bluuebunny/crossref_metadata_2025_split huggingface dataset:
Formation and Durability of Hydrated Layers for Several Oxide Glasses
Authors: Nishii Junji , Akai Tomoko , Yamashita Masaru , Yamanaka Hiroshi , Wakabayashi Hajimu 
Published: April 2011

AbstractFormations and durabilities of hydrated layers were compared between a soda-aluminosilicate (NAS), a soda-lime-aluminosilicate(NCAS) and a soda-lime-alumino-borosilicate(NCABS) glasses. The first step of our study was to prepare the optically transparent hydrated layers on the surface of specimens by an autoclave(400 °C, 20 kgf/cm2) treatment. Distributions of OH groups in hydrated layers were analyzed by an etch sectioning and FTIR measurement. The rates of hydration of the glasses were in the order NAS»NCAS>NCABS. The hydration of the NCABS glass, which is a modified nuclear waste glass, required the treatment longer than those of the NAS and NCAS glasses. In the second step, we investigated the durabilities of hydrated layers by immersing the specimens into a distilled water at 100 °C. The dissolutions of hydrated layers were confirmed for each glass. The dissolution rates of hydrated layers were in the order NCAS>NCABS»NAS. It has become apparent by an XPS analysis that the highest durability of the hydrated NAS glass was due to the formation of a sodium free Al2O3-SiO2 layer on the surface. The hydrated layer of the NCAS glass, while the sodium ions were almost leached out during immersion, dissolved to water most quickly than those of other glasses. In the hydrated layer of the NCABS glass, a half amount of sodium and boron ions remained and inhibited the dissolution of hydrated layer.
Flow-Diversion Barriers for HLW and LLW Disposal Under Partially Saturated Conditions
Authors: Apted M. J. , Salter P. F. , Conca J. L. 
Published: April 2011

AbstractAn innovative EBS design of sand-gravel layers for waste disposal under partially saturated conditions is described. Advantages of this EBS are 1) as a hydraulic barrier to advective inflow from the surrounding rock, and 2) as a diffusion barrier to the transport of dissolved or colloidal radionuclides. This sand-gravel barrier design for unsaturated sites is analogous to EBS designs using compacted bentonite backfills/buffers in saturated repository sites. Percolation box experiments, field tests, and natural analogues supporting the advantageous performance of this flow-diversion design are described and estimates for source-term release are calculated.
Study of the Leaching Behaviour of Sintered UO2 in Groundwater Using Nuclear Microprobe Techniques
Authors: Trocellier Patrick , Gallien Jean Paul , Cachoir Christelle , Toulhoat Pierre 
Published: April 2011

AbstractThe leaching behaviour of sintered UO2 pellets has been studied in synthetic groundwater at 96 °C under strictly controlled conditions (CO2 partial pressure, O2 partial pressure, pH and redox potential). Results obtained in oxidizing conditions (O2 content varying from 5 to 25 ppm) show a strong initial uranium release in solution during the first five days and a solubility control essentially driven by the growth of U(VI) species such as oxides, hydrates and carbonates. Results obtained in reducing conditions (use of a mineralogical buffer of Ni(0)/Ni(ll) with E0 = -0.257 Volts) show a very weak uranium release in solution close to 10-11 mole/l and a solubility control essentially driven by the formation of U(IV) compounds such as coffinite or uraninite.
Prediction of the Oxidative Dissolution Rates of Used Nuclear Fuel in a Geological Disposal Vault Due to the Alpha Radiolysis of Water
Authors: Sunder S. , Shoesmith D.W. , Miller N.H. 
Published: April 2011

AbstractEffects of alpha radiolysis of water on the corrosion of nuclear fuel (UO2) have been investigated in solutions at pH = 9.5, i.e., a value close to that expected in groundwaters at the depth of the disposal vault proposed in the Canadian nuclear fuel waste management program, CNFWMP. The corrosion potentials of UO2 electrodes exposed to the products of alpha radiolysis of water were monitored as a function of alpha flux and exposure time in a specially designed thin-layer cell. The oxidative dissolution rates of UO2 are calculated from the steady-state values of the corrosion potential using an electrochemical model. A procedure to predict the dissolution rate of used nuclear fuel in groundwater as a function of fuel cooling time is described, and illustrated by calculating the dissolution rates for the reference used fuel in the CNFWMP (Bruce CANDU reactor fuel, burnup 685 GJ/kg U). It is shown that the oxidative dissolution of used fuel in the CNFWMP will be important only for time periods ≤ 600 a at this burnup and assuming no decrease in pH.
Crevice Corrosion - NaCl Concentration Map for Alloy 625 at Elevated Temperature
Authors: Amano Toshiaki , Kojima Yoichi , Tsujikawa Shigeo 
Published: April 2011

