bluuebunny/crossref_metadata_2025_split huggingface dataset:
Overview of the Major Phosphor Technologies
Authors: Yocom P. Niel 
Published: April 2011

ABSTRACTPhosphors are ubiquitously present in our everyday environment. The most common uses are in fluorescent lamps and display devices; e.g., TV tubes and computer displays. In addition, phosphors are used in medical radiology to transform the x-ray energy to light that is recorded on film for diagnostic purposes. The types of phosphors, mechanisms of operation, and future needs for these major phosphor technologies will be surveyed. In addition, brief mention will be made of some of the minor uses of phosphor materials.
Microstructural Characterization of Creep Tested Cryomilled NiAl-13vol. % AlN
Authors: Garg A. , Whittenberger J. D. , Aikin B. J. M. 
Published: April 2011

AbstractCryomilling of prealloyed NiAl powders, followed by extrusion, has been used to produce a particulate strengthened NiAl-13vol.% AlN material. At 1300 K, the compressive strain rate-flow stress diagram has two distinct deformation regimes, with the transition occurring near 150 MPa. The low and the high stress regimes have power law creep exponents of ∼ 6.1 and 14.2, respectively. Microstructural characterization of the as-extruded and tested samples has been performed to develop an understanding of the superior mechanical properties of the material. The microstructure of the as-extruded material was inhomogeneous and consisted of mantle regions containing a mixture of small NiAl grains (diameter ∼ 50–150 nm) and fine AlN particles (size ∼ 5–50 nm) that surround larger NiAl grains (diameter ∼ 0.3–8.0 μm) which were mostly particle free. In the low-stress regime, samples tested to steady state exhibited a structure composed of subgrain boundaries in the particle-free NiAl grains. In addition, some of the subgrains had developed a well defined dislocation network. AlN patricles occasionally found within large NiAl grains acted as pinning centers for dislocations. Small NiAl grains and the AlN particles constituting the mantle coarsened during these tests. In the high-stress regime, samples tested to steady state exhibited a high density of dislocations in most of the particle-free NiAl grains. Subgrain boundaries were found occasionally but dislocation networks were rare. The AlN particles had not significantly coarsened due to the shorter times at temperature.
Vapor Phase Synthesis of Ti Aluminides and the Interfacial Bonding Effect on the Mechanical Property of Micro-Composites Reinforced by Pyrolized SiC Fibers
Authors: Suzuki T. , Umehara H. , Hayashi R. 
Published: April 2011

AbstractVapor phase processings for manufacturing near-net-shaped composites, continuous fiber reinforced composites or lamellar composite will be hopeful methods. The method for synthesis of TiAl by a magnetron sputtering using a multiple target has been successfully established, and the tensile property of the microcomposite with SiC fibers has been studied. The TiAl produced by a vapor phase processing was evaluated by Auger electron spectroscopy and the x-ray analysis. The tensile strength properties of the SiC/TiAl microcompositesof which the interface bonding was controlled with the powers of sputtering were estimated. The properties of SiC/TiAl microcomposites are decreasing with increasing the sputtering power. The irradiation-cured SiC fiber has better compatibility with TiAl than the oxidation-cured SiC fiber. The strength of the microcomposite has been improved with using a thin C-coated irradiation-cured SiC fiber.
The EL Berrocal Project: Geological Characterisation and Radionuclide Migration Studies in a Fractured Granitic Environment
Authors: Miller W. M. , Pérez Villar L. , Gómez P. , Ivanovich M. , de la Cruz B. , Rivas P. , Hernán P. , Carrera J. , Guimerà J. , Holmes D. , Avogadro S. , Fernández J.-M. , Bruno J. 
Published: April 2011

