Materials Literature
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The sintering behavior of primarily covalently bonded β‐SiC, Si, and Si 3 N 4 was studied using surface area and densification measurements as well as observations of microstructures developed during firing. The existence of highly dense, microscopic regions and large (≥100°) dihedral angles in fired compacts of β‐SiC…
A review of the luminescence properties of amorphous semiconductors is presented. The materials covered are chalcogenide glasses, silicon and arsenic. Luminescence spectra, excitation spectra, temperature dependences and lifetimes are described. The radiative transition in chalcogenides is the recombination of an elec…
Constitutive relations for metal nonelastic deformation are proposed. The descriptiion is entirely in terms of real time strain rate. The equations are fully three-dimensional, and the description is incremental. Changes of loading direction are treated in a simple manner. The current deformation state of the metal is…
Displacive phase transitions and phase transitions of the type disorder-order usually result in symmetry changes such that the space groups of both structures are related as group and subgroup. The subgroups of a space group always belong to one of the following three types: they have either the same primitive cell as…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular stereochemistry of two intermediate-spin complexes. Iron(II) phthalocyanine and manganese(II) phthalocyanineJohn F. Kirner, W. Dow, and W. Robert. ScheidtCite this: Inorg. Chem. 1976, 15, 7, 1685–1690Publication Date (Print):July 1, 1976Publication History Publishe…
The one-electron density function for a group of atoms within the asymmetric region of a unit cell is represented by a finite multipole expansion of the charge density about each atomic center. Each atomic expansion is called a pseudoatom. If the pseudoatom charge density is effectively rigid with nuclear motion, then…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA surface study of cobalt-molybdena-alumina catalysts using x-ray photoelectron spectroscopyThomas A. Patterson, James C. Carver, Donald E. Leyden, and David M. HerculesCite this: J. Phys. Chem. 1976, 80, 15, 1700–1708Publication Date (Print):July 1, 1976Publication History…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEvaluation of candidate solids for high-temperature desulfurization of low-Btu gasesPhillip R. Westmoreland and Douglas P. HarrisonCite this: Environ. Sci. Technol. 1976, 10, 7, 659–661Publication Date (Print):July 1, 1976Publication History Published online1 May 2002Publish…
Abstract Since the first intensive literature review on silicas and silicates was published, significant new technology for their use in rubber has developed. Usage in the rubber industry has broadened considerably, and increases in their consumption have occurred during the ensuing fifteen years. From the “soles and…
Polysulfone has been sulfonated to varying degrees using a sulfur trioxide–triethyl phosphate complex as the sulfonating agent. These conditions are suitable for surface sulfonation as well as solution sulfonation. The neutralized, sodium salt form is much more stable than the free acid form. The glass transition temp…
A description is given of a method for growing chromium-activated yttrium aluminum garnet crystals. The results are reported of an investigation of the influence of chromium concentration from 0.01 to 1.0 wt.% on the absorption and luminescence spectra of garnet crystals. Broadening and short-wavelength shift of the R…
Pervasive alteration is a common feature of metamict minerals. Previous studies of metamict niobium-tantalum-titanium oxides and electron microprobe analyses of altered areas in metamict yttrialite document the leaching of uranium, thorium, and rare earth elements. These data suggest that glasses may not provide a sta…
Over 300 small-scale experiments have been performed to investigate the interaction that sometimes occurs when hot liquid metal is poured into a container of water. IN these experiments molten tin was used. The violence of each interaction was classified by measuring the ratio of the mass of comminuted tin to the orig…
The crystal structure of (CH3NH3)2MnCl4 (MAMC) is determined by neutron diffraction at 188 K in the low temperature tetragonal phase (P42/ncm). The sequence of structural phase transitions of MAMC can be discussed in terms of NH …︁ Cl bridges between NH3 and certain Cl−-ions. The order of the room temperature orthorh…
The $\ensuremath{\omega}$ phase transformation in Zr-Nb alloys has been studied by measuring x-ray and M\"ossbauer diffuse scattering from single crystals with compositions ranging from 8- to 30-wt% Nb. We present an extensive two-dimensional mapping of the x-ray diffuse scattering for all compositions. The distinct f…
Mean free paths for electrons in bulk jellium are calculated for electrons with energies from a few hundred to a few thousand eV and for values of ${r}_{s}$ for 1.5 to 5 where ${r}_{s}$ is the average distance between valence electrons measured in units of the Bohr radius. Account is taken of exchange and correlation…
Optical absorption, reflectivity, and photoconductivity in the near-uv range (1950-3200 \AA{}) of a thin film of hexagonal boron nitride were measured. The main absorption peak was observed at 6.2 eV. A sharp fall at about 5.8 eV was attributed to the direct band gap. The temperature dependence of the band gap was fou…
It is pointed out that the recent observation of localized holes and electrons at low temperatures after optical excitation of chalcogenide glasses by Bishop et al. is consistent with a model previously proposed for lone-pair amorphous semiconductors. The model uses the existence of these localized states to provide a…
Abstract Mit Hilfe der Röntgendiffraktometrie werden die Phasengleichgewichte des Systems MgO ‐MgC12 ‐ H 2 Obei 25°C sowie die Reaktionen, die zur Bildung der Gleichgewichtsphasen 5 Mg(OH)2°C MgClg ° 8 H 2 O und 3 Mg(OH)2°C MgClg ° 8 H 2 O führen, untersucht.
From light scattered by director modes in the smectic-$A$ phase of cyanobenzylidene octyloxyaniline (CBOOA) and octyloxy cyanobiphenyl (80CB) we deduce that the restoring force for phase fluctuations in the smectic order parameter vanishes as ${({T}_{c}\ensuremath{-}T)}^{0.33}$ as the nematic phase is approached. In C…