bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theory and Calculation of Water Distribution in Bentonite in a Thermal Field
Authors: Carnahan C. L. 
Published: March 2011

ABSTRACTAnalysis of observed distributions of water adsorbed by compacted MX-80 bentonite in the presence of temperature gradients according to methods of the thermodynamics of irreversible processes indicates the possibility of coupling among fluxes of heat and mass. Additional experiments are suggested to confirm the existence of coupling.
Modeling Studies of Multiphase Fluid and Heat Flow Processes in Nuclear Waste Isolation
Authors: Pruess Karsten 
Published: March 2011

ABSTRACTMultiphase fluid and heat flow plays an important role in many problems relating to the disposal of nuclear wastes in geologic media. Examples include boiling and condensation processes near heat-generating wastes, flow of water and formation gas in partially saturated formations, evolution of a free gas phase from waste package corrosion in initially water-saturated environments, and redistribution (dissolution, transport, and precipitation) of rock minerals in non-isothermal flow fields. Such processes may strongly impact upon waste package and repository design considerations and performance.This paper summarizes important physical phenomena occurring in multiphase and nonisother-mal flows, as well as techniques for their mathematical modeling and numerical simulation. Illustrative applications are given for a number of specific fluid and heat flow problems, including: ther-mohydrologic conditions near heat-generating waste packages in the unsaturated zone; repository-wide convection effects in the unsaturated zone; effects of quartz dissolution and precipitation for disposal in the saturated zone; and gas pressurization and flow effects from corrosion of low-level waste packages.
Interactions and Transport of Plutonium-Humic Acid Particles in Groundwater Environments
Authors: Bidoglio G. , De Plano A. , Righetto L. 
Published: March 2011

ABSTRACTPu adsorption on pure γ-alumina and heterogeneous mineral phases was investigated as a function of pH and humic acid (HA) concentration. Information on surface speciation was obtained by using various actinides as valence analogues for Pu. Surface redox transformations of Pu(V) appeared to control Pu uptake onto electron exchanging minerals. A one-dimensional transport experiment of high molecular weight HA in water saturated clayey sand column was performed under reducing conditions (Eh <-200 mV). This showed that HA particles larger than 600 nm were retained in the column. The HA breakthrough curve was characterized by extended tailing. Physico-chemical interactions at the mineral surface and particle straining in smaller pore spaces appeared to control HA transport through the soil. The chemical association of Pu with moving HA was investigated by leaching of 238-Pu-doped borosilicate glasses. Enhancement in Pu release rate was observed in HA solutions compared with organic-free groundwater.
The Solubility of Amorphous and Crystalline Schoepite in Neutral to Alkaline Aqueous Solutions
Authors: Bruno Jordi , Sandino Amaia 
Published: March 2011

ABSTRACTThe solubility of schoepite, UO2(OH)2 H2O, has been investigated by potentiometric titration at 25 °C in 0.5 mol dm.−3 NaClO4 solution. The data indicates the predominance of the species (UO2)3(OH)5+ and either UO2(OH)3− or (UO2)3(OH)7− in the pH range studied. The formation constants of these species as well as the solubility product of the amorphous and microcrystalline schoepite have been determined. The consequences of these data on the hypothesis of schoepite as the solubility limiting phase in spent fuel dissolution studies is discussed.
Uranium Transport and the Partitioning of U, Th, and Ra Isotopes Between Solid and Aqueous Phases in the Krunkelbach Mine, Federal Republic of Germany
Authors: Dearlove Jeremy P.L. , Green D. C. , Ivanovich M. 
Published: March 2011

ABSTRACTThis paper discusses some of the results from a natural geochemical analogue study on the Krunkelbach mine, F.R.G. These data, based largely on uranium series disequilibrium measurements, are used to compare the results of groundwater modelling programmes with observations made in the mine.
Sorption Properties of Natural Sulfides with Respect to Technetium
Authors: Bock W.-D. , Brühl H. , Trapp C. , Winkler A. 
Published: March 2011

ABSTRACTTechnetium sorption properties of Fe2+-bearing minerals and different metal sulfides were studied by batch and column experiments. Pure stibnite (SbS3), pyrrhotite (FeS), pyrite (FeS2), galena (PbS) and loell ingite (FeAs2) fix Tc to a great extent (> 95 % of TcO4- starting inventory). They appear to be favourable backfill materials for redox-sensitive radionucli-des. Physico-chemical processes of fixation and possible fixation modes are discussed.
Aluminum Atom Surface Mobility on SiO2 During Ionized Cluster Beam Deposition
Authors: Levenson Leonard L. , Swartzlander Amy B. , Usui Hiroaki , Yamada Isao , Takagi Toshinori 
Published: March 2011

