Materials Literature
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Complex perovskite A(B′B″)O3 ceramics with various degrees of B-site order have been structurally and spectroscopically characterized by means of x-ray diffraction, transmission electron microscopy, and infrared reflectivity. In Ba(Fe1/2Nb1/2)O3 and Pb(Fe1/2Nb1/2)O3, no order could be detected whereas Pb(In1/2Nb1/2)O3…
Hydrogen-, oxygen-, and nitrogen-related defects in chemical-vapor-deposited (CVD) diamond have been observed by infrared spectroscopy and found to affect optical absorptions in spectral regions of commercial interest. The origin of absorptions in the infrared spectrum at 2820 and 2833 cm−1, which have been observed p…
This paper addresses some important questions concerning hopping conduction in doped conducting polymers, i.e., dimensionality, homogeneity, adiabaticity, Coulomb interactions, and multiphonon character. It will be shown that electron transport in these materials is due to correlated hopping between polaronic clusters…
Ferroelectric capacitors having Pt bottom and top electrodes and a ferroelectric film of composition PbZr0.51Ti0.49O3 (PZT) were fabricated and investigated. The PZT films of thicknesses varying from 0.12 to 0.69 μm were prepared by organometallic chemical-vapor deposition. Annealed capacitors were investigated by cap…
We propose a family of nanotubules originating from a hexagonal ${\mathrm{BC}}_{2}$N sheet. Because of the anisotropic structure of the ${\mathrm{BC}}_{2}$N sheet, there are a variety of ways to obtain chiral structures by rolling the ${\mathrm{BC}}_{2}$N sheets into tubules. We performed first-principles and tight-bi…
A negative electron affinity (NEA) was found both experimentally by photoemission spectroscopy and theoretically by ab initio calculations for the 2\ifmmode\times\else\texttimes\fi{}1 reconstructed diamond (100) surface. This surface is the dominant growth surface for thin diamond films and can be obtained by chemical…
The ground-state electronic structure of NiO and MnO has been calculated within the Hartree-Fock approximation using local Gaussian basis sets. For both, a qualitatively correct ground-state electronic structure is obtained in which the wide-band-gap insulating character of these materials is seen to be a result of la…
Powdered samples of the type Ce1−xRExO2−y, where RE=La, Pr, Nd, Eu, Gd, and Tb, are synthesized over the range 0≤x≤0.5 starting from nitrate solutions of the rare earths. X-ray diffraction and Raman scattering are used to analyze the samples. These compounds, at least in the low doping regime and for strictly trivalen…
In this paper, the relationships between phenomenological and thermodynamic models used for characterization of insulating materials aged under multiple thermal-electrical stresses are derived. Phenomenological models fitting life lines for insulating materials that show or do not show a tendency to threshold are cons…
A practical review of the use of laser ablation for the deposition of thin films of oxide superconductors and metals is presented. Details of the design and operation of a laser ablation deposition system are discussed, together with the influence of operating parameters such as laser wavelength and power density on t…
In this paper we present results on the dependence of the longitudinal sound velocity of amorphous magnetostrictive ribbons and wires, tested either in the as-cast stage or after stress relief on the magnetic field along the anisotropy axis. Results show a variation of the sound velocity that is in good agreement with…
The effects of ultraviolet light on alpha -Al 2 O 3 :C crystals were studied. Thermoluminescence, X-ray-induced luminescence and photostimulated thermoluminescence were investigated. Emission as well as stimulation spectra were measured. The main thermoluminescence and photostimulated thermoluminescence peaks appeared…
A model for the heat transfer between a heating element and a thermoluminescent sample in the case of contact heating is used to estimate the temperature lag of the sample with respect to the heating element during linear heating. According to the model the temperature lag is linearly dependent on the heating rate bet…
The microphase separation in a symmetric diblock copolymer consisting of polystyrene and polyparamethylstyrene has been studied by small-angle neutron scattering. The observed peak changes with temperature in intensity, shape and position. The peak position shifts at the microphase separation transition temperature T…
An investigation on the local structure of liquid and supercooled pure gallium at several temperatures is presented. Accurate EXAFS (Extended X-ray Absorption Fine Structure) spectra have been analysed by means of ab initio calculations of the multiple-scattering signals associated with two-atom and three-atom configu…
We have designed and built a new apparatus for measuring the thermal conductivity of molten silicates, an adaptation of the transient hot‐wire technique to high temperature. The method is the most suitable for high temperatures, as it suppresses convection and minimizes radiative heat transfer. Because of the simple g…
The long-time self-diffusivity in concentrated colloidal dispersions is determined from a consideration of the temporal decay of density fluctuations. For hydrodynamically interacting Brownian particles the long-time self-diffusivity, D s ∞, is shown to be expressible as the product of the hydrodynamically determined…
The effects of plates and slabs on phase change dynamics have been investigated with convection models. Two complementary methods to simulate plates are used: material property and imposed surface velocity methods with temperature‐dependent viscosity. For a wide range of model parameters, plates and slabs exert a sign…
The method of X-ray crystallographic cryoenzymology has been used to determine the crystal structure of a kinetically significant species on the reaction pathway of a crystalline enzyme. The structure of a specific acyl-enzyme intermediate in the elastase-catalyzed hydrolysis of the N-carbobenzoxy-L-alanine p-nitrophe…
Abstract New polythioesters were obtained by interfacial polycondensation of bis(4‐mercaptomethylphenyl) sulfide with some aliphatic and isomeric phthaloyl dichlorides. To determine optimal conditions for polycondensation, the polythioester from bis(4‐mercaptomethylphenyl) sulfide and sebacoyl dichloride was chosen as…