AbstractEl Berrocal is an abandoned uranium mine in a mineralised quartz vein hosted by a Hercynian granite in central Spain. This mine is the focus of an international project to characterise and model natural elemental migration in a fractured-rock environment as an aid to understanding and predicting processes that may occur in a geological repository for radioactive wastes.Uranium in the mineralised quartz vein has been shown to have originated from the orthomagmatic uraninite in the granite with the elemental removal and migration occurring predominately by hydrothermal fluids. Mobilisation of uranium from the mineralised quartz vein and from granite adjacent to hydraulically-active fractures away from the vein occurred over the geologically-recent past and in the present-day. The most recent mobilisation is evidenced by dissolution features seen in SEM photomicrographs; mineral growth and sorption signatures identified by enhanced uranium concentrations on the surfaces of preexisting minerals; and measured disequilibrium in the uranium series for whole rock close to fracture walls.Present-day groundwaters in the studied area are young meteoric waters. They are generally calcium-sulphate enriched, oxidising and mildly acidic near the surface, becoming more bicarbonate-rich with near neutral pH in the deeper zones, except around the mineralised vein where the waters are acid (pH around 3) due to oxidisation of the sulphide minerals. No deep, chemically-reducing groundwaters have yet been identified in the El Berrocal boreholes.
Development of a Conceptual Flow-Path Model of Nuclide Migration in Crystalline Rock - A Case Study at the Kamaishi in-Situ Test Site, Japan -
Authors: Osawa H. , Sasamoto H. , Nohara T. , Ota K. , Yoshida H. 
Published: April 2011

AbstractThe objective of this study is to develop a conceptual flow-path model for nuclide migration in fractured crystalline rock at the Kamaishi In-Situ Test Site because improvement of existing models of matrix diffusion |e.g. 1,2|, based on realistic geological data, is necessary for a better understanding of nuclide migration into rock matrix. Data from field observations indicate that fractures at the Kamaishi In-Situ Test Site can be classified into three types; type A with a zone of fracture fillings, type B with a zone of fracture fillings and an altered zone, type C consisting of several fractures with a zone of fracture fillings and an altered zone. Fracture type B was studied in detail by laboratory experiments because type B is predominant in the studied area with more than 60 % of a total of 400 fractures observed in the fracture mapping. Data from laboratory experiments on core, crosscutting a water-bearing fracture and the surrounding rock, indicate that the zone of fracture fillings and the altered zone in the vicinity of the fracture contain flow-paths in which nuclides can migrate and be trapped. The fracture fillings contain more interconnected and permeable flow-paths than the altered and unaltered zones. This implies that migrating nuclides can access flow-paths in the altered zone. The altered zone adjacent to the zone of the fracture fillings contains flow-paths such as microfractures, cracks within quartz, and grain boundaries between altered minerals, through which nuclides will migrate from the fracture fillings into the altered zone and be trapped. The fracture fillings and the specimen of the altered zone have higher sorption capacity than the specimen of the unaltered zone. These data suggest that retention of nuclides can be expected in the vicinity of the fracture. In conclusion, a conceptual flow-path model consisting of a zone of fracture fillings, an altered zone, and an unaltered zone has been developed for a better understanding of nuclide migration in fracture type B.
Radionuclide Release from the Kbs-3 Repository-Sensitivity to the Variability of Materials and Other Properties
Authors: Romero L. , Andersson Å. , Moreno L. , Neretnieks I. 
Published: April 2011

AbstractRadionuclides leaking from a canister spread into the backfill material surrounding the canister and then migrate through different pathways into the mobile water in the rock fractures. In order to quantify uncertainties regarding the release to the far field, a sensitive analysis is performed for the uncertainties in the parameters governing the release.For nuclides escaping through a damaged canister in a repository of the type KBS-3 [1], most nuclides migrate through the pathways appointing to the fracture intersecting the deposition hole and the disturbed zone below the tunnel.The sensitivity analysis showed that the grade of impact on the release of uncertainties in the parameters cannot be generalized for all nuclides, however, some patterns of the influence can be given. Uncertainties in the hole size and uranium solubility for nuclides embedded in the matrix have a strong influence on the release. The adsorption capacity of the bentonite surrounding the canister and the hydraulic properties of the fractured rock in the short pathways to the mobile water have to be accurately known to reduce uncertainties in the release to the far field. For nuclides with a high diffusion coefficient in the bentonite, e.g. cesium and strontium, the hydraulic properties of the fractured rock nearest to the canister have to be well known. For the iodide, on the other hand, with a very low diffusion coefficient, uncertainties in the hydraulic properties have a very small effect on the release. The uranium release with a very high inventory is not affected by uncertainties in the hydraulic properties of the rock.The released nuclide fraction through each pathway is not largely influenced by uncertainties in the transport properties of the backfill materials whereas uncertainties in the water flow rates in the zones in the rock where the water flows, have a strong influence on the nuclide release distribution.
Non-Conservative Assumptions in the 1992 Performance Assessment for the Waste Isolation Pilot Plant
Authors: Neill R. H. , Lee W. W.-L. 
Published: April 2011

