bluuebunny/crossref_metadata_2025_split huggingface dataset:
STRAIN AND REORDERING IN CaF2/Si(lll) EPITAXY
Authors: HASHIMOTO SHIN , SCHOWALTER L.J. , R.W.FATHAUER-a2  , GIBSON W.M. 
Published: March 2011

AbstractStrains in CaF2 films, grown by molecular beam epitaxy at 700ºC on Si(lll) subsrates, have been measured by MeV 4He+ ion channeling. For CaF2 films thinner than 200nm, the strain parallel to the (111) plane is found to be tensile. No strain is observed for films thicker than 200nm. The observed tensile strain cannot be explained by a simple pseudomorphic growth model because the larger lattice constant of CaF2 relative to Si should result in a compressive misfit strain. The tensile strain is an indication of the relaxation of the compressive misfit strain at the growth temperature due to nucleation of interfacial defects. If these defects are not annealed out as the substrate temperature is lowered after growth, the tensile strain can result because of the larger thermal contraction of CaF2 compared to Si. The final film quality near the interface improves as the film thickness is increased. This indicates that reordering of interfacial disorder is caused by the strain energy accumulated during the cooling process.
EPITAXIAL GROWTH OF ZIRCONIA AND YTTRIA STABILIZED ZIRCONIA FILMS ON SAPPHIRE SUBSTRATES BY REACTIVE SPUTTERING
Authors: KONUSHI F. , DOI T. , MATSUNAGA H. , KAKIHARA Y. , KOBA M. , AWANE K. , NAKAMURA I. 
Published: March 2011

AbstractEpitaxial single crystal growth of zirconia (ZrO2) and yttria stabilized zirconia (ZrO2 ·Y2O3) films on sapphire substrates was achieved for the first time by using reactive sputtering. And the relations of crystallographic orientations between the epitaxial films and sapphire substrates was determined. Yttria stabilized zirconia films seem to offer hiah quality SOI substrates, since the crystal structure of ZrO2·Y2O3 is cubic fluorite and its lattice constant is closely matched to those of semiconductors such as Si and GaAs.
Effects of Se implantation on the compositional disordering of GaAs-AlAs superlattices
Authors: NAKAMURA T. , KOMIYA S. , INATA T. , MUTO S. , HIYAMIZU S. 
Published: March 2011

AbstractThe LO phonon frequency evaluated from Raman spectra identifies two compositional disordering mechanisms in GaAs-AlAs superlattices. For a high Se dose, the LO phonons of the Al0.5Ga0.5As alloy are observed from the asimplanted samples. That means the compositional disordering occurred just by Se implantation. The probable mechanism for this disordering is the implantation of Ga atoms into the AlAs layer and of Al atoms into the GaAs layer. The superlattices implanted at a low dose are disordered by the subsequent annealing. The mechanism is the enhanced interdiffusion of both Ga and Al atoms between the GaAs and AlAs layers by Se thermal diffusion.
EQUALLY STRAINED Si/SiGe SUPERLATTICES ON Si SUBSTRATES
Authors: KASPER E. , HERZOG H.-J. , H.DAEMBKES-a1  , ABSTREITER G. 
Published: March 2011

AbstractGrowth of Si/SiGe superlattices on Si substrates by molecular beam epitaxy (MBE) is described. Strain symmetrization in the superlattice is achieved with an incommensurate SiGe buffer layer. The concept of strainsymmetrization is explained and properties of buffer and strained layer superlattices are investigated. A twodimensional electron gas with enhanced room temperature mobility and folded phonon modes within the reduced onedimensional Brillouin zone are observed. An n-channel Si/SiGe MODFET demonstrates the device applications of this material concept.
ELASTIC PROPERTIES OF METAL SUPERLATTICES
Authors: JANKOWSKI A.F. , TSAKALAKOS T. 
Published: March 2011

AbstractThe elastic properties of modulated structure materials are presented. An enhanced modulus effect has been observed in several composition modulated thin film systems containing short wavelength modulations.8-10nm. The foils were produced by vapor deposition using two or three source evaporator. As compared with homogeneous foils of the same average composition, the modulated foils exhibited an appreciable increase (up to 300%) in modulus. The dependence of various moduli on the modulation parameters (wavelength, composition and amplitude) are described. The plastic behavior, breaking and microhardness of these foils are also presented as a function of the modulation parameters. Current theories based on electronic and strain effects on the elastic constants of metals are also presented to explain the origin of the supermodulus effect.
UPPER CRITICAL FIELD OF Mo-Ni HETEROSTRUCTURES
Authors: UHER CTIRAD , WATSON W.J. , COHN J.L. , SCHULLER IVAN K. 
Published: March 2011

