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991.
It is demonstrated experimentally that in the microindentation process, elastic deformation takes place of the crystal surface region under load containing the forming imprint. A technique is proposed for determining this elastic deformation in alkali-haloid crystals. 相似文献
992.
Z. V. Golubenko A. S. Kamzin L. P. Ol’khovik M. M. Khvorov Z. I. Sizova V. P. Shabatin 《Physics of the Solid State》2002,44(9):1698-1702
Magnetization and remagnetization processes in a close-packed nanodispersed barium hexaferrite powder sample in the magnetically stable state were analyzed. Reversibility effects were discussed in terms of interparticle interaction. Judging from the magnetization curve and the parameters characterizing remagnetization irreversibility, the sample under study is a model system of small Stoner-Wohlfarth particles. 相似文献
993.
The equilibrium geometry and hyperfine interaction constants of the nearest and next-to-nearest neighbor atoms are calculated for a negatively charged silicon vacancy in the high-spin state in cubic SiC. The calculations are performed within the cluster approach in terms of the density-functional theory (DFT). It is shown that the results of calculations with the use of a 70-atom cluster are in good agreement with experimental data. A detailed consideration is given to spin polarization in the electron subsystem and the applicability of a simple LCAO model that is commonly used in the interpretation of the electron paramagnetic resonance data for semiconductors. The spin density distribution for the defect under investigation is analyzed in terms of localized orbitals. 相似文献
994.
995.
An analysis of events in the tunneling junction shows that the interaction of one-electron processes in a many-electron system may be a source of scale-invariant low-frequency fluctuations of conductivity (the interaction consists in that the quantum probability of an electron transition depends on fast random changes in the environment in the course of the transition, including the changes caused by analogous transitions). The theory relates flicker fluctuations in the tunneling conductivity to the discrete character of the spectrum of electron states and explains the nonlinearity of the noise-current characteristic observed in nanocomposites. 相似文献
996.
997.
Chemical bonding in isolated molecules and crystals of zwitterionic pentacoordinate silicon chelates
The electronic structures of a number of zwitterionic pentacoordinate silicon chelates were investigated using the results of X-ray diffraction studies and quantum-chemical calculatoins by the MPW1PW91/6-311G(d) method. The topological analysis of the electron density distribution function and the study in the framework of the natural bond orbital partitioning scheme showed that the character of chemical bonding in the axial fragments of the molecules under consideration changes from dative to three-center, four-electron as the silicon atom assumes a trigonal-bipyramidal coordination. 相似文献
998.
The electrodynamic properties of granular high-temperature superconducting media are studied. Relations for the surface resistance and impedance of a high-temperature superconducting medium are derived. The temperature and frequency dependence of the phase velocity and group velocity and depth of penetration of the electromagnetic field into the Josephson medium are calculated. The possibility of using high-temperature superconducting films as high-efficiency shields is shown. The shielding properties are improved appreciably with increase in the critical current density of the high-temperature superconducting film. The shield thickness is several microns or several fractions of a micron for a critical current density of >107 A/m2. The results obtained can be used in designing superhigh-frequency shields, microstrip lines, and other devices based on high-temperature superconducting Josephson media. 相似文献
999.
Timinskas A. Cheshunene A. Kurtinaitene M. Skominas V. 《Russian Journal of Applied Chemistry》2002,75(6):911-914
Conditions under which anodized aluminum is treated first in a dilute solution of phosphoric acid and then in a fluoroborate immersion solution in order to deposit a multilayer system of cobalt and copper in the pores in the oxide were studied. 相似文献
1000.
Using elementary graded automorphisms of polytopal algebras (essentially the coordinate rings of projective toric varieties)
polyhedral versions of the group of elementary matrices and the Steinberg and Milnor groups are defined. They coincide with
the usual K-theoretic groups in the special case when the polytope is a unit simplex and can be thought of as compact/polytopal substitutes
for the tame automorphism groups of polynomial algebras. Relative to the classical case, many new aspects have to be taken
into account. We describe these groups explicitly when the underlying polytope is 2-dimensional. Already this low-dimensional
case provides interesting classes of groups.
Received: 13 December 2001 / Revised version: 24 June 2002
The second author was supported by the Deutsche Forschungsgemeinschaft, INTAS grant 99-00817 and TMR grant ERB FMRX CT-97-0107
Mathematics Subject Classification (2000): 14L27, 14M25, 19C09, 52B20 相似文献