Materials Literature
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A new electron trap, labeled ED1, with an activation energy of 0.68 eV has been found to appear in the deep-level transient spectroscopy spectrum of n-type GaAs crystals as a result of their plastic deformation at 400 °C. The trap has been systematically investigated taking into account broadening of its energy level.…
An experimental study of the temperature- (T-) dependent dc and audio-frequency conductivity (\ensuremath{\sigma}) as a function of protonation level (0.0\ensuremath{\le}x\ensuremath{\equiv}[${\mathrm{H}}^{+}$]/[N]\ensuremath{\le}0.08) of emeraldine polymer is presented. The dc conductivity varies from ${10}^{\mathrm{…
Lead zirconate-titanate (PZT) thin films with tetragonal and rhombohedral structures have been successfully grown with good epitaxy on MgO single crystals and on [100]-oriented platinum thin films by rf-magnetron sputtering. The PZT films were obtained by using sputtering targets with compositions of Pb(ZrxTi1−x)O3, w…
The conductivity and dielectric constant of the emeraldine polymer are studied at a frequency of 6.5\ifmmode\times\else\texttimes\fi{}${10}^{9}$ Hz as a function of temperature T and protonation levels spanning from insulating emeraldine base [${\ensuremath{\sigma}}_{\mathrm{dc}}$(295 K)\ensuremath{\approxeq}${10}^{\m…
Theoretical calculations are presented for the figure of merit Z in thermoelectrics. The maximum values of Z are obtained in semiconductors which are doped so that the chemical potential is near the band edge. The highest Z is related to the B parameter of Chasmar and Stratton [J. Electron. Control 7, 52 (1959)].
We have developed an addition to the Steinberg–Guinan high strain-rate constitutive model that extends its validity to strain rates as low as 10−4 s−1. With this new model, we have successfully reproduced a number of rate-dependent, shock-induced phenomena in tantalum, such as precursor on reshock, precursor decay, an…
A simple extension of the Monkhorst-Pack Fourier-quadrature (or special-points) method for Brillouin-zone integration makes it possible to determine equivalent (identical by symmetry) points for two different unit cells simply by identifying lattice points common to both cells. This is useful for superlattice or super…
The nonlinear refractive indices (${n}_{2}$) of a large number of optical crystals have been measured at a wavelength near one micrometer with use of nearly degenerate three-wave mixing. The measurements are compared with the predictions of an empirical formula derived by Boling, Glass, and Owyoung. This formula, whic…
Abstract The binuclear Mn(III) complexes (I) and (VI) from Mn(III) acetate, sodium acetate, and the corresponding cyclic triamine undergo disproportionation reactions in aqueous solution under anaerobic conditions producing a variety of novel binuclear Mn(III),Mn(IV) and Mn(IV),Mn(IV) dimers such as (II), (IV), (VII),…
Several ferroelectric properties of triglycine sulphate single crystals both pure and with different doping substitutions in the structure have been studied in the vicinity of the critical point T c . The parameters engaged in the statistical dipolar theory of ferroelectrics are derived, from dielectric constant and h…
Recent Monte Carlo studies have demonstrated the existence of positionally ordered phases in systems of monodisperse, parallel hard spherocylinders. We present an excluded-volume theory of this system which utilizes a scaled-particle treatment of dimensions possessing full translational freedom combined with a simple…
It has been possible to identify two critical compositions in the IV-VI chalcogenide glassy system ${\mathrm{Ge}}_{x}{\mathrm{Se}}_{100\ensuremath{-}x}$ by the anomalous variations of the high-pressure electrical resistivity behavior. The first critical composition, the chemical threshold, refers to the stoichiometric…
This book will be useful to those involved in optical transmission and scanning electron microscopy (SEM) studies of polymers. The chapters include methods for morphological investigations and determination of fine structure (crystallinity, orientation) in various types of polymers and polymer blends. The effects of p…
ABSTRACT In order to protect production tubing from corrosion during acidic stimulation treatments at temperatures above 250°F (121°C), inhibitors containing heavy metals (copper, arsenic or antimony) have been employed. These metallic inhibitors are the subject of increasing regulatory control in the US and abroad. A…
Abstract Five structurally different scale inhibitors were studied using a kinetic adsorption-desorption technique. Adsorption was fast. All inhibitors adsorbed to a similar degree. Desorption was slow. There were large differences in the degree to which different inhibitors desorbed. The kinetic desorption characteri…
Abstract The occurrence of calcium sulfate scale in wells has recently become a sporadic major problem in producing wells in some CO2 floods.1 The problem has also been observed in wells where a potential scaling factor exists and the produced water has more than a fraction of a percent of carbon dioxide gas. Where ca…
An approach to the theory of unstable bound states of electrons in the nuclear field is suggested. This approach permits the determination of unstable bound states when a quasistationary approximation is unjustified and, therefore, methods normally used for this purpose in the atomic theory cannot be applied. The equa…
Mercuric reductase, with FAD and a reducible disulfide at the active site, catalyzes the two-electron reduction of Hg(II) by NADPH. Addition of reducing equivalents rapidly produces a spectrally distinct EH2 form of the enzyme containing oxidized FAD and reduced active site thiols. Formation of EH2 has previously been…
The mean asphericities (A d ) of open and closed Gaussian polymer chains are computed exactly and analytically (up to simple quadratures) for arbitrary space dimensions d. Excellent agreement is found with existing simulation data for d=2, 3, and 4. The authors' technique can also be used to compute other averages of…
Many glasses and liquids exhibit a first sharp diffraction peak that is evidence for intermediate-range order caused by regularities in the packing of structural units. These tend to cluster around particular values of the wavevector when scaled by the nearest-neighbour distance or the mean inter-atomic spacing. The f…