ABSTRACTAn ionized cluster beam (ICB) source was used to deposit Al onto SiO2 substrates. A 60 gtm diameter wire held at the substrate served as a mask. After Al deposition, the wire was removed and the masked area was examined by scanning electron microscopy (SEM) and by scanning Auger microprobe (SAM). The ICB source was operated at 0, 3, and 6 kV acceleration voltages. The substrate was held at 80°, 200°, and 400°C during Al depositions. The Al deposition rate averaged 240 A per min. The chamber pressure during deposition was 2×10-6 Torr. The diffusion distance of Al under the mask edge was determined from the SEM micrographs and SAM line scans. The maximum diffusion distance for all acceleration voltages occured at a substate temperature of 200°C. The maximum diffusion distance at 200°C was 29 μm at 6 kV acceleration voltage. The minimum diffusion distance was 12 μm at 400°C for an acceleration voltage of 6 kV.
The Infidence of Defect Concentrations on Migration Energies in AgZn Alloys
Authors: Andreadis T. D. , Rosen M. , Eridon J. M. , Rosen D. J. 
Published: March 2011

ABSTRACTMigration energies in Ag of vacancies, interstitials, Zn impurity atoms, interstitial-iipurity cumplexes, and vacancy-impurity complexes were calculated using Embedded Atom. Method (EAM) potentials in Molecular Statics calculations. A new Zn EAM potential was determined and used in these calculations. The dependence of the migration energies on local defect concentrations was determined in a linear approximation. Binding and formation energies of defects are also presented. A new model for the migration energy appropriate for defect reactions is introduced.
Superadditivity in the Implantation of Molecular Ions
Authors: Cerofolini G. F. , Meda L. , Volpones C. 
Published: March 2011

ABSTRACTThis paper deals with the implantation of molecular ions in silicon. The ‘molecular’ effect, i.e. the increase of the displacement yield compared with the sum of the atomic yields, is weak for light molecules (e.g., H2) and for heavy diatomic molecules (e.g., Sb2 and Bi2), but, for instance, it is strong for C6H6 at energy per atomic mass of the order of 1 keV/amu. Binary collision calculations are used to give a pictorial view of the phenomena occurring along the ion path, and to predict superadditivity and damage columnarity. The increase of pressure and temperature to extreme conditions by implantation of molecular ions is discussed.
Magnetic Anomaly and Icosahedral Phase Formation in Fe-Cu and Fe-Mo Systems
Authors: Huang L. J. , Chen Q. M. , Liu B. X. , Fan Y. D. , Li H-D. 
Published: March 2011

ABSTRACTThe first observation of a new class of icosahedral phase associated with a magnetic transition in Fe-Cu and Fe-Mo systems are reported. It is found that the icosahedral order can be re-established when the destabilized Fe60Cu40 icosahedral phase subject to a magnetic transition at high annealing temperature. The Fe70Mo30 amorphous films obtained by sputtering exhibit a similar behavior at high magnetic transition temperature. A brief discussion of the observed phenomena is addressed.
Morphology of Amerphous Alloy Formed by Ion Beam Bombardment
Authors: Wei Tian , Ping Cai Wei , Jun Li , Run Wu 
Published: March 2011

ABSTRACTA study was performed to investigate the morphology of amorphous alloys which were formed on the surface of the samples by means of ion beam bombardment. The specimens of Fe deposited with Cr, Ti, Cr-Ni or Cr-Ni-Cr multilayers were bombarded by high doses of Ar+, N+ or Ti+ ion beams respectively. TEM and electron diffraction analysis were then used to study the kinetic transformation of amorphous to crystal during heating. The electro-chemical results hlvn showed after that the anodic current density Ic and Im were reduced remarkably.
Thermally and Ion-Induced Reactions of Metal with CuO Substrate
Authors: Li Jian , Wang S. Q. , Mayer J. W. 
Published: March 2011

