Temat: 61.72.Bb - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Calculation of Lattice Relaxation in Some Substitutional Alloys Using a Green Function
Autorzy:: Das, S. K.
Datta Roy (Paul), S.
Tematy:: 61.72.Bb
61.82.Bg; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1995663.pdf Link otwiera się w nowym oknie
Opis:: In this paper we calculate nearest neighbour relaxation in some dilute substitutional alloys using a lattice static Green function and the Morse potential function. Distant neighbour relaxation is calculated by invoking a continuum approximation. The potential parameters for the unlike interactions are calculated using simple interpolation formulae. Using the above relaxation, we calculate volume changes in the above alloys. It is observed that the simple model predicts values which are in reasonably good agreement with the experimental values in all cases. The calculated values are also compared with those obtained from the Vegard law. For Au-Ag alloy, our model reproduces both the correct sign and the magnitude of the volume change, whereas the Vegard law cannot even give the sign of the volume change. This shows the inherent strength of the present model.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: A Green Function Estimation of Correction to Vegards Law for isovalent Substitutional Defects in Alkali Halide Crystals
Autorzy:: Datta Roy (Paul), S.
Das, S. K.
Tematy:: 61.72.Bb
61.82.Bg; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2013286.pdf Link otwiera się w nowym oknie
Opis:: A Green function method is developed for estimation of lattice parameter r(χ) of an AX-BX solid solution over entire composition range (χ=0 to 1). The r(χ) obtained in the present method is different from the value r$\text{}_{V}$(χ) suggested by Vegard's law. We estimated the deviation from Vegard's law, r(χ)-r$\text{}_{V}$(χ), over entire composition range for isovalent substitutional defect in alkali halide crystals. When compared to X-ray diffraction measurements, we find that the deviation is in correct direction, variation of r(χ) with χ is consistent with experiment and the overall agreement is fairly good considering the accuracy of the experiment.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Evolution of Matrix-Twin Interfaces of (101̅2) Twin in Magnesium
Autorzy:: Ostapovets, A.
Serra, A.
Tematy:: 61.72.Bb
61.72.Mm
62.20.F-; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1402119.pdf Link otwiera się w nowym oknie
Opis:: Recently, the presence of basal-prismatic interfaces in hexagonal close packed metals became subject of intensive investigation. We model the {101̅2} twin in magnesium bounded by two types of boundaries, i.e. {101̅2} interface and basal-prismatic facets. The migration of all boundary types is mediated by the motion of interfacial disconnections. It was shown that basal-prismatic interfaces play an important role in twin growth. The lengths of basal-prismatic facets remain constant during migration independently of the applied strain. In contrast, the {101̅2} interfaces increase their lengths during growth.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Mould walls inclination and dendritic morphology of CMSX-4 blades airfoils
Autorzy:: Krawczyk, J.
Bogdanowicz, W.
Sieniawski, J.
Kubiak, K.
Tematy:: 68.70.+w
61.66.Dk
61.72.Bb; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1075667.pdf Link otwiera się w nowym oknie
Opis:: The airfoils of single-crystalline turbine blades were studied. The blades made of industrial CMSX-4 superalloy were obtained by the Bridgman technique. Five different withdrawal rates (1-5 mm/min) were used. Series of as-cast samples were prepared by cutting the airfoils at different distances from the blade root. The metallographic sections, prepared for each cutting planes, were subjected to scanning electron microscopy observations and Laue diffraction studies. Macrostructure images of whole area of airfoil cross-sections were obtained by stitching several obtained SEM images. Morphology of dendrites in different area of cross-sections were analysed. The crystal orientation of each sample were determined by analysis of Laue pattern. It was found that the morphology of dendrites changes in the area, where the dendrite growth is limited by inclined mould walls.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 5.

Tytuł:: Paramagnetic State of Hydrogen-Passivated Double-Donor Centers in Silicon
Autorzy:: Gregorkiewicz, T.
Zevenbergen, I. S.
Martynov, Yu. V.
Ammerlaan, C. A. J.
Tematy:: 76.30.Lh
61.72.Bb
76.70.Dx; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1933751.pdf Link otwiera się w nowym oknie
Opis:: Hydrogenation of two double donor centers in silicon - substitutional sulfur and thermal donor - is studied by electron paramagnetic resonance and electron-nuclear double resonance. For both centers the existence of a new paramagnetic S = 1/2 state identified as the neutral charge state of the double donor passivated with a single hydrogen atom is concluded. The microscopic structure of such complexes is discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Phase Field Modeling of the $Zn_{1-x}Cd_xO$ Solid Solutions
Autorzy:: Shtepliuk, I.
Podolskaia, N.
Lashkarev, G.
Tematy:: 64.60.My
05.70.Ln
61.72.Bb
61.72.Mm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1375728.pdf Link otwiera się w nowym oknie
Opis:: The analysis of spinodal decomposition in the $Zn_{1-x}Cd_xO$ ternary alloy was carried out by means of the nonlinear Cahn-Hilliard equation. Interaction parameter as a function of composition x was provided by valence force field simulations and was used in this analysis. The morphological patterns for the ternary alloys with different Cd content (x=5, 10, 50%) were experimentally obtained using the semi-implicit Fourier-spectral method. The simulated microstructure evolution $Zn_{0.95}Cd_{0.05}O$ demonstrates that the microstructure having a form of bicontinuous worm-like network is evolved with the progress of aging. An effect of the phase-field mobility and the gradient energy on the microstructure evolution of the $Zn_{1-x}Cd_xO$ alloys is discussed. It was found that the higher driving force for the decomposition in the higher Cd content film results in a higher decomposition rate revealed by the simulations. The temporal evolution of the simulated $Zn_{0.95}Cd_{0.05}O$ microstructure is in good agreement with experimental results, which have been obtained for this solid solution.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 7.