AbstractThe repassivation potentials, Er.crev’s, for metal/metal-crevice of Alloy 625 were determined in 0.3–10% NaCl solutions for temperatures up to 250 C. The Er.crev’s were found to be the least noble at temperatures around 100 and 125 C. The Er.crev became more noble as temperature increased; this tendency was particularly strong in diluted solutions. Based on the experimental data, a crevice corrosion map showing the critical condition in terms of temperature and NaCl concentration was presented. As for the map, a wide repassivation region was found in elevated temperatures, similar to that of commercially pure titanium, C.P.Ti.
Development of Secondary Phases on Synroc Leached at 150˚C
Authors: Lumpkin Gregory R. , Smith Katherine L. , Blackford Mark G. 
Published: April 2011

AbstractElectron microscopy techniques were used to identify secondary phases on the surface of Synroc after exposure to doubly deionized water (DDW) at 150 ˚C for time periods up to 532 days. After one day, Ti02 develops on perovskite in the form of polycrystalline crusts of anatase or epitaxial crystals of brookite (± anatase), and as scattered single crystals on hollandite and rutile-Magnéli phases. With increasing exposure time the anatase crusts exhibit slow grain growth and development of preferred orientation; whereas, the epitaxial brookite crystals appear to grow more rapidly. Dissolution of perovskite and P-bearing intermetallic particles results indirectly in the precipitation of monazite after 84 days. Additional alteration products observed over a range of time include crystalline Al-O-H phases and amorphous to poorly crystalline Fe-O-H phases which form as a result of the dissolution of Al-rich oxides and Fe-bearing intermetallic grains, respectively. A poorly crystalline Ru-O-H phase was found as an alteration product of Ru-bearing intermetallic particles after exposure to DDW for 336 days.
Characterization of Highly Waste Loaded Glass for HLW
Authors: Kawamura Kazuhiro , Ohuchi Jin 
Published: April 2011

AbstractPossibility of highly waste loaded borosilicate glasses up to 65wt% were investigated for HLW. In the case the waste was loaded at a content higher than 45wt%, apatite crystal was identified in the glasses. Adding above 2.5wt% of M0O3, yellow phase was observed in the 45wt% waste glass. In the case the composition of actual waste was simulated, waste(25–45wt%) glasses were characterized. Chemical durability of 45wt% waste glass was equivalent to that of 25wt% waste glass under the condition of Na20 content lower than 12wt%. Rheological behavior of 45wt% waste glass was equivalent to that of 25wt% waste glass in the range of melting temperature. Electrical resistivity of 45wt% waste glass were a little lower than that of 25wt% waste glass and it depended on the noble metal content. The Time-Temperature-Transformation (T-T-T) diagram and the leach rate of heat treated glass indicated a good thermal stability of highly waste loaded glass below the glass transition temperature. Possibility of high waste loading up to 45wt% was elucidated.
Generation Mechanism of Hydrogen Gas from Hardened Cement Paste by γ-Irradiation
Authors: Noshita K. , Nishi T. , Matsuda M. 
Published: April 2011

AbstractHydrogen gas is generated from cementitious waste forms by radiolysis of water. In the case of low level radioactive waste, gas yields have been confirmed to be sufficiently low by irradiation experiments. However, studies have suggested that the hydrogen generation rate in cementitious waste forms is larger than the rate calculated from the g-value (H2 yields for 100eV absorbed). In this paper, the factors that increase the gas generation were investigated quantitatively. Two factors were identified, the effect of an organic diethylene glycol which reacts with hydrogen radicals to produce hydrogen, and the effect of electrons generated in the cementitious matrix which decompose water to hydrogen. The hydrogen generation rate was confirmed to drop less than the rate calculated from the g-value when these factors were eliminated.
Ion Mixing of Pulsed Laser Deposited Hydroxylapatite (HA)
Authors: Alford T.L. , Russell S.W. , Pizzicont V.B. , Mayer J.W. , Levine T.E. , Nastasi M. , Cotell C.M. , Auyeung R.C.Y. 
Published: April 2011