AbstractUpper critical field and its anisotropy have been measured on two very short wavelength Mo-Ni heterostructures of different degrees of perfection, λ = 13.8Å (disordered structure) and X = 16.6Å (layered structure). In both cases the parallel critical field has an unexpected temperature dependence, a large and temperature dependent anisotropy, and over 60% enhancement over the Clogston-Chandrasekhar limit. Data are fit to the Werthamer-Helfand-Hohenberg theory and the spin-orbit scattering times are found to be 1.79 × 10−13 sec and 2 × 10−13 sec, respectively.
PHOTOLUMINESCENCE AND ELECTRICAL PROPERTIES OF EPITAXIAL GaAs GROWN BY CLOSE SPACE VAPOR TRANSPORT
Authors: MIMILA J. , BOURGOIN J.C. , LEGROS R. , HUBER A 
Published: March 2011

AbstractThe growth of epitaxial GaAs layers on semi-insulating substrates, using high purity GaAs as source material has been obtained by the so-called lose Space Vapor Transport technique. The thermodynamical conditions of the growth, the effect of the growth parameters : source and substrate temperatures, pressure of transporting gas (water vapor) on the growth rate were investigated. Then, the variations of the optical, electrical and deep levels properties of the layers were studied as a function of the growth parameters in order to determine the values of these parameters for which the layers present the best electronic properties. Here, we describe i) the evolution of the photoluminescence spectra versus the substrate and source temperatures, the water vapor pressure being kept constant at its best value; ii) a secondary ion mass spectroscopy analysis of the main impurities contained in the layers. The results demonstrate that the layers are homogeneously Si and S doped, the doping being slightly compensated, the layer-substrate interface is clean and the PL is characteristic of a defect free material.
SOLID PHASE EPITAXIAL GROWTH OF Ge ON GaAs
Authors: Palmstrom C.J. , Galvin G.J. , Schwarz S.A. , Cooman B.C. De , Mayer J.W. 
Published: March 2011

AbstractSolid phase epitaxial growth of electron beam evaporated Ge layers on unheated GaAs has been demonstrated. The amorphous Ge layers grow epitaxially on the GaAs surface during anneals at 400°C. A technique for growing these epitaxial layers without the need for in-situ heat treatment of the GaAs prior to Ge deposition is described.
ANTIPHASE DOMAIN FREE EPITAXIAL GROWTH OF GaAs ON (100)Ge
Authors: Shinoda Y. , Ohmachi Y. 
Published: March 2011

AbstractHigh-quality single domain GaAs epitaxial layers were successfully grown on (100)Ge substrates. Growth was carried out using conventional metalorganic chemical vapor deposition at atmospheric pressure. Antiphase domain free GaAs epitaxial layers were obtained by thermal etching of the Ge surface just prior to growth. Mosaic surface morphology and antiphase boundaries characteristic of domain structures were completely absent in epi-layers following thermal etching. Photoluminescence revealed that domain free epi-layers exhibited characteristics comparable to those of GaAs homoepitaxial layers.
Rapidly Solidified Alloys for Permanent Magnets
Authors: Hadjipanayis G.C. 
Published: March 2011

ABSTRACTThe magnetic and structural properties of melt-spun Fe-R-B alloys are reviewed. The hard magnetic properties of these alloys are attributed to the presence of a highly anisotropic tetragonal phase Fe14R2B which in the case of ribbons occurs in very fine grains. The interachoot of domain walls with this fine microstructure leads to the observed high coercivities. The effects of partial substitution of iron, rare-earth and boron on the formation of Fe14R2B and on its magnetic properties are also discussed.
Magnetic Effect on the Phase Equilibria of FCC(Fe,Ni) Alloys at Low Temperatures
Authors: Lin Jen-Chwen , Chuang Ying-Yu , Chang Y. Austin 
Published: March 2011

