Materials Literature
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We present a model of tetrahedral amorphous carbon (with density 3.0 g ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$) obtained from self-consistent plane-wave (Car-Parrinello) methods. This model is closely related to one we presented earlier [Phys. Rev. B 49, 16 415 (1994)], except for an even greater tendency toward ${…
Glass beads were encapsulated by grafted polymers: polybutylacrylate and polystyrene. Grafting was performed by the polymerization initiated from the particle surface with preliminary adsorbed polyperoxide initiator. Grafting procedure and properties of grafted film were studied using model substrates: powders, plates…
We analyzed the photoluminescence (PL) mechanisms of porous silicon, and in particular, the origin of the PL high quantum efficiency (QE) at room temperature. For this we used postformation treatments, anodic oxidation, and hydrofluoric acid (HF) etching (known for their strong QE enhancement effect) correlated with a…
Electrical switching properties of Ge-As-Te glasses have been investigated over a wide range of mean coordination numbers (〈r〉) in a single composition tie line. The results obtained clearly indicate the modulation of the composition dependence of switching fields by network topology. Distinct change is observed in th…
Photothermal deflection spectroscopy (PDS) is used to study subgap optical absorption in chemical vapor deposited (CVD) diamond films. The high PDS sensitivity over a broad investigated spectral range enabled the investigation of the main defect structure in CVD diamond upon changing the deposition conditions. All fil…
Twenty elements were codeposited with carbon in an arc discharge between graphite electrodes. The majority of them were evaporated from composite anodes that contained the elements or their oxides stuffed into central bores in the graphite rods. The deposits, found in the soot at the reactor walls or as slag at the ca…
It is shown that charge transport in SiC ceramics includes atomic mechanisms as well as phenomena which depend on the microstructure of the material. Both aspects are revealed by the analysis of temperature-dependent dc and ac measurements. The complex dielectric function (DF) of boron-doped SiC ceramics with various…
We carry out a calculation of the phonon-drag contribution ${\mathit{S}}_{\mathit{g}}$ to the thermoelectric power of bulk semiconductors and quantum well structures using the balance equation transport theory extended to weakly nonuniform systems. Introducing temperature-, wave-vector-, and mode-dependent phonon rela…
Four aluminum-jacketed, fluorine-doped silica clad optical fibers with silica core materials fabricated by differing technologies were subjected to sequential 60Co-γ ray and fission-reactor irradiations (at ∼20 and 40 °C, respectively), an intervening isothermal anneal (∼20 °C), and a final isochronal anneal (to 600 °…
The isotropic–nematic (I-N) phase transition in hard ellipsoid fluids has been studied by computer simulation, using the Gibbs–Duhem integration technique introduced by Kofke; and theoretically, using Onsager theory and the Parsons–Lee improvement. In the simulations, the I-N coexistence line is mapped out in the P–x…
Polycrystalline Bi4Ti3O12 thin films having layered perovskite structure were fabricated by metalorganic solution deposition technique on both Pt-coated Si and bare Si substrates at a temperature as low as 500 °C. The effects of post-deposition rapid thermal annealing on the structural and electrical properties were a…
Thin films of Si nanoclusters passivated with oxygen or hydrogen, with an average size of a few nanometers, have been synthesized by thermal vaporization of Si in an Ar buffer gas, followed by subsequent exposure to oxygen or atomic hydrogen. High-resolution transmission electron microscopy and x-ray diffraction revea…
Irradiation of multiwalled carbon nanotubes with the 800-keV electron beam of a transmission electron microscope induces anisotropic collapse of the nanotube. Tight-binding molecular-dynamics simulations of tube response following momentum transfer from large-angle electron-nuclear collisions reveal a strongly anisotr…
The charge-ordered insulating state of ${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$ below the Verwey transition temperature has been studied by the modified local density approximation with Coulomb interaction correction method. The charge ordering is found to be a stable solution with an energy gap value of 0.34 eV (the exp…
We use analytic techniques and the dynamical mean-field method to study the crossover from Fermi liquid to polaron behavior in models of electrons interacting with dispersionless classical phonons. \textcopyright{} 1996 The American Physical Society.
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…