AbstractThe use of ion-beam techniques to enhance selected properties of bioactive materials, such as the adhesion of hydroxylapatite (HA) coatings on titanium-based substrates has been investigated. In this study, very thin HA films on titanium substrates were created by pulsed laser deposition techniques. Ion irradiations were carried out using 260-keV argon ions, with fluences of 0.25-50×1015ions/cm2, and at room temperature. Rutherford backscattering spectrometry was used to evaluate sample composition before and after irradiation. The amount of mixing was quantified by the mixing rate (the amount of atomic displacement due to an irradiation fiuence). This pilot data indicates that mixing was evident after sufficient ion irradiation. The ramification of this preliminary study has provided a quantitative measure of ion mixing as a potential prosthetic biomaterial surface modification technique.
Anomalous Diffusion of Implanted Chlorine in Silicon
Authors: Datar Sameer A. , Gove H. E. , Teng R. , Lavine J. P. 
Published: April 2011

AbstractThe diffusion of implanted chlorine in silicon wafers is studied with neutron activation/accelerator mass spectroscopy (NA/AMS). Depth profiles are obtained from as-implanted and annealed samples. While there is a marked difference between the annealed and as-implanted profiles for the lowest implant dose studied, 1013/cm2, the chlorine from the higher dose implants is virtually immobile. The diffusion of implanted chlorine in silicon is characterized by the apparent absence of indiffusion for the experimental conditions studied. However, outdiffusion is rapid at low concentrations for anneal temperatures of 1100°C and above. This behavior is qualitatively similar to that reported for fluorine in silicon at lower temperatures.
A Study of Loop Evolution During Inert Ambient Annealing and Reaction Between Point Defects and Dislocation Loops During Oxidation of Silicon
Authors: Liu J. , Jones K. S. 
Published: April 2011

AbstractIn the first part of this work, a plan-view TEM study has been made of the time-dependent annealing behavior of end of range (type II) dislocation loops introduced by lxl015/cm2 50KeV Si+ implantation into silicon. The activation energy for loop growth was determined to be 1.0±0.2eV from the Arrhenius plot of loop growth rate versus the reciprocal of annealing temperature. In the second part of this study, a thin boron layer was used as a diffusion monitor. The number of injected interstitials as a result of oxidation was measured by TEM. The diffusivity of boron with and without the presence of loops was studied by fitting experimental SIMS profiles with FLOOPS simulations. The interaction between loops and interstitials was determined to be diffusion limited.
A New Approach To Microporous Materials — Application Of Ion Beam Technology To Polyimides Membrane
Authors: Xu X.L. , Dolveck J.Y. , Boiteux G. , Escoubes M. , Monchanin M. , Dupin J.P. , Davenas J. 
Published: April 2011

AbstractRecently engineered porous materials have been attracted more attentions because of their potential applications in several industrial sectors, such as high efficiency gas separation membrane, catalytic membranes for chemical processing and so on. In spite of their desirable applications, these porous materials have not been realized due to several technical barriers, for example, lack of pore size control. There is a general viewpoint that for conventional gas separation membranes one cannot increase both permeability and permselectivity of the product gas simultaneously. This general viewpoint implies that the conventional methods of gas separation membrane fabrication cannot precisely control the pore size. In this work iodine diffusion property and gas permeation properties of ion beam irradiated polyimides films have been investigated. Small fluence irradiation can raise significantly the iodine penetration in the energy deposition range and permeabilities of the films both for H2 and CH4. After higher fluence irradiation, the implanted layers become stopping layers blocking iodine diffusion into the film and both the permeability for H2 and permselectivity for (H2/CH4) of the film increase hugely. We related the small fluence effects to defects created by irradiation and higher dose effects to the new materials formation of which the pore size is well defined. From these results we can perhaps have a peep at a new way to microporous materials.
Contamination Monitoring Using Surface Photovoltage and Application to Process Line Control
Authors: Jastrzebski Lubek , Lagowski Jacek , Henley Worth , Edelman Piotr 
Published: April 2011