ABSTRACTPhase stabilities of iron alloys at low temperatures are strongly infuenced by magnetic effect. The appearance of certain type of equilibria is often due entirely to magnetic contribution to the Gibbs energy of the pertinent phase. The appearance of the stable and metastable equilibria in fcc(Fe,Ni) alloys are discussed in terms of the magnetic interaction.
Tensile and Creep Properties of Rapidly Solidified Titanium Alloys Containing Complex Matrices and Fine Dispersoids
Authors: Gigliotti M.F.X. , Rowe R.G. , Wasielewski G.E. , Scarr G.K. , Williams J.C. 
Published: March 2011

ABSTRACTTitanium alloys containing alpha matrices with various rare earth compound dispersions were prepared by melt extraction. The melt extracted material was HIPped, extruded, and thermally exposed to yield various microstructures including transformed beta and equiaxed alpha. Tensile and creep tests were conducted on material in the different microstructural conditions. Trends in mechanical behavior as a function of alloy chemistry and process history are discussed. The alloys with a transformed beta microstructure had superior creep resistance. Alloys containing dispersoids had better tensile ductilities compared with those which did not contain a dispersoid.Portions of this work were carried out under Air Force Contract F33615-83-C-5034.
Mechanical Properties of Rapidly Solidified High Carbon Iron Base Alloys
Authors: Burchards D. , Kainer K.U. , Mordike B.L. 
Published: March 2011

ABSTRACTHigh carbon content iron base alloys (2–4 wt%) with various alloying additions,eg., Cr, Ni, Si or Te were produced in powder form by water atomisation. Depending on the alloying addition the powder particles solidify, microcrystalline with either dendritic or cellular microstructures with supersaturated solid solution and eutectic. The proportion of carbide is dependent on the composition and atomizing conditions. The powder, after suitable preparation, was consolidated by extrusion or hot isostatic pressing. The consolidation behaviour of the powders is influenced by the composition and particle size distribution. The microstructures and hardness values of the powder in the as quenched state are compared with those of the consolidated state with particular emphasis on the thermal stability. The mechanical properties of extruded powders are compared with those for hot isostatically pressed.
Structural Relaxation in Fe-B Glasses
Authors: Altounian Z. , Strom-Olsen J.O. , Olivier N. 
Published: March 2011

ABSTRACTWe present results on structural relaxation in Fe-B glasses. Relaxation effects were studied through measurements of the Curie temperature (Tc) of the glasses annealed at different temperatures (Ta). We observe a monotonic increase in Tc with Ta in all alloys due to irreversible structural relaxation. This increase continues till the start of surface/ bulk crystallization. The observed decrease in Tc upon further annealing is attributed to the strain introduced in the partially glassy system. We see no evidence for reversible structural relaxation in Fe-B glasses.
New Optical Transition at Thermal Donors in Silicon
Authors: Weber J. , Queisser H. J. 
Published: March 2011

ABSTRACTWe detect new luminescence lines in Czochralski-grown silicon after prolonged heat treatments at 450°C. The properties of the new optical transition are well explained by a thermal donor-free hole recombination. From the IR-absorption spectra measured on the same samples, we have evidence for an inhomogeneous distribution of the thermal donors. The spatial fluctuations of the thermal donors appear to be necessary for the new luminescence spectrum to emerge.
Nitrogen-Carbon Interactions in Optical Defects in Silicon
Authors: Dörnen A. , Sauer R. , Pensl G. 
Published: March 2011

ABSTRACTWe report five photoluminescence lines N1 through N5 in silicon which emerge after sequential nitrogen and carbon implantation. Studied is in particular the 0.7456 eV (N1) electronic-vibronic spectrum. Single nitrogen and carbon atoms in the defect are identified by isotope shifts of the no-phonon transition and of a local mode satellite with vibration quantum energy ħω= 122.9 meV. Uniaxial stress or Zeeman measurements yield monoclinic I (C1h) or trigonal (C3v) symmetry, respectively, of the optical defect. Comparing the energy of the local mode and its isotope effects with recent literature data on the nitrogen 963 cm−1 IR vibrational absorption line we discuss a defect model involving a substitutional nitrogen atom modified by an interstitial carbon atom.
Immersion and Leach Tests on Solidified Decontamination Wastes From Dresden Unit 1
Authors: Barletta Robert E. , Adams Jay W. , Davis Richard E. 
Published: March 2011

