Materials Literature
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A theoretical investigation of the absorption coefficient of p-type doped porous silicon near the band edge is presented. We assume that the absorption coefficient is constructed by taking an average over a distribution (in terms of band gap) of absorption coefficients of individual crystallites. Exploiting physics fu…
A thick, homoepitaxial diamond film was deposited on the microcracked (100) tip of a brilliant cut type Ia natural diamond anvil by microwave plasma-assisted chemical vapor deposition (MPCVD). The rapid (up to 20 μm/h), highly anisotropic growth resulted in a modification of the original geometry of the central flat a…
We calculate ab initio the quasiparticle energies of MnO with a self-energy model derived from the $\mathrm{GW}$ approximation. We obtain good values of the energy gap (4.2 eV), magnetic moment (4.5 ${\ensuremath{\mu}}_{B}$), and on-site interaction $U$ ( $\ensuremath{\sim}8\mathrm{eV}$) and reproduce both energy and…
We derive the first nontrivial rigorous bounds on the mean distance between nearest neighbors $\ensuremath{\lambda}$ in ergodic, isotropic packings of hard $D$-dimensional spheres that depend on the packing fraction and nearest-neighbor distribution function. Several interesting implications of these bounds for equili…
High-pressure neutron diffraction studies of boron carbide, ${\mathrm{B}}_{4}$C, to 11 GPa show that the icosahedral structural units are 23(4)% more compressible than the structure between them. This inverted-molecular compression is in accordance with qualitative predictions based on models of the bonding, but had n…
Lead zirconate titanate (PZT) thin film was formed on Pt/Ta/Si3N4/Si(100) substrate at 400 °C by sputtering and then annealed at 650 °C in air. The PZT film was 1 μm thick and had dielectric permittivity of 980, loss tangent of 0.05, remanent polarization of 31 μC/cm2, and coercive field of 110 kV/cm. Piezoelectric pr…
Merely one step is required to synthesize the polymers 1. Depending on the substitution pattern (R1 H, SiMe3; R2 n-C6H13, n-C12H25), these polymers form lyotropic and/or thermotropic liquid crystalline phases.
General features of the electronic states of helically coiled cages of graphite layer are studied by simple tight-binding models. The topological structure of the cages, which is determined by the distributions of the 5-membered and 7-membered rings, governs the electronic behavior around the Fermi level. Unlike the c…
The self-assembly of monodisperse gold and silver colloid particles into monolayers on polymer-coated substrates yields macroscopic surfaces that are highly active for surface-enhanced Raman scattering (SERS). Particles are bound to the substrate through multiple bonds between the colloidal metal and functional groups…
The mismatch stress field in a graded epilayer and its substrate is analyzed by analogy to thermal stresses. In particular, a straight dislocation line and a half-rectangular dislocation loop in the graded epilayer are investigated. For the straight dislocation line, there are two positions in the epilayer at which th…
Thin films of molybdenum trioxide are prepared by the electron beam evaporation technique onto glass substrates maintained at temperatures in the range 303 to 523 K. The effect of substrate temperature and oxygen partial pressure on the structure and optical properties of MoO3 films is investigated. The as-deposited f…
We topologize a polycrystal composed of single crystals defined in a finite-dimensional affine space, to be a complete metric space. In the topological space “polycrystal”, we can find a compact domain with a self-similarity which is one of the geometrical properties characteristic of the complete metric space.
Equilibrium geometries of 60° dissociated misfit dislocations are considered theoretically using elasticity theory. The prediction of equilibrium dissociation width and the position of each partial with respect to the interface is given. The experimental results are in excellent agreement with the theory.
Diode properties of structures containing a porous silicon layer have been investigated. The structures have been fabricated by depositing metal or indium-tin-oxide layers either directly on the ‘‘as-anodized’’ silicon wafer or on the wafers with upper, nanocrystalline part of the porous layer removed. Different behav…
The results of a spin-polarized photoemission study of the Fe 3s level clearly reveal the multiplet structure characterizing the final states of the excitation process. The energy separation between the high-spin and low-spin ionic states of 3.5 eV is smaller than has previously been measured, to our knowledge. The tw…
In this paper we have investigated the composition-driven metal-insulator (MI) transitions in two AB${\mathrm{O}}_{3}$ classes of perovskite oxides (${\mathrm{LaNi}}_{\mathit{x}}$${\mathrm{Co}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{O}}_{3}$ and ${\mathrm{Na}}_{\mathit{x}}$${\mathrm{Ta}}_{\mathit{y}}$${\mathrm…
Several monolayers thick hydrogenated carbon films, C:H, were prepared by ion beam deposition from hydrocarbon process gases onto Pt and monolayer C covered Pt single crystal surfaces and investigated with Auger electron and thermal desorption spectroscopies in an UHV environment. Efficient deposition was achieved at…
The structural and electronic properties of yttrium trihydride with metal atoms in the hexagonal-close-packed (hcp) structure are studied by the pseudopotential method within the local-density-functional approximation (LDA). It is found that the hydrogen positions within the metal lattice have a major role in determin…
A model of the low-frequency Raman scattering intensity in glasses is proposed, which describes the spectrum in the region of the boson peak, typical of glasses. The model considers the boson peak as a result of first-order light scattering by harmonic quasilocalized vibrations. The amplitude, frequency, and polarizat…
Local-density calculations on the ${\mathrm{CrO}}_{2}$ (001) surface are reported. The half-metallic character of the bulk is found to be maintained at the surface. Surface states of oxygen p character at the top of the valence band for the semiconducting spin direction are discussed.