Tytuł:: Defects and Defect Reactions in Semiconductor Nitrides
Autorzy:: Van de Walle, C. G.
Neugebauer, J.
Stampfl, C.
McCluskey, M. D.
Johnson, N. M.
Tematy:: 61.72.Bb
61.72.Ji
61.82.Fk
71.55.Eq; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2011140.pdf Link otwiera się w nowym oknie
Opis:: We report a comprehensive investigation of native point defects and impurities in GaN, AlN, and AlGaN alloys, with the goal of understanding doping limitations in nitride semiconductors. Unintentional incorporation of impurities (mainly oxygen) explains the tendency of nitride semiconductors to exhibit n-type conductivity. Silicon is the n-type dopant of choice; it remains shallow in AlGaN up to high Al content, while oxygen undergoes a DX transition. Experimental evidence for DX centers will be discussed. In p-type material, Mg doping is hindered by an increase in ionization energy with increasing Al content in AlGaN, and by nitrogen vacancies acting as compensating centers. Complex formation between magnesium and oxygen and between magnesium and nitrogen vacancies will be discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: An ab initio Study of a Model of Single Wall GaN Nanotubes with Oxygen and Zinc as Impurities: Structural and Electronic Properties
Autorzy:: Rezouali, K.
Belkhir, M.
Tematy:: 61.46.Fg
61.72.Bb
73.61.Ey
73.61.Wp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1813497.pdf Link otwiera się w nowym oknie
Opis:: We report a comprehensive theoretical study of structural and electronic properties of substitutional oxygen and zinc contaminations in a model of single wall GaN nanotubes by means of ab initio supercell calculations. Our investigation yields many interesting results. The following ones deserve to be developed. Oxygen forms a shallow donor in the single wall GaN nanotubes as in bulk GaN polytypes. Its ionization energy is deeper than its counterpart in the bulk wurtzite GaN, so it can be a suitable n-type dopant in high temperature applications. Zinc is a relatively shallow acceptor at gallium site. It behaves as charge carrier trap at nitrogen site. The site preference of zinc impurity depends on the stoichiometry. Zinc at gallium site has small ionization energy, thus it would be an efficient p-dopant in GaN nanotubes unlike in bulk GaN polytypes.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Theoretical Studies of ESR Parameters and Local Lattice Structure of the Vanadate-Lithium-Borate Glasses
Autorzy:: Feng, W.
Zhao, M.
Li, T.
Zhang, X.
Xue, J.
Tematy:: 71.70.Ch
75.10.Dg
61.72.Bb
76.30.Fc; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1419845.pdf Link otwiera się w nowym oknie
Opis:: Electron spin resonance spectral parameters of $V^{4+}$ ions in vanadate-lithium-borate glasses have been calculated by the crystal-field theory. The theoretical results are $g_{∥ }$ = 1.940, $g_{⊥}$ = 1.983 and $A_{∥ } = -175 \times 10^{-4} cm^{-1},$ $A_{⊥} = -65 \times 10^{-4} cm^{-1}$ which are good agreement with the experimental values ($g_{∥ }$ = 1.939(3), $g_{⊥}$ = 1.998(3) and $A_{∥ } = (170.6-176.4) \times 10^{-4} cm^{-1},$ $A_{⊥} = (61.3-71.4) \times 10^{-4} cm^{-1}$). In addition, the bond lengths of the local lattice structure are, respectively, $R_{∥ }$ = 1.5 Å and $R_{⊥}$ = 1.95 Å which have been shown to have a compressed tetrahedral geometry along the $C_4$ axis.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Theoretical Explanations of the Optical Band Positions and Local Structure for $Cu^{2+}$ Centers in $ZnO-Bi_{2}O_{3}-B_{2}O_{3}-CuO$ Glasses
Autorzy:: Yuan, M.
Tematy:: 61.72.Bb
75.10.Dg
76.30.-v
76.30.Fc; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1377767.pdf Link otwiera się w nowym oknie
Opis:: The local structure, two optical band positions and three electronic spin resonance parameters for $Cu^{2+}$ centers at the tetragonally-distorted octahedral sites in $ZnO-Bi_2O_3-B_2O_3-CuO$ glasses are calculated from the high-order perturbation method based on the two-spin-orbit-parameter model, where the contributions from both the spin-orbit coupling parameters of central $d^{n}$ ion and ligand ion are included. The theoretical results are in good agreement with the experimental values. The calculations show that the high-order perturbation method based on the two-spin-orbit-parameter model is effective in the explanations of optical spectra, electronic spin resonance parameters and local distortion structure for $d^{9}$ ions in glasses.
Dostawca treści:: Biblioteka Nauki

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