ABSTRACTThermally and ion-induced reactions of transition metals Zr, Ti, Cr and Ag with CuO substrates have been studied by Rutherford backscattering spectrometry and X-ray diffraction techniques. Reactions resulted in the configuration of ZrO2/Cu2O/CuO from Zr/CuO structure and TiOx/Cu2O from Ti/CuO structure after thermal annealing and ion irradiation. No significant reaction has been found in Cr/CuO after vacuum annealing at 410°C and 300 Key Xe ions irradiation at 240°C. Ag atoms balled up on CuO surface after annealing at 610°C. A comparison of the reaction layers has been made in both metal/SiO2 and metal/CuO systems after thermal annealing and ion irradiation. Both heats of reaction and bond strength in the substrates can influence the chemical reactivity between metal layer and substrate.
In Situ Hvem Study of Ion Irradiation-Induced Grain Growth in Au Thin Films
Authors: Liu Joyce C. , Li Jian , Mayer J. W. , Allen Charles W. , Rehn Lynn E. 
Published: March 2011

ABSTRACTIn situ observations of 1.5 MeV Xe+ ion irradiated Au films at room temperature and at 150°C reveal the evolution of grain growth: the average grain size increases by the mechanisms of grain boundary migration and grain coalescence.
Radiation Induced Amorphization in YBa2 Cu3O7 and GdBa2 Cu3O7 Superconductors
Authors: Parkin Don M. , Nastasii Michael 
Published: March 2011

ABSTRACTThe response of YBa2Cu3O7 and GdBa2Gu3O7 high temperature superconductors to particle irradiation is examined. Both ion and electron irradiations have been shown to first produce an orthorhombic-to-tetragonal transformation at relatively low doses followed by a tetragonal-to-amorphous transformation at doses roughly a factor of 10 higher. Analysis of the displacement stoichiometry that results from 120, 300, and 1000 keV electron irradiations, 400, and 500 keV O irradiations, and 300 keV helium irradiations indicate that the orthorhombic-to-tetragonal transformation is driven by O atom displacements either alone or in the presence of metal atom displacements and that the transformation to the amorphous phase is driven by displacements on the Y, Gd or other rare earth atom site.
0.5 MeV Submicron Ion Probe System for RBS/PIXE.
Authors: Inoue K. , Takai M. , IshibashI K. , Kawata Y. , Suzuki N. , Namba S. 
Published: March 2011

ABSTRACTA nuclear microprobe-forming system for the microscopic RBS/PIXE measurement of micro devices has been developed and installed at the Research Center for Extreme Materials, Osaka University. The use of precision quadrupole magnets and an objective collimator ensures a final spot size of less than 1μm.
Enhanced Wear Resistance by Compressive Strengthening a Novel Combination of Laser and Ion Implantation Technology
Authors: Beurs H. De , Hosson J. Th. M. De 
Published: March 2011

ABSTRACTDespite the advantages of laser processing for the production of wear resistant materials, laser surface melting results in tensile stresses because the melted layer shrinks during resolidification. These tensile stresses may lead to severe cracking of the material and to deleterious effects on the wear behaviour. Our basic idea presented in this paper is to convert the high tensile stresses in the laser melted surface into a compressive state after implantation. In general, neon implantation is not very effective in the reduction of wear rates. However, neon implantation into laser melted steel turns out to reduce the wear rate substantially.
Unlubricated Sliding Properties of Ion Beam and Excimer Laser Mixed Fe-Ti-C Multilayered Films
Authors: Hirvonen J-P. , Nastasi M. , Jervis T. R. , Tesmer J. R. , Zocco T.G. 
Published: March 2011

ABSTRACTMultilayered Fe-Ti-C films consisting of eleven sublayers were vacuum deposited onto an AISI 304 stainless steel substrate and subsequently mixed using either 400 key Xe ions or an excimer laser operating at a wavelength of 308 nm. Ion mixing was accomplished in a two step process: the multilayers were first irradiated with 1×1017 Xe/cm2 at 520°C, after which half of the sample was irradiated with 5×1015 Xe/cm2 at 0 °C. Laser mixing was carried out at both i.i and 1.7 J/cm2 with the number of pulses varied between 1 and 10. Pin-on-disc studies revealed only slight differences between the two kinds of ion beam mixed samples, whereas the dry sliding properties of laser mixed samples were strongly dependent on the total fluence used. In the optimum conditions, similar friction coefficients were obtained on both kinds of samples.
Growth of Stoichiometric bn Films by Pulsed Laser Evaporation
Authors: Murray P. T. , Donley M. S. , McDevitt N. T. 
Published: March 2011