ABSTRACTIn order to provide technical support to the NRC, Brookhaven National Laboratory has performed leach tests and immersion tests using organic liquids and organic saturated water of concentrated decontamination waste solidified using a vinyl ester-styrene binder.The leach tests measured the release of Fe, Ni, and Co from these forms in deionized water, groundwater, and seawater. After 64 days, the mean fraction released normalized by V/S for iron was 5.1 ± 1.9 × 10−3 cm in deionized water, 7.1 ± 1.1 × 10−3 cm in groundwater, and 9.0 ± 3.2 × 10−3 cm in seawater. For nickel, 64 day release rates observed were 4.6 ± 1.6 × 10−3 cm, 4.6 ± 1.0 × 10−3 cm, and 5.9 ± 0.6 × 10−3 cm in deionized water, groundwater, and seawater, respectively. After 50 days, the 59 Fe release rates were 5.9 ± 0.7 × 10−3, 4.8 ± 2.4 × 10−3, and 2.8 ± 1.0 × 10−3 cm in deionized water, groundwater, and seawater, respectively. For 60Co, the 50 day releases in the three respective leaching media were 6.0 ± 1.7 × 10−3 cm, 6.8 ± 1.0 × 10−3 cm, and 2.3 ± 0.2 × 10−3 cm.Immersion tests of waste forms prepared at a solidification demonstration held at the Dresden Nuclear Power Station were conducted in toluene, xylene, and water saturated with toluene and xylene. During immersion of samples in the pure organics, large changes in sample volume and weight were observed. Total weight changes of 9.6 ± 0.3% and 21.6 ± 0.7% were observed after 839 hours of immersion in xylene and toluene, respectively. Air drying of the samples led to an overall weight loss of 23.5 ± 0.7% for xylene and 35.6 ± 0.6% for toluene. Qualitatively, similar changes were observed for immersion tests using organic saturated water. Severe sample deterioration was observed in this case, however. The cause of this deterioration is not known.
Site Characterization for Field Radionuclide Migration Studies in Climax Granite
Authors: Isherwood Dana , Raber Ellen , Stone Randolph 
Published: March 2011

ABSTRACTRadionuclide migration experiments in fractured granite at the Climax Stock, Nevada Test Site, are needed to compare field and laboratory measured retardation factors to determine whether laboratory studies accurately reflect in situ conditions. Initial field activities have concentrated on hydrological investigations to determine whether the fractures in Climax granite are suitable for migration experiments. A critical question was whether we could isolate a single vertical fracture between two boreholes and establish flow along that fracture from an upper to a lower borehole. Of the ten fractures tested, one fracture would not take water at pressures up to 200 psig for 24 hours. Several fractures were so permeable they accepted water at a rate which exceeded the pumping capacity of the equipment. Other fractures failed to show a connection between the two boreholes. In two fractures, we were able to establish a circulating system with up to 95 percent of the injected water being recovered. Constant pressure injection tests were conducted. Intrinsic permeabilities of 33 and 75 (μm)2 were estimated using a radial nonsteady flow model. These values correspond to effective fracture apertures of 20 and 30 μm respectively. Concurrent with the hydraulic testing activities is a study of the Climax ground-water chemistry. Our analyses show the natural water to be very different in composition from the granite equilibrated water used in laboratory sorption studies. This paper includes the results of the hydrogeological and geochemical investigations, and describes the overall experimental design plans for the radionuclide migration experiments.
Predicting Pu Concentrations in Solutions Contacting Geologic Materials
Authors: Strickert Richard G. , Rai Dhanpat 
Published: March 2011

ABSTRACTKnowledge of Pu solid phases present in nuclear wastes is important for predicting the geochemical behavior of Pu. Thermodynamic data and experimental measurements using discrete Pu compounds, Pu-doped borosilicate glasses (simulating a high-level waste form), and Pu contaminated sediments suggest that PuO2(c) is very stable and is expected to be present in the repository. The solubility of the stable phase, such as PuO2(c), can be used to predict the maximum Pu concentration in solutions for long-term safety assessment of nuclear waste repositories.
A Natural Analogue for Storage of Radwaste in Crystalline Rocks
Authors: Brookins Douglas G. , Abashian Mark S. , Cohen Lewis H. , Wollenberg Harold A. 
Published: March 2011

