Materials Literature
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We use the dynamical mean-field method to study a model of electrons Jahn-Teller coupled to localized classical oscillators and ferromagnetically coupled to ``core spins.'' The model, we argue, contains the essential physics of the ``colossal magnetoresistance'' manganites ${\mathrm{Re}}_{1\mathrm{\ensuremath{-}}\math…
A series of diamond films have been grown, all at Tsub=1110 K and atomic H concentrations [H]=3×10−10 mol/cm3. The acetylene and methyl radical concentrations at the substrate surface were varied independently by factors of up to 4 and 10, respectively, by adjusting the pressure and the input methane concentration, an…
In this paper we present a molecular dynamics calculation of the Frank elastic constants of a nematic liquid crystal. We study two well-known variants of the Gay–Berne potential, and determine the elastic constants by measuring orientational fluctuations as a function of wave vector, using reasonably large system size…
We report generalized gradient approximation (GGA) cohesive energies for 3d metals. The problem of obtaining atomic reference energies in density-functional theory is considered. The effect of going to nonspherical atomic charge distributions is much larger at the GGA than at the local-density approximation (LDA) leve…
A ${\mathrm{VO}}_{2}$ film was grown on a sapphire(0001) substrate using pulsed laser deposition. The film showed a first-order metal-insulator (MI) transition and its dc conductivity started to increase drastically near 68 \ifmmode^\circ\else\textdegree\fi{}C and changed by three orders of magnitude. Mid-infrared tra…
We have studied transition-metal 3d-oxygen 2p lattice models, where full degeneracy of transition-metal 3d and oxygen 2p orbitals and on-site Coulomb and exchange interactions between 3d electrons are taken into account, by means of a spin- and orbital-unrestricted Hartree-Fock (HF) approximation. The electronic-struc…
Nanocomposites are prepared by a simple technique of emulsion polymerization using MMA monomer and Na+-montmorillonite. The products are purified by hot toluene extraction and characterized by FT-IR, X-ray diffraction, TGA, DSC, and tensile testing. The structural investigation confirms that the products are intercala…
Total energies of cubic boron nitride (c-BN) (001) surfaces are systematically studied for various reconstructed configurations by the local density-functional approach with ultrasoft pseudopotentials. Stable phases as a function of nitrogen chemical potential are predicted theoretically. We examine the validity of th…
The electronic structure of the perovskite ${\mathrm{LaCoO}}_{3}$ for different spin states of Co ions was calculated in the local-density approximation LDA+U approach. The ground state is found to be a nonmagnetic insulator with Co ions in a low-spin state. Somewhat higher in energy, we find two intermediate-spin sta…
We present a theoretical analysis of the band-edge exciton structure in nanometer-size crystallites of direct semiconductors with a cubic lattice structure or a hexagonal lattice structure which can be described within the framework of a quasicubic model. The lowest energy exciton, eightfold degenerate in spherically…
The traditional theory of many-electron atoms and ions is based on the coefficients of fractional parentage and matrix elements of tensorial operators, composed of unit tensors. The calculation of spin-angular coefficients of radial integrals appearing in the expressions of matrix elements of arbitrary physical operat…
During March 1986-February 1987 the epipelic algal flora at 4 sites of the Samboromb6n River was investigated. A total of 137 species were determined. Diatoms and cyanophytes were the most important algae. The maximum density and species richness peaks were observed during autumn and winter. Diversity increased from t…
Control of selectivity is a dominant issue for both partial and total oxidation of hydrocarbons. This chapter provides a critical overview of various factors that affect selectivity. It is suggested that both kinetic and thermodynamic aspects are important in determining selectivity in oxidation, and that selectivity…
For the orthorhombic intermetallic semiconductor Al$_2$Ru, the bandstructure, valence charge density, zone center optical phonon frequencies, and Born effective charge and electronic dielectric tensors are calculated using variational density functional perturbation theory with {\em ab initio} pseudopotentials and a p…
This edition has been greatly enlarged and updated to provide both scientists and engineers with a clear and comprehensive understanding of composite materials. In describing both theoretical and practical aspects of their production, properties and usage, the book crosses the borders of many disciplines. Topics cover…
A strongly enhanced luminescence efficiency of zincborate glasses and glass fibers doped with trivalent europium or terbium is reported. The enhancement is attributed to a high content of direct gap ZnO nanocrystallites which operate as sensitizer for the rare-earth ions. The glasses have a low softening point and are…
We report the synthesis of nanocomposites of Bi in an aluminum based metallic glass matrix by rapid solidification. It is shown that constrained melting and solidification of nanometer sized embedded Bi particles lead to the formation of symmetry related multidomained particles. The Bi particles exhibit a significantl…
The magnetoresistance of single crystals of the quasi-two-dimensional (Q2D) organic conductor has been studied at temperatures between 700 mK and 300 K in magnetic fields of up to 15 T and hydrostatic pressures of up to 20 kbar. Measurements of the resistivity using a direct-current van der Pauw technique at ambient p…
Gold particles embedded in a polymer are studied using high resolution electron microscopy, nanodiffraction, and image processing. These particles have interesting properties such as nonlinear optical susceptibility. It is found that most of the nanoparticles are single crystals, and twins and planar defects are scarc…
We are able to grow high quality La0.67Sr0.33MnO3(LSMO) colossal magnetoresistive (CMR) thin films on Y-stabilized zirconia (YSZ) buffered (100) Si substrates using a Bi4Ti3O12 texturing and lattice matching layer. The CMR films have very high structural perfection and show excellent transport and ferromagnetic proper…