Materials Literature
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A simple model is proposed to explain how a breakdown avalanche of secondary emission electrons can lead to surface flashover when an insulator in vacuum breaks down a few nanoseconds after high voltage is applied. The case of a plane insulator–vacuum interface perpendicular to parallel electrodes is considered. Posit…
A method of equivalent linearization for smooth hysteretic systems under random excitation is proposed. The hysteretic restoring force is modeled by a nonlinear differential equation and the equation of motion is linearized directly in closed form without recourse to Krylov-Bogoliubov technique. Compared with previous…
Abstract In the present paper we consider not only the simplest periodic nets (such as arise from the equivalent circle packings of Niggli, Fejes Toth and others) but also less regular ones, ignored by mathematicians but nevertheless of widespread occurrence and usefulness in crystal chemistry. After a general introdu…
Preferential loss of uranium-234 relative to uranium-238 from rocks into solutions has long been attributed to recoiling alpha-emitting nuclei. Direct evidence has been obtained for two mechanisms, first, recoil ejection from grains, and now release by natural etching of alpha-recoil tracks. The observations have impl…
Abstract Some properties of poly(vinyl chloride) (PVC) and mixtures of PVC and polyurethanes (PUs) are discussed. Six different PUs of varying molar ratios of NCO/OH, and differing in the kind of glycol used as a chain extender were used as modifiers. It has been found that PVC modified with PUs has a lower tensile st…
The low-temperature thermal conductivity of three different types of natural diamond has been measured between 0.5 and 20K. It has been attempted to relate the infrared absorption features of the diamonds with their thermal conductivity. A diamond with only B features (i.e. no B' peak) in the infrared was found to con…
L'ordre cristallographique est complet dans CoMnP, c'est-à-dire le cobalt se situe en site tétraédrique et le manganèse en site pyramidal. La structure magnétique est essentiellement ferromagnétique de par l'arrangement des moments de manganèse (2,55 μB). L'introduction de manganèse dans les sites pyramidal puis tétra…
Tapered copper single crystals oriented for single slip are deformed plastically at room temperature and at 77 K. TEM investigations at resolved shear stress levels of 20, 30, and 40 MPa in the same crystal are used to follow the development of the dislocation structure with increasing deformation. Both, an open cell…
We report results of electrical-conductivity, thermoelectric-power, and optical experiments on single crystals of ${\mathrm{Ni}}_{1\ensuremath{-}x}{\mathrm{Co}}_{x}{\mathrm{S}}_{2}$ ($0\ensuremath{\le}x\ensuremath{\le}0.12$). The results cannot be explained by means of a conventional one-electron model. However, if it…
A chemical vapor deposition system for the growth of epitaxial (112̄0) ZnO films on (011̄2) sapphire, employing the reaction of zinc vapor and carbon dioxide, was investigated. Growth rates as high as 30 μm/h at a substrate temperature of 700-750 °C were achieved. Films grown on substrates with thin presputtered layer…
Infrared absorption of O${\mathrm{H}}^{\ensuremath{-}}$, O${\mathrm{D}}^{\ensuremath{-}}$, and O${\mathrm{T}}^{\ensuremath{-}}$ in $\ensuremath{\alpha}$-${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ at 77 K occurs at energies of 3282, 2439, and 2069 ${\mathrm{cm}}^{\ensuremath{-}1}$, respectively. A small band at 3266 ${\math…
We report an investigation of the uniaxial-stress dependence of the first-order Raman spectrum of rutile (Ti${\mathrm{O}}_{2}$). We find a normal-mode behavior, characterized by an increase in the phonon frequency versus uniaxial compression, for the two Raman modes ${\ensuremath{\Gamma}}_{1}$ (${A}_{1g}$) and ${\ensu…
The energies of the core levels and of the Auger peaks have been measured for the Pt-SrTi${\mathrm{O}}_{3}$(100) interface with different coverages of platinum. By comparing the core level and Auger chemical shifts for Pt, the changes in the total relaxation energy was obtained with different coverages of platinum. Th…
Hard diamondlike carbon layers have been deposited on silicon by rf plasma deposition using acetylene as working gas. For the first time the dependence of the sliding friction coefficient μ on the water vapor content of a nitrogen atmosphere was measured. An increase of μ with increasing humidity has been found, with…
Small unilamellar neutral, negatively and positively charged liposomes composed of egg phosphatidylcholine, various amounts of cholesterol and, when appropriate, phosphatidic acid or stearylamine and containing 6-carboxyfluorescein were injected into mice, incubated with mouse whole blood, plasma or serum or stored at…
A variety of 'Universal Yield Curves' for the secondary emission process have been proposed. A series of precise measurements of the secondary emission properties of a range of related amorphous semiconducting materials, made under UHV on freshly vacuum-cleaved surfaces, and covering a wide range of primary energies,…
The dependence of the resistivity of various spinel ferrites upon firing temperature has been studied. It has been determined that the resistivity of spinel ferrites has a maximum, which occurs in samples fired at 1300 degrees C. From impurity doping, the conduction in spinel ferrites can be classified into two types,…
Capillary shear flow of a magnetically aligned liquid crystal was studied in the three Miesowicz orientations in the nematic, the smectic-$A$ and, for the first time, in the reentrant nematic phase. These results indicate that the flow behavior of the reentrant nematic phase is essentially identical to that of the nem…
The thermal resistivity r(T) of ice Ih has been re-measured from 120K to as close as practicable to melting. Measurements were made under isobaric conditions at a pressure of 0.07 GPa, and corrected to isochoric conditions. The resultant deviation from the simple theoretical prediction, r/T=constant, has been plausibl…
The redox process of Co +z ions (z=2,3) substituted into the sapphire alpha -Al 2 O 3 structure produced by heat treatment in H 2 and O 2 atmosphere is correlated with ESR and ENDOR spectra of (Co +2 , H ) ) and with UV-VIS and IR spectra of Co +3 : alpha -Al 2 O 3 and (Co +2 , H + ): alpha -Al 2 O 3 respectively. Fro…