ABSTRACTThe Bryan-Eldora stock (Colorado) intruded the Precambrian Idaho Springs Formation metamorphic rocks 58 million years ago. Geochronologic-geochemical work by Hart et al. (1) has demonstrated that the heat from the cooling intrusive rocks was sufficient to affect mineral isotopic systematics up to 2,000 m. from the contact, and the nature of these isotopic perturbations can be explained by a simple diffusion model in turn based on various heat flow models. Our new studies are focused on elemental exchange between stock and intruded rock as a function of distance from the contact; the assumption is made that the stock is a very large, high heat source analogous to a waste form emplaced in the metamorphic rocks without benefit of canister or engineered backfill. Data for U, Th and the REE indicate actinide and lanthanide immobility except perhaps in the 0–2m. contact zone where some infiltration of the country rocks by stock-derived fluids occurred. Beyond 4 m. no stock-derived U, Th, REE or *Pb are noted. Further, whole rock Rb-Sr and stable 0 isotopic data indicate conductive cooling as opposed to convective, water-induced cooling. The intruded rocks possess low porosity and permeability; this helped prevent elemental migration during the 105 − 106 years of stock crystallization. The petrographic and geochemical studies show that the Idaho Springs (or equivalent) metamorhpic rocks are well suited for radwaste storage.
Diffusion of Neptuiyl(V)- and Pertechnetate Ions in Marine Sediments
Authors: Schreiner F. , Fried S. , Friedman A. 
Published: March 2011

ABSTRACTThe diffusion of the 235NpO2+ and 95m TCo4− -ions has been measured directly in sample cylinders of two different sediments from the floor of the deep sea. In smectiterich sediment not shielded from contact with atmospheric oxygen the following values were obtained for the effective diffusion coefficients of neptunyl- and pertechnetateions, respectively: Deff(NpO2+) = 1.5 × 10−12 m2 s−1 and Deff(TcO4−) = 3.2 × 10−10 m2 s−1. Under anoxic conditions in sediment with known reducing properties, the pertechnetate ion appears to undergo slow reduction and the effective diffusion coefficient of the reduced species of Deff(Tc,red)= 1.1 × 1014 m2 s−1 reflects a substantial decrease of the mobility of the lower-valent technetium.
Mechanisms of Dissolution of Radioactive Waste Storage Glasses and Caesium Migration From a Granite Repository
Authors: Chapman Neil A. , Mckinley Ian G. , Savage David , West Julia M. 
Published: March 2011

ABSTRACTExperimental and theoretical data are used to compare the effect of three possible leach mechanisms for borosilicate glass waste buried in a granite host-rock on the release and subsequent migration of 135Cs. Protracted release episodes and variations of up to an order of magnitude in groundwater transport times and five orders in output concentrations are possible.
Evaluation of Ceramic Materials to Immobilize ICPP Calcines
Authors: Staples B. A. , Cole H. S. , Mittl J. C. 
Published: March 2011

ABSTRACTVarious ceramic materials as well as Formula 127 glass have been developed to immobilize ICPP zirconia calcine. Tailored, titanate and matrix encapsulated ceramics were prepared by cold pressing and sintering reactants, while glass-ceramics were prepared by melting in a manner similar to that of preparing the glass. X-ray diffraction techniques were used to determine the presence of radionuclide and calcine matrix element host phases in each ceramic material. The aqueous leachability, practical loading capacity and the incorporation of waste elements into host phases was investigated and compared to those of Formula 127 glass through application of the Soxhlet and MCC-1 static leach tests. Potential process requirements for each material were evaluated based on the number of steps needed for laboratory-scale preparation.
Reference Laboratory Testing For Backfill
Authors: Chung Riley M. , Yokel Felix Y. 
Published: March 2011

ABSTRACTRelatively high magnitude of swelling and low hydraulic conductivity are two of the performance requirements for the backfill placed around the radioactive waste package for the underground nuclear waste storage scheme. Some studies have been conducted in U.S. national laboratories and in other countries where the candidate backfill materials were tested under many different conditions to determine the expected range of these properties. This paper briefly examines the variables that were found to be significant in the evaluation of swelling and hydraulic conductivity and special emphasis is placed on the compaction method, compaction effort, and the moisture content at the time of compaction, which do not receive much consideration in ongoing test programs.