AbstractSurface photovoltage (SPV) measurements of lifetime and charge are used by the silicon industry for real-time, non-contact monitoring of alkalide and heavy metal contamination during IC processing. Information about contamination present at the surface or in the bulk of a silicon wafer is derived from their effects on measured electronic characterization. Identification and detection, with a sensitivity of ppq (107 cm'3), of Fe and Cr in the bulk of p-type silicon is possible via monitoring of their decomposition/pairing kinetics with boron. We will show the most important examples of the application of SPV to monitor critical IC processing steps. The allowable contamination thresholds in IC processing lines are a very strong function of technology and are different for various metals.
Monitoring of the Early Stages of Thin Film Growth by the Generation From Second Harmonic Radiation of Supported Metal Particles
Authors: Götz T. , Hoheisel W. , Buck M. , Dressier C. , Eisert F. , Träger F. 
Published: April 2011

AbstractOptical second harmonic generation (SHG) of metal clusters supported on a dielectric substrate has been investigated. The SHG intensity was detected in situ as a function of cluster size during the nucleation of the particles at constant number density. SH radiation is detectable for particles as small as approximately 1 nm. In further experiments the chemisorption of oxygen on the surface of the metal particles was studied. The SHG signal strongly decreases as a function of oxygen coverage and disappears almost completely upon chemisorption of only one monolayer.
Correlation of Roughness, Impurity, Infra-Red Emissivity and Sputter Conditions for Aluminium Films
Authors: Wang C.H. , Shih W.C. , Somekh R.E. , Evetts J.E. , Jackson D. 
Published: April 2011

AbstractWe report the results of a study of IR emissivity of aluminium films as a function of impurity level, film thickness and sputtering conditions. Preliminary work suggests that for a given level of film impurities and deposition conditions, the JJR emissivity can be minimized with a certain film thickness. The influence of impurity level, film thickness, and sputter pressure on IR emissivity has been correlated with the resistivity and the surface roughness (measured by atomic force microscopy). The results are discussed in the general context of the Drude theory with allowances for the observed roughness.
Ion-Assisted Pulsed Laser Deposition of Amorphous Tetrahedral-Coordinated Carbon Films
Authors: Friedmann T.A. , Tallant D.R. , Sullivan J.P. , Siegal M.P. , Simpson R.L. 
Published: April 2011

AbstractA parametric study has been performed of amorphous tetrahedral carbon (a-tC) films produced by ion- assisted pulsed laser deposition (IAPLD). The ion voltage, current density, and feed gas composition (nitrogen in argon) have been varied. The resultant films were characterized by thickness, residual stress, Raman spectroscopy, and electrical resistivity. The Raman spectra have been fit to two gaussian peaks, the so called graphitic (“G”) peak and the disorder (“D”) peak. It has been found that the magnitude of the D peak and the residual compressive stress are inversely correlated. At low beam voltages and currents, the magnitude of the D peak is low, increasing as the ion beam voltage and current are raised. The ion beam voltage has the most dramatic effect on the magnitude of the D peak. At low voltages (200–500 V) the magnitude of the D peak is greater for ion beams with high percentages of nitrogen possibly indicative of C-N bonding in the films. At higher voltages (500 - 1500V) the D peak intensity is less sensitive to the nitrogen content of the beam.
A Numerical Simulation of Pulsed Laser Deposition
Authors: Laughlin William T. , Lo Edmond Y. 
Published: April 2011

AbstractA numerical simulation of the pulsed laser deposition process has been developed. This model is applied to pulsed laser deposition of carbon, a solid lubricant material. At laser fluences above the ablation threshold, the vapor density and temperature at the substrate are sufficiently high that a continuum flow exists. For typical pulsed laser deposition parameters, plume vapor temperatures and densities are insufficient for significant ionization. However, plume absorption does take place and is regulated by wavelength dependent absorption cross sections of the molecular species. Vapor expansion velocities depend on the absorption of laser radiation and thus the laser wavelength. A simple kinetic theory of deposition predicts the film deposition rate and film thickness profile.
Composition and Phase Control for Molybdenum Nitride thin Films
Authors: Mudholkar Mandar S. , Thompson Levi T. 
Published: April 2011

