Materials Literature
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Abstract The aim of the work presented here is to develop a computer simulation technique which will predict the surface structure, the morphology and the rate of growth of carbonates. The technique is based on energy minimization in which all atom positions are varied until the lowest energy configuration is achieved…
Abstract The cyclic voltammograms of polyaniline prepared electrochemically were examined in the range −0.2 to 1.0 V vs. SCE in the presence and absence of aniline in the acqueous solution of HBF 4 . Cyclic voltammetry studies show that the polymeric film suffers degradation when the potential exceeds +0.85 V, and bel…
We present a chemical perturbation method for surface-structure determination by low-energy electron diffraction (LEED). It is based on tensor LEED theory and is able to substitute selected surface atoms by other chemical species making full dynamical calculations for the structure unnecessary. The potential of the ap…
The electromigration characteristics and kinetics of damage formation for Al(Cu,Si) line segments on a continuous W line and Al(Cu)/W two-level interconnect structures have been investigated. The mass transport as a function of temperature was measured using a drift-velocity technique. The flux divergence at the line/…
Polycrystalline samples of Ba2Cu2xZn2−2xFe28O46 (0≤X≤1) X-type hexaferrites were prepared by the classical ceramic method. Low-temperature magnetic properties and Curie temperature were investigated. The substitution of Zn2+ ion with Cu2+ ion leads to a decrease of the magnetic moment and an increase of Curie temperat…
We study theoretically the collective modes in charge-density waves in the presence of long-range Coulomb interaction. We find that earlier works by Takada and his collaborators are inadequate since they introduced inconsistent approximations in evaluating a variety of correlation functions. The amplitude mode is unaf…
Magnetic and structural studies of giant metal (M)-insulator (I)-metal reentrant transitions in the partially deuterated molecular conductors (DMe-DCNQI- d n ) 2 Cu ( n =2, 3) are presented. In the insulating phase, Curie-Weiss-like susceptibilities with reduced Curie constants and diffusive satellite reflections show…
The optical-absorption edge of zinc-blende-structure boron nitride has been measured at high pressure to 1.8 GPa using a sapphire-anvil cell. The effect of pressure on the minimum band gap is found to be 6.0 meV/GPa, which is greater than twice the value found in recent ab initio calculations.
Abstract Ethylene‐propylene‐diene rubber (EPDM) and isobutylene‐isoprene rubber (IIR) were compounded, precured to a low degree, and then were blended with natural rubber (NR). The compounding ingredients for NR were then added and the final curing was done. NR/EPDM and NR/IIR blends, prepared using this method, were…
Measurements of electrical resistivity versus temperature are reported for single-crystal specimens of the ${\mathrm{Fe}}_{3\mathrm{\ensuremath{-}}\mathit{y}}$${\mathrm{Ti}}_{\mathit{y}}$${\mathrm{O}}_{4}$ system in the composition range 0y0.9 and are compared to similar studies on ${\mathrm{Fe}}_{3\mathrm{\ensuremath…
The dielectric functions of several boron carbides with composition spanning the single-phase region (9--19 at. % C) have been measured over a broad range of frequencies (${10}^{2}$--${10}^{15}$ Hz), making it possible to evaluate the various polarization contributions to the dielectric response. The high-frequency (e…
Low-resistance ohmic contacts have been fabricated on a naturally occurring B-doped diamond crystal and on polycrystalline diamond films by B ion implantation and subsequent Ti/Au bilayer metallization. A high B concentration was obtained at the surface by ion implantation, a post-implant anneal, and a subsequent chem…
The pressure dependence of vibrational Raman scattering in polycrystalline ${\mathrm{Ge}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Si}}_{\mathit{x}}$ alloys is studied up to \ensuremath{\sim}100 kbar across the compositional range, and the mode Gr\"uneisen parameters \ensuremath{\gamma} for the Si-Si, Ge-Ge, and…
Electrical characteristics associated with radiation detection were measured on single-crystal natural type-IIa diamond using two techniques: charged particle-induced conductivity and time-resolved transient photoinduced conductivity. The two techniques complement each other: The charged particle-induced conductivity…
We present geometric and energetic properties of sodium clusters with 8, 14, 20, 30, and 40 atoms using an effective many-body interaction among sodium atoms in the framework of an improved isothermal molecular-dynamics approach. These clusters undergo two phase transitions and the two transition temperatures increase…
Angle-resolved ultraviolet photoelectron spectra using synchrotron radiation were measured for oriented thin films of bis(1,2,5-thiadiazolo)-p-quinobis(1,3-dithiole) on a cleaved highly oriented pyrolytic graphite (HOPG) surface. The observed takeoff angle dependence of the photoelectron intensity was analyzed by usin…
We investigate size-dependent nonlinear polarization due to Wannier excitons confined in CuCl quantum dots (QD's) with a radius R of 15--80 \AA{} embedded in glass. The third-order optical susceptibility ${\mathrm{\ensuremath{\chi}}}^{(3)}$ measured at 80 K increases as a function of radius and subsequently decreases…
The surface phonons and CH vibrational structure of diamond (100) and (111) surfaces have been examined using high-resolution electron-energy-loss spectroscopy. Experimental phonon features of (2\ifmmode\times\else\texttimes\fi{}1)-reconstructed diamond surfaces [H-free (100) and partially H-terminated (111)] agree we…
Abstract Polyimide fibers have been produced from both polyamic acid and polyimide resins, derived from 2, 2‐bis (3,4‐dicarboxyphenyl) hexafluoropropane dianhydride and 2, 2‐bis (4‐4‐aminophenoxy) phenyl) hexafluoropropane, by extrusion into various aqueous organic media. Polyimide fibers obtained from polyamic acid f…
We present a formalism to compute the optical-activity tensor in the long-wavelength limit neglecting local-field corrections with a nearly first-principles approach. The calculation of optical activity requires perturbation theory in the vector potential in order to describe the rotation of the plane of polarization…