AbstractPerformance/safety assessments have been conducted for the Waste Isolation Pilot Plant, a repository for transuranic waste in salt. We challenge two key assumptions in the 1992 Performance Assessment that led to non-conservative results. The predicted release rate of radionuclides appears underestimated due to the use of expert elicited solubilities. The overall release has been underestimated due to the use of improperly elicited human intrusion probabilities.
A New Approach to the Selection of Materials for Engineered Barriers and Appropriate Host Rocks for High Level Waste Disposal
Authors: Omelianenko B.I. , Nikonov B.S. , Ryzhov B.I. , Shikina N.D. , Yudintsev S.V. 
Published: April 2011

AbstractSorptive properties of weathered dunites, gabbro-diabases and basic volcanic rocks for Sr and Cs were studied. The results show that the sorptive capacities of these rocks are equivalent to or, in some cases, superior to industrial sorptive materials. Results of a uranium distribution study by fission-track radiography suggest that material from weathered basic rocks is characterized by high sorptive properties for uranium also. One can assume that other radionuclides of the transuranic group will be intensely sor-bed by the residuum of weathered basic rocks. Low-temperature hyd-rothermal transformation leads to sealing fissures of the basic rocks with highly sorptive minerals, for example, smectite, chlorite, serpentine, talc, zeolite, hydroxides of Fe, Ti, Mn. The process results in contemporaneous decreasing hydraulic conductivity and increasing sorptive capacity of the rocks. HLW disposal at the radiochemical plant “Mayak” is expected to be produced in deep wells situated in basaltic rocks. The safety of disposal is based on high sorptive properties of the crust of weathering and protective capacities of volcanic rocks. This method is not expensive and may allow the disposal of HLW in the near future.
The Long-Term Stability of Becquerelite
Authors: Finch R.J. , Suksi J. , Rasilainen K. , Ewing R.C. 
Published: April 2011

AbstractUranium-series disequilibria data, in conjunction with petrographic analyses, indicate that the uranyl oxide hydrate becquerelite can persist for hundreds of thousands of years, possibly longer. Becquerelite probably forms continuously as ground water compositions permit and is resistant to U leaching by ground water. On the time scale of interest for the geologic disposal of spent UO2nuclear fuel, becquerelite is a long-lived sink for uranium in oxidizing, U and Ca-bearing ground waters. Such long-term stability also supports recent solubility experiments that indicate natural becquerelite has a lower solubility product than that determined for synthetic becquerelites.
Performance Analysis of Copper Canister Corrosion Under Oxidizing or Reducing Conditions
Authors: Worgan Karen , Apted Michael , Sjöblom Rolf 
Published: April 2011

AbstractThe finite-difference CAMEO code for modeling general corrosion of copper canisters is described. CAMEO represents the engineered barrier system and surrounding fractured host rock in 3-dimensional cylindrical coordinates. The time of containment failure is evaluated using CAMEO, as constrained by transport rates of corrodants to the canister or by transport rates of corrodant products away from the canister. Additional chemical processes explicitly modeled in CAMEO include 1) copper corrosion, and 2) kinetics of Cu(I) oxidation to Cu(II), both as a function of near-field pore water chemistry, specifically pH, Eh, and chloride concentration. The diffusional transport and sorption behavior of Cu(I) and Cu(II) are also separately incorporated.
Canister Filling Materials - Design Requirements and Evaluation of Candidate Materials
Authors: Oversby V. M. , Werme L. O. 
Published: April 2011