AbstractMolybdenum nitrides are active and selective hydrodenitrogenation (HDN) catalysts. The catalytic properties of molybdenum nitrides were found to be dependent on the structural properties. The purpose of research described in this paper was to synthesize molybdenum nitride thin films with well defined structures and stoichiometries using ion beam assisted deposition. The films were deposited by evaporating Mo metal, and simultaneously bombarding the growing film with low energy nitrogen ions. The phase constituents of the films were determined using x-ray diffraction and the film composition was obtained by Rutherford backscattering spectrometry.The film composition and phase constituents were strong functions of the ion-to-atom arrival rate ratio, ion energy and ion angle of incidence. Differences in the film composition for different arrival rate ratios and ion angles of incidence were interpreted based on reflection and sputtering effects. Our results suggest that phase formation was governed by the effective energy density per deposited atom. Evaluation of the effective energy density per deposited atom and its physical significance in ion beam assisted deposition is discussed.
EPR Studies of E-Beam and Gamma Irradiated ZnGeP2: A Nonlinear Optical Material for the Infrared
Authors: Rakowsky M.H. , Lauderdale W.J. , Mantz R. A. , Pandey R. , Drevinsky P.J. 
Published: April 2011

AbstractZinc germanium phosphide is a nonlinear optical material for efficient frequency conversion in the mid-IR spectral region. One challenge in the development of ZnGeP2 is to reduce the near band edge absorption in the 0.7 to 2.5 micron region. Several methods have been used to ascertain the origin of this absorbance. One method, electron paramagnetic resonance (EPR), has been used to characterize the paramagnetic native acceptor in ZnGeP2 by studying as-grown, thermally annealed, electron-beam irradiated, and gamma irradiated single crystals. Each of the these processing routines improves the optical transparency with a concurrent decrease in the concentration of paramagnetic centers and defect site symmetry as seen in the EPR spectra. High energy e-beam and gamma irradiation may cause compensation, movement, or creation of new defects. In addition, nuclear magnetic resonance (NMR) has been used to further characterize several samples of as-grown, annealed and polycrystalline ZnGeP2. Preliminary calculations of the defect energetics have been conducted using atomistic simulation techniques employing the shell model to describe the lattice. Interionic potentials between the constituent ions were obtained by performing quantum cluster calculations on ZnGeP2.
Characterization and Performance of Carbon Films Deposited by Plasma and Ion Beam Based Techniques
Authors: Walter K.C. , Kung H. , Levine T. , Tesmer J.T. , Kodali P. , Wood B.P. , Rej D.J. , Nastasi M. , Koskinen J. , Hirvonen J-P. 
Published: April 2011

AbstractPlasma and ion beam based techniques have been used to deposit carbon-based films. The ion beam based method, a cathodic arc process, used a magnetically mass analyzed beam and is inherently a line-of-sight process. Two hydrocarbon plasma-based, non-line-of-sight techniques were also used and have the advantage of being capable of coating complicated geometries. The self-bias technique can produce hard carbon films, but is dependent on rf power and the surface area of the target. The pulsed-bias technique can also produce hard carbon films but has the additional advantage of being independent of rf power and target surface area. Tribological results indicated the coefficient of friction is nearly the same for carbon films from each deposition process, but the wear rate of the cathodic arc film was five times less than for the self-bias or pulsed-bias films. Although the cathodic arc film was the hardest, contained the highest fraction of sp3 bonds and exhibited the lowest wear rate, the cathodic arc film also produced the highest wear on the 440C stainless steel counterface during tribological testing. Thus, for tribological applications requiring low wear rates for both counterfaces, coating one surface with a very hard, wear resistant film may detrimentally affect the tribological behavior of the counterface.
Negative-Ion Implantation
Authors: Ishikawa Junzo 
Published: April 2011

AbstractNegative-ion implantation is a promising technique for forthcoming ULSI (more than 256 M bits) fabrication and TFT (for color LCD) fabrication, since the surface charging voltage of insulated electrodes or insulators implanted by negative ions is found to saturate within so few as several volts, no breakdown of insulators would be expected without a charge neutralizer in these fabrication processes. Scatter-less negative-ion implantation into powders is also possible. For this purpose an rf-plasma-sputter type heavy negative-ion source was developed, which can deliver several milliamperes of various kinds of negative ion currents such as boron, phosphor, silicon, carbon, copper, oxygen, etc. A medium current negative-ion implanter with a small version of this type of ion source has been developed.