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Showing 1 to 14 of 14 for “"vacancy concentrations"”.
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Direct Measurement of Equilibrium Vacancy Concentrations in Dilute Aluminum - Silver Alloys
Made available in DSpace on 2014-12-10T17:57:38Z (GMT). No. of bitstreams: 1 6408348.pdf: 1697129 bytes, checksum: a6170c680934fcdaf7f0a036cbdd90ce (MD5) Previous issue date: 1964
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Equilibrium vacancy concentration measurements in solid argon
… and lattice expansion to determine equilibrium vacancy concentrations, has been applied to solid argon. The results indicate that vacancy concentrations do not exceed 0.02% even at the highest temperatures. Although the data obtained were not sufficiently precise to allow unique values to be …
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Thermal vacancies in solid helium-3
Thermal vacancy concentrations in crystals of 3He have been determined from high precision measurements of the tem3 perature dependence of the x-ray lattice parameter. Bcc He 3 was studied for molar volumes ranging from 20.3 to 24.8 cm ; mole for which the melting temperatures range from 2.36 to …
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Thermal vacancies and phase separation in bcc mixtures of helium-3 and helium-4
Thermal vacancy concentrations in crystals of 3He-4He mixtures have been determined from accurate measurements of the temperature dependence of the x-ray lattice parameter. A new x-ray diffractometer-position sensitive detector system is used to make measurements of the absolute lattice parameter …
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X-ray diffraction study of compressed solid argon and krypton
… and solid krypton and to measure changes in vacancy concentrations along quasi-isochores for both these substances. The uncertainty of the lattice parameters obtained along melting was estimated to be 27 ppm. These measurements are believed to be the most precise melting line density data …
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Hydrogen effects on the point defect spectrum in Fe-C alloys
… functional theory methods, the stability and concentrations of the point defect clusters present in metastable Fe-C-H alloys with vacancies. The defect spectrum is found to be strongly dependent on the local vacancy concentration, and for low hydrogen levels sharp highly non-linear changes in …
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Effects of vacancies and electron temperature on the electron phonon coupling in cubic silicon carbide and their connection to the inelastic thermal spike
… of extending those calculations to lower vacancy concentrations using a rule-of-mixtures approach. </p><p>The electron-temperature-dependent couplings were implemented in the Two-Temperature Model (TTM), which was used to model the evolution of electron and phonon temperatures following …
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X-ray diffraction study of the high-density phases of solid 4He
… to the diffuse intensity. Estimates of vacancy concentrations in the fcc phase, as measured from lattice parameter shifts, greatly extend the density range over which these
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Electronic correlations in Lix̳ CoO₂
… calculations indicate that for dilute Li vacancy concentrations (ie x > 0.95), the vacancy potential binds its hole and forms an impurity state which leads to a Mott insulator. We argue that the first-order transition is due to a decomposition of the impurity band, and is perhaps the only …
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Atomic scale diffusion in complex systems from first principles
… tolerant alloys. We accurately model the vacancy metastable states observed in HCP Zr and for the first time examine the effect of these states on solute transport. Our results show that Sn and Al diffuse via vacancy mediated mechanism while Cr, Fe, Be and Ni diffuse via the interstitial …
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Role of Vacancies and Electrochemical Applications of Facet-Controlled Synthetic Superlattice Nanomaterials
… be characterized. In this context, types and concentrations of vacancies were identified, and the correlation between types and concentration of vacancies and transient photocurrent properties were investigated. The first section of the thesis focuses on the synthesis of high performance …
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Modeling microstructural effects of deformation resistance and thermal conductivity
… of refractory carbides at realistic carbon vacancy concentrations. This is a long-standing problem which even the most recent review article on the subject give what I now believe is the wrong estimate. Second, ideal strengths are calculated for Ar,Cu,SiC crystals using both lattice and …
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Modeling of mechanisms affecting the growth and breakdown of iron sulfide films
… we resolve the influence of magnetic and vacancy ordering transitions on ionic migration barriers and diffusivity of pyrrhotite, Fe₁-xS. Specifically, we identify that the ionic migration barrier is unaffected by the local vacancy configuration in different pyrrhotite polytypes, but is …
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Chemomechanical modeling of hydrogen-induced degradation at high temperatures
… rupture in structural materials by increasing vacancy concentrations and enhancing dislocation climb. The last contribution of this dissertation is a physically based creep constitutive model rooted in the thermodynamics of hydrogen trapping at vacancies, providing a predictive framework for …