AbstractSKB has been evaluating a copper/steel canister for use in the disposal of spent nuclear reactor fuel. The canister consists of an outer layer of about 50 mm thickness of copper to provide corrosion resistance and an inner layer of similar size to provide structural strength. Once the canister is breached by corrosion, it is possible that the void volume inside the canister might fill with water. Water inside the canister would moderate the energy of the neutrons emitted by spontaneous fission in the fuel. If the space in the canister between and around the fuel pins is occupied by canister filling materials, the potential for criticality is avoided. We have developed a set of design requirements for canister filling material for the case where it is to be used alone, with no credit for burnup of the fuel or other measures, such as the use of neutron absorbers. Requirements were divided into three classes: essential requirements, desirable features, and undesirable features. The essential requirements are that the material fill at least 60% of the original void space, that the solubility of the filling material be less than 100 mg/l in pure water or expected repository waters at 50°C, and that the material not compact under its own weight by more than 10%. In this paper we review the reasons for these requirements, the desirable and undesirable features, and evaluate 11 candidate materials with respect to the design requirements and features. The candidate materials are glass beads, lead shot, copper spheres, sand, olivine, hematite, magnetite, crushed rock, bentonite, other clays, and concrete. Emphasis is placed on the determination of whether further work is needed to eliminate uncertainties in the evaluation of the ability of a particular filling material to be successfully used under actual conditions, and on the ability to predict the long-term performance of the material under the repository conditions.
Interactions Between Np-Doped Synroc and Boom Clay
Authors: Hart K. P. , Robinson B. J. , Payne T. E. , Van Iseghem P. , Lemmens K. 
Published: April 2011

AbstractLeaching experiments with deionised water at 70°C have been carried out to ascertain the effect of oxidising and anaerobic conditions and the presence of Boom clay on Np release from Synroc.The normalised solution leach rates of Np measured in these experiments are about a factor of 10 lower under reducing conditions than oxidising conditions and the presence of Boom clay was found not to enhance the leaching of Np from Synroc. Neptunium was found to be predominantly in the mobile fraction and was not removed from the leaching solutions significantly by filtration or ultrafiltration.
Synthesis and Characterization of A Metastable (SiC)aN4 Phase
Authors: Uslu C. , Park B. , Poker D. B. 
Published: April 2011

AbstractA metastable C-Si-N compound has been synthesized by high dose N+ implantation into polycrystalline /8-SiC (cubic phase). The thin films formed upon 100 keV implantations were characterized with respect to various ion doses and target temperatures. X-ray diffraction with a position-sensitive detector and cross-sectional transmission electron microscopy revealed that the as-implanted surfaces contained ∼0.15 jttm thick continuously-buried amorphous layers. Rutherford backscattering spectroscopy showed that the peak concentration of nitrogen saturated up to approximately 54 at. % with increasing doses, suggesting a new phase formation.
Ion irradiated polystyrene: transport and hardness Measurements
Authors: Folk II Robert H. , Luzzi David E. , Composto Russell J. , Rothmant J. Bruce 
Published: April 2011

AbstractThin films of polystyrene (PS) were modified using oxygen (0+) and helium (He+) ions and analyzed via diffusion and hardness measurements. One micron thick films were modified with 400 keV 0+ and He+ ions. The fluence was varied from 1.7 to 34.0 x 1013 ions/cm2 for both incident ions. Following irradiation, some samples were covered with a probe layer of deuterated PS, and annealed at 170°C. Using forward recoil spectrometry, the diffusion of d-PS and the PS hydrogen loss were measured as a function of incident ion species and dose. For all modified samples, d-PS diffusion was significantly retarded compared to the unmodified case. Atomic force microscopy measurements on the as-cast and irradiated PS samples suggest that the relative hardness of the 0+ modified PS was greater than that of the as-cast PS. The force-displacement curves of the modified PS displayed no hysteresis whereas the as-cast PS had a large hysteresis due to tip penetration and tip-polymer adhesion. These results indicate that ion irradiation decreases transport in PS and increases PS hardness.
UV Laser Deposition of Thin Films at 248 NM for Phase Shifting Mask Repair
Authors: Farkas Janos , Comita Paul B. , Novotny Vlad , Miller Dolores , yeng Baurui , Cohen Martin 
Published: April 2011

