Materials Literature
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A set of central interionic potentials for the rubidium halides is presented. These potentials, which are based on a shell-model description, are fitted to solid state data and are used in molecular dynamics simulations of the ionic melts. The partial radial distribution functions, the velocity autocorrelation functio…
The nature of the charge carriers in n-type BaTiO 3 is discussed in the light of recent investigations into their mobility (T<or=1500K) and defect chemistry. Evidence is found for small polaron formation. Mobility enhancement-probably due to correlated hopping-must be assumed in order to furnish a consistent explanati…
The ${[\mathrm{Li}]}^{0}$ center has been formed in lithium-doped single crystals of MgO by high temperature quenching. In contrast to the ${[\mathrm{Li}]}^{0}$ center formed by low-temperature $\ensuremath{\gamma}$ irradiation, the center formed by quenching is stable at room temperature. A heavy electron irradiation…
A pressure-induced tricritical point is indicated for ${\mathrm{KH}}_{2}$${\mathrm{PO}}_{4}$ near 2 kbar pressure. This estimate is based on analysis of our static dielectric data for pressures up to 3 kbar.
The existence of a hexagonal (wurtzite) form of silicon, similar to that form of diamond (carbon) observed in meteorites and in the laboratory, has been identified by x-ray diffraction in reaction-bonded silicon nitride containing unreacted silicon. The presence of this phase is due to stresses created in the silicon…
Polyphosphazenes are emerging as a new class of macromolecules that have an obvious future as technological elastomers, films, fibers, and textile treatment agents. However, they also possess almost unique attributes for use in biomedicine as reconstructive plastics or as drug-carrier molecules. Moreover, their possib…
With glass capillary pressure vessels it has been possible to study the effect of pressure on the temperature of maximum density (TMD) and on the "sharpness" of the density maximum in liquid H(2)O and D(2)O in the important but little-studied supercooled regime. A pressure of 1200 bars produces a 33 degrees C depressi…
High-purity Ni is used for quenching experiments in a He cryostat, the electrical resistivity being used as a defect indicator. The quenched-in resistivity recovers in two stages: a steep one, A, around 120°C with a decrease of 50% and a rather broad one, B, around 560°C with a decrease of 45%. The formation energy of…
Polarized measurements of the reflectance and temperature-modulated reflectance spectra of ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$ in the range of 0.5-5.8 eV are reported. The experimental results strongly support the level scheme of Goodenough and are in good agreement with the theoretical model of Ashkenazi and Chuchem…
A high temperature vaporization study of the scandium–sulfur system has shown that a defect scandium monosulfide phase with composition Sc/S=0.8065 vaporizes congruently over the temperature range 1875–2220 K. High temperature mass spectrometric results show that the congruently subliming phase has two principle vapor…
This paper presents a study of the broadening and splittings of bound-hole excitation lines in silicon when the excitation energy is comparable to that of optical phonons. The approach utilized is a generalization of a similar study for donors in which the degeneracies of the ground and excited states do not play an e…
Hydrogen arrangements in two polymorphic forms, β 1 and β 2 , of V 2 H have been studied by powder neutron diffraction up to 200°C. The hydrogen atoms in β 1 -V 2 H are fully ordered in the specific o z -sites of the body-centered pseudo-tetragonal vanadium lattice ( c 0 / a 0 ≃1.1), forming a monoclinic superstructur…
The fundamental absorption spectra of evaporated thin films of La- and Ce-halides have been measured over a photon energy range from 3 to 40 eV. The fine structures occurring below the threshold in Ce-halides are ascribed to the 4 f →5 d transition of cerium ion. The Cl - L 2,3 absorption spectra of LaCl 3 and CeCl 3…
This is the first of a two part study of a statistical mechanical system that exhibits an isostructural phase transition at high density and pressure. Here, in Paper I, we consider a one-dimensional fluid; in Paper II we go on to treat the same system in three dimensions, using the approximation methods developed and…
We describe the excess Raman intensity recently observed by Winterling in vitreous silica for frequency shifts $\ensuremath{\omega}<20$ ${\mathrm{cm}}^{\ensuremath{-}1}$ in terms of structural relaxation of defects, which can have two distinct states of polarizability differing by an amount $\ensuremath{\Delta}\ens…
The phonon dispersion relation of the one-dimensional conductor, deuterated tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ), has been studied by inelastic neutron scattering over a temperature range of 60-300 K. Acoustic phonons propagating along the chain direction (the monoclinic ${b}^{*}$ direction) are stud…
We have measured the second and third order hyperpolarizabilities β and γ using the technique of electric field induced second harmonic generation in a variety of weakly associating (e.g., nitrobenzene–benzene) and strongly associating (e.g., water–methanol) liquid mixtures. These experiments are shown to yield intere…
Electrical field dependence of the dielectric constant in KTaO 3 has been measured under the bias field up to 15 kV/cm and in the temperature range between 300 K and 4.2 K. Characteristics of the induced polarization as functions of electric field and of temperature were obtained. A hysteresis phenomenon in the biasin…
We have calculated the effect on the surface-plasmon-polariton dispersion of a space-charge layer at a semiconductor surface, representing it by a dielectric function $\ensuremath{\epsilon}(\ensuremath{\omega})$ that has an exponentially varying part with a $\frac{1}{e}$ decay depth of the order of the layer thickness…
A paramagnetic centre having spin S=2 and C 2 symmetry has been detected in natural amethyst crystals. The only ESR transition observed was the Delta M=+or-4 transition between the lowest two energy levels M=+or-2. Line position measurements at 35 GHz and 16 GHz gave the g-tensor principal value for the C 2 direction…