ABSTRACTThe feasibility of growing stoichiometric thin films of BN by pulsed laser evaporation has been investigated. Films grown under high vacuum conditions were N-deficient. This result is consistent with thermodynamic calculations, which indicate that B metal formation, with concomitant N2 desorption, is energetically favored over BN formation. Stoichiometric films were grown in NH3 with substrate temperatures of 400, 500, and 1000°C. Analysis of films grown under these conditions by grazing incidence x-ray diffraction indicates the films to be highly oriented, hexagonal BN.
Effects of Ion Bombardment on the Environmental Durability of Silver Coatings
Authors: Al-Jumaily G. A. , Mooney T. A. , Smajkiewicz A. 
Published: March 2011

ABSTRACTEffects of ion bombardment during deposition on the environmental durability of silver coatings have been examined. Films deposited under otherwise identical conditions were bombarded at different levels with 300 eV argon ions. Examination of the environmental durability of coatings revealed that films deposited with ion assisted deposition are more durable than evaporated coatings. Adhesion and scratch resistance of coatings were also improved as a result of ion bombardment.
Ion-Assisted Deposition of Protective Overlayers for Magneto-Optic Alloys
Authors: Cornett Kenneth D. , Gibson Ursula J. , Taylor Anthony 
Published: March 2011

ABSTRACTRare-Earth Transition-Metal alloys such as Tb-Fe-Co are being studied and used as magneto-optic data storage materials. These materials are susceptible to oxidation by either oxygen or water vapor, particularly the rare earth component. Pitting corrosion is also a problem when protective overlayers have pinholes or a porous microstructure. Both degradation mechanisms are significant for application of this material to optical data storage. We have used ion assisted deposition (IAD) to produce protective overlayers of refractory oxides, such as Al2O2 and ZrO2. These layers were deposited both with and without IAD onto iron films and exposed to environments with controlled temperature and humidity. A scanning micro-reflectometer capable of detecting micrometer-sized pinholes was used to monitor the degradation of the iron layer with exposure time.
Segregation of Ag and Cu During Ion Beam and Thermally Induced Recrystallization of Amorphous Si
Authors: Custer J. S. , Thompson Michael O. , Poatet J. M. 
Published: March 2011

ABSTRACTThe segregation of Ag and Cu impurities in amorphous Si during both thermal and ion beam induced epitaxial crystallization has been studied. During thermal regrowth at 550°C, both Ag and Cu are initially trapped at increasing concentration in the shrinking a-Si layer. At a critical concentration, though, regrowth becomes non-planar and the impurities are no longer entirely trapped in the a-Si. Above 0.08 at% and 0.15 at% respectively, the excess impurity is lost to the crystal region and diffuses rapidly away from the interface. Under low temperature (200 - 400°C) epitaxy induced by a 2.5 MeV Ar+ beam, segregation and trapping are initially observed. As regrowth proceeds, however, the segregation no longer follows the simple model
Electrical Activation of Heavily Doped Arsenic Implanted Silicon
Authors: Said J. , Jaouen H. , Ghibaudo G. , Stoemenos I. , Zaumseil P. 
Published: March 2011

ABSTRACTThe combination of electrical, Transmission Electron Microscopy and Triple Crystal X-ray Diffraction measurements allow us to separate the existence of a local impurity activation process from the amorphous- crystal transformation. The local process occurs in the highly damaged surface layer induced by the arsenic implantation and is efficient well below the Solid Phase Epitaxy transition temperature. It is suggested that point defect migration should play an important role in the electrical impurity activation at low annealing temperatures.
Ion Bombardment Effects on GaAs Using 100eV Nitrogen Ions
Authors: Lau W. M. 
Published: March 2011