AbstractLaser-induced deposition of controlled quality silicon dioxide and thin metallic films was investigated at 248 nm for phase shifting mask (PSM) repair. SiOx (x-1.5-2) films were deposited from single precursors, such as triethoxyvinylsilane (TEVS), tetraallyloxysilane (TAOS), di-t-butoxy-diacetooxysilane (TBSA) with no oxidizing coreactant. A deposition rate of 0.25 A/pulse was possible at room temperature, with excellent optical properties (n-1.47, k-0.05). Metallic films were deposited from tungsten, gold, molybdenum and chromium compounds. The results showed that the optical transmission and phase-shifting properties of the deposits can be matched well to the films commonly used in phase shifting masks.
Temperature Dependent Growth of LaAIO3 Films on YBa2Cu3O7 C-Axis Films for Multilayer Structures
Authors: Hawley M.E. , Houlton R.J. , Raistrick I. A. , Garzon F.H. 
Published: April 2011

AbstractFabrication of ultra smooth films, free of micro-shorts, is essential to the development of High Temperature Superconducting (HTS) thin film devices. One such example is a SNS junction consisting of two HTS layers separated by a uniformly smooth continuous barrier material. Other schemes under consideration require multilayer structures of up to 5 - 7 epitaxially grown layers of complex oxide material. Successful fabrication of such devices necessitates understanding the epitaxial growth of polycrystalline oxide films on polycrystalline film templates. Toward this end we have developed a set of deposition parameters that produce high quality epitaxial insulating layers suitable for HTS device applications. All films in this study were grown by off-axis RF magnetron sputter deposition. LaAlO3 films were deposited over MgO grown YBa2Cu3O7 (YBCO) c-axis thin films at temperatures ranging from 200 to 700C and on virgin substrates at 600C. Atomic Force Microscopy, eddy current measurements, and x-ray diffraction techniques were used to monitor the effect of growth conditions on the resulting film crystallinity, nanostructure, and electrical properties.Ex-situ interrupted growth characterization of these materials has yielded new insight into the processes that control the growth mechanism and resulting microstructure. All films were polycrystalline. Below 600C, LaAlO3 films were not epitaxial while films grown at 650C showed some <200> orientation. The shape of the underlying YBCO film is most clearly evident for the film grown at 400C. Surface roughness depended on the appearance of crystals on the film surface. The superconducting properties of the underlying YBCO film required O2 annealing prior to deposition of the LaAlO3 layer.
Structure of Oxides Grown on Zr-20Nb Alloy
Authors: Woo O.T. , Lockwood D.J. , Lin Y.P. , Urbanic V.F. 
Published: April 2011

AbstractOxides grown on Zr-20Nb were characterized by Raman Spectroscopy (RS), X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). These oxides were steamformed at 400°C, water-formed at 360 °C and at 300 °C, and air-grown at 400°C. For the oxides grown after relatively short exposures at 360°C and at 400°C, Raman spectra revealed broad peaks at 260 and 660 cm− indicating a crystal structure with high symmetry. Comparison with reference Raman spectra of cubic (c), tetragonal (t), and monoclinic (m) ZrO2 suggested that the oxide was predominantly nearly-cubic (tetragonal with c/a ratio ≈ 1), with minor amounts of moxide. The tetragonality is found to be consistent with TEM analyses and XRD results which showed the presence of a doublet near 2θ ° 74°. The crystal structure in the short-term exposed oxides is interpreted in terms of a tetragonal distortion arising from the displacement of oxygen atoms within the cubic ZrO2 crystal structure. For oxides grown after longer periods of exposure at 300°C and at 400°C, RS and XRD indicate increased amounts of m-oxide.
Composition Dependence of The Electrical Conductivity of n-p Ceramic Composite
Authors: Jun Seok-Taek , Choi Gyeong-Man 
Published: April 2011

AbstractElectrical properties of ZnO-CuO ceramic composites with varying composition were investigated. The electrical conductivity increased with increasing CuO volume fraction between 1 mol% to 95 mol%. Impedance response showed three semicircles, indicating three resistive elements contributing to the total resistance of the composite. A new model based on the equivalent circuits was developed to explain the contribution of grain boundaries to the resistance of the composite. The change of electrical conductivity was explained by the probability change of two equivalent circuits.