Materials Literature
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A method for measuring and interpreting the Seebeck coefficient in high resistivity (≧ 105 Ωcm) materials is discussed; the technique is applied to pure V2O3 between 50 and 300 K. The results indicate that the low temperature phase of V2O3 is a band-type semiconductor.
The elastic moduli of a number of semiconducting phosphate glasses have been measured by ultrasonic techniques at 12 MHz. The dependence of elastic stiffness on glass composition is given for glasses of the MoO3–P2O5 and V2O5–P2O5 systems. The Debye temperatures of the phosphate glasses are in the range 300 to 450 K.
A model is developed for the green-yellow emitting centre in PbMoO4 and PbWO4 in terms of an excited state which can be visualized as Pb3+-XO3−4, i.e. an electron localized at XO and an electron-hole at one of the surrounding Pb2+ ions. The different levels of the triplet excited state arise from splitting due to the…
Ultraviolet spectroscopy confirms the findings of solubility studies that Sb(III) in 3–12 M hydrochloric acid solutions is present as an equilibrium mixture of SbCl 4 − and SbCl 6 3− ions. In the presence of H 2 SO 4 a further equilibrium with the SbCl 3 (HSO 4 ) − ion is found. The spectrum of the SbCl 6 3− ion in so…
The helicity amplitudes for electron-electron scattering to order ${e}^{4}$ are calculated by using the five invariant amplitudes presented in a previous paper. As applications, we rederive the unpolarized cross section given by Polovin and the spin-momentum correlation result obtained by Barut and Fronsdal.
Chloro−(tetraphenylporphinato)chromium(III) shows relatively normal visible (Q) bands in the region 610−500 nm and a relatively normal Soret (B) band at 447 nm; in addition, there are prominent bands in the near uv region 400−300 nm (2×104 < ε < 3×104 M−1⋅cm−1) and clear near ir bands in the region 820−6…
Exact calculations of heat flows and thermal conductivities in disordered harmonic chains of up to 50 atoms have been made within the framework of the self-consistent reservoir model. Thermal conductivities, obeying Fourier's law, are given as functions of the coupling to the internal heat baths for both fixed-end and…
A linear combination of localized orbitals-molecular orbital (LCLO-MO) cluster method is applied to calculate the electronic structure of ${{E}_{1}}^{\ensuremath{'}}$ centers in the $\ensuremath{\alpha}$-quartz structure of Si${\mathrm{O}}_{2}$. An ${\mathrm{O}}^{\ensuremath{-}}$ vacancy model, implying a net charge o…
Phase relationships in the copper/selenium system in the composition range 30–70 atomic % selenium have been studied at temperatures from 298 to 850 K and at pressures to 50 kbar. A revised atmospheric pressure phase diagram is given, as well as an outline of the phase diagram at 20 kbar.αCu 2 Se is monoclinic at 298…
Substitutional and displaced carbon impurities and an isolated nitrogen vacancy in hexagonal boron nitride are theoretically investigated by the "small periodic cluster" approach. The perfect-solid band structure is calculated from the solution of the eigenvalues of a finite and periodic cluster of atoms arranged acco…
Calculations of the vibrational density of states and the Raman and infrared spectra have been performed for random-network, microcrystalline, and polymorph structures of Si and Ge. The polymorphs considered include Si III, Ge III, and two clathrate structures. The calculations are based on simple semiempirical forms…
When hexagonal boron nitride is exposed to ionizing radiation two types of paramagnetic centers appear: three-boron centers and one-boron centers. Results of electron paramagnetic resonance, thermoluminescence, and thermally-stimulated-current measurements associated with these centers are described, and a model is pr…
Light and electron microscopic examinations have been made on a number of species previously attributed to the genus Amphipleura Kütz. As a result, two groups of species can be delimited, both of which warrant generic status. The genus Berkeleya Greville is therefore extended to include the marine tube-dwelling specie…
The discharge space between a positive cylindrical electrode (in the diameter range 0.3185-3.175 cm) and a coaxial outer electrode of diameter 58.1 cm has been irradiated by a radioactive beta -source to obtain a stable glow discharge in which streamers are absent. Onset electric gradient, voltage-current characterist…
Proteins taken directly from the Bombyx mori silk gland have been separated and identified as either fibroin or sericin on the basis of their location within the gland and their amino acid composition. Molecular weights of these polypeptides have been determined by sodium dodecyl sulfate polyacrylamide gel electrophor…
Abstract The diffusion of water vapour through samples of cured and uncured fleece and fibreglass wool was measured. The diffusion resistance of the fibreglass was close to the value expected for still air, i.e. 4.2 s cm-1 per centimetre for samples ranging in depth from 1 to 7 cm. The resistance for natural fleece wa…
Ultrafine particles of Ni${\mathrm{Fe}}_{2}$${\mathrm{O}}_{4}$ coated with organic molecules show a behavior consistent with extremely strong pinning of the ferrite surface spins. The low-temperature magnetization is only \ensuremath{\sim}75% saturated in fields of 200 kOe, and M\"ossbauer spectra show that the spins…
The inorganic crystalline polymer polysulfur nitride has been found to become superconducting with a transition temperature of (0.26\ifmmode\pm\else\textpm\fi{}0.03)\ifmmode^\circ\else\textdegree\fi{}K.
Resistivity measurements on crystals of ${({\mathrm{V}}_{0.99}{\mathrm{Cr}}_{0.01})}_{2}$${\mathrm{O}}_{3}$ grown by vapor transport confirm our earlier results. They do not support the reinterpretation of metal-insulator transition given by Honig, Chandrashekhar, and Sinha in a recent Letter.
An analytical model has been developed to simulate the thermal NOx emission processes in various gas turbine combustors for a variety of fuels. The NOx emissions predicted by the model are in excellent agreement with available laboratory and field data. Its capability to simulate the water injection process accurately…