Materials Literature
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Detailed measurements of the temperature dependence of the EPR spectrum and Hall coefficient of niobium-doped rutile have been made. At 4.2 \ifmmode^\circ\else\textdegree\fi{}K and 34 GHz, the EPR spectrum consists of a set of well-resolved hyperfine lines which coalesce and then shift with increasing temperature. Com…
Torsional stress pulses of several microseconds duration were applied at 4.2 \ifmmode^\circ\else\textdegree\fi{}K to cylindrical single crystals of copper containing freshly introduced dislocations. Dislocation displacements were measured by means of a double-etch technique, and subsequently the dislocation damping co…
New measurements of electrical conductivity and Hall constants have been performed on single crystals of ${\mathrm{Na}}_{x}\mathrm{W}{\mathrm{O}}_{3}$ for $0.22<x<0.63$ and temperatures from 1.2 to 300 K. The conductivity varies with $x$ according to the relation, $\ensuremath{\sigma}\ensuremath{\propto}{(x\ensu…
The two theoretical approaches to extended x-ray-absorption fine structure, based on either "long-range order" or "short-range order" are critically examined within a muffin-tin-scatterer model. It is argued that the two apparently dissimilar theories will in practice yield essentially the same results. The argument i…
Vibrational excitation of ${\mathrm{O}}_{2}$ by electrons in the energy range 4-15 eV is studied with a crossed-beam double electrostatic analyzer. The differential vibrational cross sections for $v=1\ensuremath{-}4$ at 25\ifmmode^\circ\else\textdegree\fi{} show a bell-shaped energy dependence peaked near 9.5 eV. The…
The use of VO2 films for direct-bit optical storage with near-infrared lasers is demonstrated. The VO2 response is fast (&lt; 10 ns), and large read signals are obtained with unpolarized light. A writing threshold of 0.03 nJ/μm2 is observed.
Large reversible thermochromic changes in pure and transition-metal-doped SrTi${\mathrm{O}}_{3}$ were observed which depend markedly on impurity concentration, anealing temperature, and especially on the rapidity of the quench. The material also changes its electrical properties from insulator to semimetallic, and for…
An electronic structure, in terms of molecular orbitals, is suggested for the layered compound Ti${\mathrm{S}}_{2}$. This structure is based on the combined $\mathrm{Ti}{L}_{\mathrm{III}}$, $\mathrm{Ti}K$, $\mathrm{S}{L}_{\mathrm{II},\mathrm{III}}$, and $\mathrm{S}K$ x-ray-emission and -absorption band spectra. The x-…
Orthorhombic CuFe 2 S 3 is weakly ferromagnetic. The magnetic susceptibilities of single-crystal and polycrystalline specimens have been determined at temperatures between 78 and 500 °K. A model is presented to explain the weak ferromagnetism.
X-ray photoelectron spectra of Na and Li metals were obtained in ultrahigh vacuum. Rich plasmon structures were observed on all peaks. Both the photoemission and Auger peaks showed large extra-atomic relaxation energies. A simple "equivalent-cores" screening model predicts extra-atomic relaxation energies in good agre…
Model calculations are presented which indicate that the character of the nematic-isotropic phase transition can be continuously changed from first to second order and that a new biaxial liquid crystal phase can be obtained by mixing suitable platelike and rodlike molecules. Precursors of the predicted behavior should…
The Fourier amplitude method developed in Paper I as a diagnostic tool for determining the sensitivity of the results of complex calculations to the parameters which enter these calculations has been applied to two chemical reaction systems involving sets of coupled, nonlinear rate equations. These were: (a) a five re…
The nonrelativistic augmented-plane-wave (APW) method is applied to calculate the electronic band structures of several transition-metal-dichalcogenide ($T{X}_{2}$) layer compounds, including materials with the $C6(1T\ensuremath{-}\mathrm{Hf}{\mathrm{S}}_{2},1T\ensuremath{-}\mathrm{Ta}{\mathrm{S}}_{2})$, $C27(2H\ensur…
We report a new technique for studying the effect of uniaxial stress and hydrostatic pressure on the N\'eel temperature of antiferromagnets. Using magnetoelectric susceptibility measurements, we studied the shift in the N\'eel temperature ${T}_{\mathrm{N}}$ of ${\mathrm{Cr}}_{2}$${\mathrm{O}}_{3}$ caused by an externa…
Scanning electron microscopy (SEM), invented 20 years ago, primarily gives three-dimensional surface details on a screen or photograph at magnifications comparable to a transmission electron microscope (TEM). Scanning electron microscopy may in time replace TEM, since excellent transmission micrographs can now be made…
Abstract Many attempts have been made in the past to bring order to the near-bewildering array of eutectic morphologies. These have met with limited success due mainly to the fact that the morphology of a particular eutectic may be highly dependent on both chemical composition and the rate of freezing. This paper show…
The results presented in the preceding section indicate several interesting trends. In the case of polyethylenes, one notes that the proportionality between dielectric constant and density relationship is obeyed as long as the molecular weight distributions of the polymer system are of the same modality. The dielectri…
X-ray powder data are given for Y3In2Ga3O12 and Ya3Sc2Ga3O12. The refined cell parameters are 12.548 and 12.482 A, respectively.
The distortion of longitudinal pulses in slightly curved elastic rods is discussed in terms of an elementary theory in which the effects of rotary inertia and radial shear are neglected. Moreover, when the wavelength of the pulse is long enough, practically all the bending effects can be justifiably neglected. The exp…
Boron carbide possessing porosities of 91 and 77%T.D. were irradiated at about 300°C to 6.0x1018∼ 3.3×1019 n/cm2 in helium atmosphere. The thermal conductivity, the electric resistivity and the linear thermal expansion were determined. Upon irradiation to 3.3×1019 n/cm2, cracking occurred in all of the 91%T.D. specime…