Materials Literature
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The desorption of As from GaAs (001), (111)B, and AlAs(001) is studied in detail by measuring the electron-beam current reflected from these surfaces. When the As supply to the surface was terminated, the electron specular reflectivity decreases exponentially with time due to the As desorption. The decay rate was much…
Abstract Direct current (dc) and alternating current (ac) electrical properties of semicrystalline poly(butylene terephthalate) (PBT) are investigated as a function of temperature and frequency. Dc electrical conductivity measurements have been performed over the temperature range −75°C to 130°C and point out an essen…
Thulium (Tm) emissions were investigated in 390 keV, Tm-implanted AlGaAs, GaAs, InP, and Si using photoluminescence spectroscopy. The emissions in the different semiconductors were observed in the 1.20 to 1.35-μm region and are attributed to transitions between the crystal-field-split spin–orbit levels 3H5– 3H6 of Tm3…
Pressure dependence of the electrical conductivity of a range of polypyrrole samples doped to various levels is interpreted in terms of variable-range hopping theory. All samples are well described by a model that treats the density of localized states around the Fermi level as the pressure-dependent commodity. The pr…
Using an expansion of \ensuremath{\sim}12 700 plane waves, we calculate the lattice constants and heat of formation of tetragonal ${\mathrm{B}}_{50}$, ${\mathrm{B}}_{48}$${\mathrm{C}}_{2}$ (${\mathrm{B}}_{50}$${\mathrm{C}}_{2}$${)}_{\mathrm{\ensuremath{\alpha}}}$, (${\mathrm{B}}_{50}$${\mathrm{C}}_{2}$${)}_{\mathrm{\e…
We investigate the size evolution of bonding in magnesium clusters ${\mathrm{Mg}}_{\mathit{n}}$, with n\ensuremath{\le}20. Computations are performed in the density-functional scheme with two prescriptions for the exchange-correlation energy: the local-density approximation (LDA), and an improved scheme including grad…
The most pronounced effects of elastic scattering in solids are observed in electron backscattering experiments, which, as a result, offer the possibility to test the completeness of the theoretical models of electron transport. For this purpose, elastic backscattering from the Au/Ni(111) system was studied in the pre…
Molecular structures, harmonic vibrational frequencies, and infrared intensities for diborane B2H6, dialane Al2H6, and digallane Ga2H6 have been determined using high level ab initio quantum mechanical methods. The highest level of theory employed in this study is the single and double excitation coupled cluster (CCSD…
The electromigration diffusion boundary value problem with the perfectly blocking diffusion barrier is numerically investigated. Three possible boundary conditions are identified as physically meaningful and the solutions compared at the blocking barrier. It is seen that the solution of M. Shatzkes and J. R. Lloyd [J.…
The electrification of polymethyl methacrylate films is studied by scanning force microscopy. Charged areas generated by contact electrification are always found to be larger than those generated by corona discharge, and are surprisingly much larger than the area of contact. After each single contact made with the met…
We present first-principles calculations for the optical properties of titanium dioxide in the rutile structure. The electronic band structure has been calculated self-consistently within the local-density approximation using ab initio pseudopotentials and a plane-wave basis. Optical properties are determined from the…
Abstract Thermal behavior of brominated atactic polypropylene (BAPP), obtained by thermal bromination of atactic polypropylene (APP), was evaluated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). It was found that the initial decomposition temperature (IDT) and char yield increase with the…
Abstract This paper presents a novel process developed to manufacture poly(methyl methacrylate) (PMMA) pultruded composite. The mechanical, thermal, and dynamic mechanical properties, environmental effect, postformability of various fiber (glass, carbon, and Kevlar 49 aramid fiber) reinforced pultruded PMMA composites…
The ${\mathrm{VC}}_{0.80}$(111) surface forms a metastable 1\ifmmode\times\else\texttimes\fi{}1 structure upon argon-ion bombardment and annealing at a temperature not exceeding 1000 K. We study this structure by low-energy electron diffraction and are able to determine the relaxation and composition of a four-layer s…
Self-energy effects (frequency shifts and line broadenings) due to isotopic disorder on the off-zone-center (q\ensuremath{\ne}0) phonon spectra in natural Ge have been investigated by comparing infrared transmission spectra of an isotopically enriched germanium crystal (86% $^{76}\mathrm{Ge}$) and a natural Ge crystal…
The reference interaction site model (RISM) integral-equation approach to polymeric liquids is generalized to allow a self-consistent determination of single-chain and intermolecular pair correlations. Nonlinear medium-induced effects on intrachain statistics are described at the level of self-consistent pair interact…
The study of the electronic properties of small particles is of major interest because of their intriguing physicochemical properties. The very small electron probes available in scanning transmission electron microscopes offer unique capabilities for investigating small particles with subnanometer spatial resolution.…
The static longitudinal dielectric function εL(k) is calculated for several polar interaction site model (ISM) fluids for comparison with related models having arbitrary short-range interactions and a set of one or more lower-order multipole moments at the centers (ΩM models). The requisite averages over the ISM fluid…
We have investigated the effect of pressure on the lowest direct band-edge exciton of the layered semiconductor InSe by optical-absorption measurements at 10 K and for pressures up to 4 GPa. The Elliott-Toyozawa formalism is used to analyze the line shape of the exciton absorption spectra. In this way we determine the…
Abstract Cellulosic materials, namely bleached bamboo pulp, jute fibers, and sawdust dyed with a reactive dye of monochlorotriazine type were used in the column studies for removal of different metal ions. The use of an adsorption column makes the process continuous, so that it is economically viable on an industrial…