Lea A. S. , Rector D. R. 
Published: April 2011

AbstractDisposal of millions of gallons of existing radioactive wastes in underground storage tanks is a major remediation activity for the United States Department of Energy. These wastes include a substantial volume of insoluble sludges consisting of submicron colloidal particles. Processing these sludges under the proposed processing conditions presents unique challenges in retrieval transport, separation, and solidification of these waste streams. Depending on processing conditions, these colloidal particles can form agglomerated networks having high viscosities that could clog transfer lines or produce high volumes of low-density sediments that interfere with solid-liquid separations. Under different conditions, these particles can be dispersed to form very fine suspended particles that do not settle. Given the wide range of waste chemistries present at Department of Energy sites, it is impractical to measure the properties of all treatment procedures. Under the current research activities, the underlying principles of colloid chemistry and physics are being studied to predict and eventually control the physical properties of sludge suspensions and sediment layers in tank wastes and other waste processing streams. Proposed tank processing strategies include retrieval transport, and solid-liquid separations in basic (pH 10 to 14), high ionic strength (0.1 to 1.0 M) salt solutions. The effect of salt concentration, ionic strength, and salt composition on the physical properties such as viscosity, agglomerate size, and sedimentation of model suspensions containing mixtures of one or two of the major components found in actual wastes have been measured to understand how agglomeration influences processing. Property models developed from theory and experiment on these simple suspensions are then applied to explain the results obtained on actual wastes.
Alpha-Spectroscopy and Leach Testing of Synroc Doped With Actinide Elements
Authors: Hart K. P. , Vance E. R. , Stanojevic R. , Day R. A. 
Published: April 2011

AbstractSynroc specimens doped individually with ˜ 1 wt% of Np or Pu have been studied, after leaching for >2,500 days, using α-spectroscopy and SEM. In the last leaching period, the leachant was replaced on either a daily or monthly basis. When the leachant was replaced on a daily basis the release rate of Np was similar to that measured when the samples were first leached, whereas for the monthly replacement the release rates of Np or Pu were about a factor of 20 to 30 lower than that for daily replacement. These findings agree generally with the results obtained from surface examination of the samples which showed that the thickness of actinidedepleted surface layer of anatase was 0.3 μm for monthly replacement but only 0.1 μm when the leachant was replaced frequently. Overall, the results suggest that release of actinides from Synroc are controlled by solubility limiting effects at the surface area to volume ratios employed in MCC-1 tests.
Demonstration of the defense waste processing facility vitrification process for tank 42 radioactive sludge – melter feed preparation
Authors: Fellinger T. L. , Bibler N. E. , Marshall K. M. , Crawford C. L. , Hay M. S. 
Published: April 2011

AbstractThe Defense Waste Processing Facility (DWPF), at the Savannah River Site (SRS), is processing and immobilizing the radioactive high level waste sludge at SRS into a durable borosilicate glass for final geological disposal. The DWPF is currently processing the second, million gallon batch of radioactive sludge. This second batch is primarily from Tank 42. Each time a new batch of radioactive sludge is to be processed by the DWPF, the process flowsheet is to be tested and demonstrated to ensure an acceptable melter feed and glass can be made. This demonstration was completed in the Shielded Cells Facility in the Savannah River Technology Center at SRS.This paper presents the processing and offgas data, and compositional analyses obtained during the preparation of a melter feed for this demonstration. A second paper in this conference describes the properties of the glass produced from this feed. The demonstration used Tank 42 sludge slurry and the DWPF process control strategy for blending the sludge slurry with Frit 200 to make an acceptable melter feed. To prepare feed for the melter, the flowsheet requires that the radioactive sludge slurry be treated with nitric and formic acid to adjust rheology and remove mercury. During this step, hydrogen is formed from the decomposition of the formic acid. The acidified sludge slurry is then mixed with the prescribed amount of glass forming frit and evaporated to the proper weight percent solids to prepare feed to the melter. During this step hydrogen is also formed. Results indicate that the H2 generation rate is below the DWPF safety limits and an acceptable melter feed was produced.