Materials Literature
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The validity of the zero differential overlap approximation is investigated by means of a systematic expansion in terms of a parameter of the order of magnitude of a typical overlap integral between neighboring atoms. The terms of the Fock operator in a basis of orthogonal atomic orbitals can be arranged after differe…
The band structure of metallic face-centered cubic TiC, TiN, and TiO has been obtained by the augmented-plane-wave (APW) method at the equivalent of 256 points in the Brillouin zone and for an energy range appropriate to cover the nonmetal $2s$ and $2p$ and the titanium $3d$ and $4s$ states. A density of states, the F…
Control of oxygen fugacities in a CO + CO atmosphere has been established experimentally by using a solid-phase buffer technique. Equilibration between the buffer and the enclosed sample is established by diffusion of the gas atmosphere through the buffer. The establishment of equilibrium by this method is indicated b…
Received 13 January 1965DOI:https://doi.org/10.1103/PhysRevLett.14.390©1965 American Physical Society
In addition to the GRI and uv bands induced in all diamond by 0.78-MeV electron irradiation, another optical absorption feature, which we have named the ND1 band, is found in all Type I diamonds. A single EPR line appears to be associated with the ND1 band. It is suggested that the ND1 center arises from the combinati…
The thermal stability of siderite (FeCO(3)) was studied by two independent methods in which the oxygen fugacity of the gas phase was controlled by equilibration with graphite. Both series of experiments indicate that siderite decomposes stably to magnetite + graphite between 455 degrees and 465 degrees C at 500 to 200…
The long-chain nature of the polymer molecule, together with the usual broad distribution of molecular lengths, makes it kinetically very unlikely that the molecule will achieve, on crystallization, its thermodynamically most stable form. Under most crystallization conditions a large portion of the polymer molecules c…
Received 2 February 1965DOI:https://doi.org/10.1103/PhysRevLett.14.360©1965 American Physical Society
Abstract An efficient gas absorption device has been developed based on a stable aqueous foam moving in a horizontal duct, with a gas‐liquid interaction that causes only negligible pressure drops. The study of a liquid‐phase and a mostly gas‐phase‐controlled system has indicated that their mass transfer performance ca…
Using a drop method and an ice calorimeter, precise measurements of enthalpy relative to 0 °C were made on a sample of granular polytetrafluoroethylene which was initially 95 percent crystalline. The measurements were at temperatures every 50 degrees from 50 to 300 °C (both before and after melting and quenching); and…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStudies on Adsorption of Oxygen on γ-Alumina. Nature of Adsorbed Species1L. N. Mulay and L. K. KeysCite this: J. Am. Chem. Soc. 1965, 87, 6, 1192–1195Publication Date (Print):March 1, 1965Publication History Published online1 May 2002Published inissue 1 March 1965https://pub…
Summary Uvarovite and its relationships with grossular and andradite have been studied in order to understand better the geochemistry of uvarovite. Synthese have been carried out under both dry and hydrothermal conditions; a solid solution with grossular was obtained under both conditions, but with andradite only unde…
The elastic displacement of screw dislocations bounding the lamellar grains is of the correct order of magnitude to account for the observed elasticity of reactor grade graphite. The change of elastic modulus on irradiation cannot be explained in terms of the pinning of these or of other dislocations by the clusters o…
Summary The transformation of manganite during heating has been studied by single crystal X-ray diffraction methods. It is observed that manganite transforms into pyrolusite keeping its original axial directions parallel to those of the transformed phase. Pyrolusite then transforms into Mn 2 O 3 with its [001] ‖ [110]…
An experimental investigation of the effects of temperature and grain size on the tensile properties of high purity molybdenum showed that transitions from ductile to brittle behaviour occur with both decreasing temperature and increasing grain size. Based on the assumed temperature-independence of the critical stress…
Magnetic structure of single crystal of Fe2As, which corresponds to C38 type of crystal structure, the same as that of Mn2Sb, has been determined by neutron diffraction method. The crystal is antiferromagnetic with the Néel temperature of approximately 50°C. A series of (00l)-type reflections at room temperature revea…
Infrared transmission of NiCr2O4 and MnCr2O4 powder was measured from 15 to 500 μ and at 100°–400°K. Four absorption peaks were discovered at ∼600, ∼500, ∼400, and ∼200 cm−1. The peak near 200 cm−1 of NiCr2O4 showed a shift with temperature which is apparently proportional to the change of c/a, while the width remaine…
The kinetics of formation at 900°C of the fcc γ phase have been studied metallographically in Alnico 8 alloys with Cu contents from 0.01 to 3.34 at. %. Increasing Cu content is found to increase the gamma-forming tendency. Selected two-phase specimens subjected to electron microprobe analysis showed a systematic deple…
A single parameter is suggested to account for the complicated stress and strain distributions in two-phase materials. Its existence requires verification from extensive experimental studies.
Abstract The distributions of short‐chain branching in some commercial low‐density polyethylenes have been investigated by measuring the degree of short‐chain branching of their fractionated samples. The results obtained on the fractions which were fractionated with respect to molecular weight showed that some polyeth…