Materials Literature
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We discuss bias-induced threshold switching in chalcogenide-glass thin films, with an emphasis on the unique aspects of this phenomenon. The electronic nature of both the ON state and the recovery process is now clear. In this paper, we also establish the fundamentally electronic origin of the initiation process. An i…
Abstract A discussion of the general properties of the one‐dimensional electron density correlation function K ( z ) of a partially crystalline polymer with lamellar structure shows that application of a graphical extrapolation procedure permits direct determination of the crystallinity, the specific inner surface, an…
Some Elements of Mechanics. Effective Moduli: Spherical Inclusions. Effective Moduli: Cylindrical and Lamellar Systems. Bounds of Effective Moduli and Further Results. Laminates. Analysis, Strength, and Design. Wave Propagation. Inelastic and Non-linear Effects. Effective Thermal Properties. Index.
Ferroelectric smectic C (FSC) liquid crystals are used in a simple new geometry that allows the spontaneous formation of either of two surface-stabilized smectic C monodomains of opposite ferroelectric polarization. These domains are separated by well-defined walls which may be manipulated with an applied electric fie…
Our current understanding of catalysis on supported metals is reviewed, and the three most important problems still outstanding in this area of catalysts are discussed: 1) the sintering mechanism of the supported metals, 2) the structure and catalytic properties of small metallic crystals, and 3) catalysis by metal cl…
Nickel carbonyl [Ni(CO)(4)] is a toxic gas used in the manufacture of metallic nickel which has been shown to be carcinogenic and teratogenic in laboratory studies. Its decomposition in air proceeds at a rate that is strongly dependent on the concentration of carbon monoxide (CO). In the absence of CO, the lifetime in…
Three notable new developments in magnetic alloys are highlighted. These include rare earth-cobalt permanent magnets with maximum energy products up to 240 kilojoules per cubic meter; chromium-cobalt-iron permanent magnets that have magnetic properties similar to those of the Alnicos, but contain only about half as mu…
Fiber-reinforced composites are an emerging new class of engineering materials. The ability to tailor-make composite materials and structures offers exciting opportunities for a broad spectrum of industrial applications. This article reviews the nature of fiber-reinforced polymer composites, their characteristics and…
Recent research has shown that polymers, normally thought of as being insulators, exhibit a wide range of electrical conductive properties.
The unique properties of ceramics based on silicon carbide and silicon nitride make them prime candidates for use in advanced energy conversion systems. These compounds are the bases for broad families of engineering materials, whose properties are reviewed. The relationships between processing, microstructure, and pr…
Diamond or cubic boron nitride particles can be sintered into strong masses at high temperatures and very high pressures at which these crystalline forms are stable. Most of the desirable physical properties of the sintered masses, such as hardness and thermal conductivity, approach those of large single crystals; the…
Abstract The kinetics of hydrogen peroxide decomposition was followed in the presence of perchloric acid. The reaction was of second order with respect to the initial concentration of hydrogen peroxide and of first order with respect to the concentration of perchloric acid; the determined activation energy was 102.5 k…
Abstract A polyesterimide was prepared by reacting 4,4′‐diaminodiphenylmethane with trimellitic acid anhydride in ethylene glycol, which acts as an esterification reagent as well as a solvent. The solution and thermal behaviour, and a few other properties were studied. The polymer was found to be soluble in highly pol…
The aggregation of nitrogen in type Ib diamond, at 1500 degrees C in vacuo, has been investigated for natural and synthetic samples containing around 50 ppm and 500 ppm isolated substitutional nitrogen respectively. The rate constant for the aggregation process in untreated diamonds is very much less than that reporte…
Experimental results for the low temperature thermally stimulated luminescence of a single crystal ZnS specimen are presented. The analysis of these by conventional methods indicates the inadequacy of the basic single centre model. An extension of this model to include two overlapping states is developed and the exper…
Single crystals and polycrystalline Bi2WO6 samples are used to measure the dielectric constant, loss, and electrical conductivity, over a wide range of temperature, oxygen partial pressure in ambient atmosphere, and frequency of the measuring electric field. Maxima of the dielectric constant are observed at phase tran…
The behaviour of electron and hole quantum efficiencies as well as mobilities are investigated experimentally at high electric fields. The shape of transient small charge drift current as well as the field dependence of contributions of ionized electrons and holes to the quantum efficiency indicate impact interband io…
Measurements of the back scatter coefficient as a function of incident electron energy, angle of incidence, and target atomic number are described. The results are compared with existing theories for normal and non-normal electron incidence. Analytical expressions for the back scatter coefficient, which can be used in…
DC conductivity and dielectric studies of CoxZn1−xFe2O4 (x = 0.32, 0.49, 0.79), BaFe12O19, and Mg0.25Zn0.75Fe2O4 are reported as a function of temperature and frequency. The lattice constant and the existence of a single phase are established from X-ray studies. The dielectric behaviour is attributed to the Maxwell-Wa…
Highly oriented surface layers of lithium disilicate crystals were grown by crystallizing glasses of composition Li2Si2O5 in a temperature gradient. The polar c axes of the crystallites were oriented parallel to the temperature gradient and perpendicular to the sample surface. The pyroelectric response of the glass-ce…