ABSTRACTThe ion bombardment effects of low energy molecular nitrogen ions (100eV) on GaAs have been investigated using in-situ polar angle dependent X-ray photoelectron spectroscopy. It was found that arsenic and gallium nitrides were formed as a result of the nitrogen ion bombardment. The ion bombardment also caused a depletion of arsenic in the near surface region. For example, with a dose of 6×1015 cm-2 of nitrogen molecular ions at 100eV, the surface structure can be described approximately as 1.5nm of Ga0.67A0.33N on GaAs. The ion bombardment moves the Fermi levels of both n-type and p-type GaAs to mid-gap. Heating the ion bombarded samples in a vacuum chamber to 500°C desorbs all arsenic nitrides but most of the gallium nitrides remain on the surface. The Fermi levels of both n-type and p-type are then stablized at about 0.4eV from the valence band maximum. A surface type-inversion of the n-type substrate is therefore induced by the nitrogen-ionbombardment/annealing treatment.
Effect of Microstructure on the Sheet Resistance of Ion-Beam Deposited ZnO Thin Film
Authors: Isa Saliman A. , Ghosh P. K. , Kornreich P. G. 
Published: March 2011

ABSTRACTZnO thin films were deposited by ion-beam sputtering technique. Preliminary results show that the films are stoichiometric and crystalline in nature. The microstructure of ZnO films obtained depends very much on the process parameters. Among these parameters is the substrate temperature whose effect has been carefully examined.ZnO films were deposited with substrate temperatures ranging from 200°C to 350°C. We observed that the sheet resistance of the films varies with their microstructure. In this investigation, a sheet resistance of 6.6 Mega-ohms per square is measured on a dense film deposited at a substrate temperature of 325°C.We present in this paper a correlation between the film's microstructure and stoichiometry with some of it's electrical properties.
Investigation of Titanium Nitride Synthesized by Ion Beam Enhanced Deposition
Authors: Jiankun Zhou , Xianghuai Liu , Youshan Chen , Zhihong Zheng , Wei Huang , Zuyao Zhou , Shichang Zou 
Published: March 2011

ABSTRACTTitanium nitride films have been synthesized at room temperature by alternate deposition of titanium and bombardment by nitrogen ions with an energy of 40KeV. The component depth profiles and the structure of titanium nitride films were investigated by means of RBS, AES, TEM, XPS and X-ray diffraction. The results showed that titanium nitride films formed by ion beam enhanced deposition (IBED) had columnar structure and were mainly composed of TiN crystallites with random orientation. The oxygen contamination in titanium nitride films prepared by IBED was less than that of the deposited film without nitrogen ion bombardment. It was confirmed that a significant intermixed layer exists at the interface. The thickness of this layer was about 40 nm for the film prepared on iron plate. The mechanical properties of the film have been investigated. The films formed by IBED exhibited high hardness, improved wear resistance and low friction.
Electrically Conducting Thin Films by Ion Implantation of Pyrolyzed Polyacrylonitrile
Authors: Basheer R. A. 
Published: March 2011

ABSTRACTHeat treatment of polyacrylonitrile leads to products with semiconductor to metal like conductivities. The electrical properties of these materials are further modified by ion implantation. It is noted that the conductivity (∼10-7 (Ω cm)-1) of heat treated Polyacrylonitrile at 435°C (PAN435) increases upon ion implantation with As+, Kr+, Cl+ of F+ reaching a maximum value of 8.9 × 10-1 (Ω cm)-1 at as does of 5 × 1016 ion/cm2 and an energy of 200 KeV for the case of F+ implantation. On the other hand, ion implantation of the more conducting heat treated PAN at 750°C (PAN750) leads to a decrease in the electrical conductivity of the material. It is proposed that the conductivity modifications are primarily due to structural rearrangements induced by the energetic ions. Specific chemical doping contribution to conductivity is noted for halogen implantation in PAN435. The temperature dependence of conductivity of PAN heat treated at 750°C suggests a two path conduction, namely, a three dimensional variable range hopping conduction and a metallic conduction. After ion implantation, the conductivity-temperature dependence is interpreted in terms of a variable range hopping conduction mechanism.
Depth Profiling of Ion Beam Induced Damage in Semiconductor Heterostructures
Authors: Germann R. , Forchel A. , Hörcher G. , Weimann G. 
Published: March 2011

ABSTRACTWe have produced beveled cross-sections of GaAs/GaAlAs multiple quantum well structures with inclination angles of 0.55 minutes of arc with a special ion beam etching technique. The extension of the damage which is induced during the dry etching process can be evaluated directly by a comparison of spatially resolved secondary ion mass spectroscopy and photoluminescence measurements. We observe a thickness of the damaged surface layer between 36 nm for 250 eV Argon ions and 160 nm for 1000 eV Argon ions in a GaAs/GaAlAs multiple quantum well structure.