Materials Literature
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Dense self-bonded silicon carbide, prepared by impregnating with silicon pressed mixtures of silicon carbide and graphite, has been improved by attention to grading and composition. Treatment at 2000°C for ½ h has given a much greater degree of self-bonding. Porous self-bonded silicon carbide with a dense surface has…
The diamagnetic susceptibilities of some pyrolytic graphites deposited at 2100-2300\ifmmode^\circ\else\textdegree\fi{}C have been measured at room temperature. As-deposited samples had significantly larger susceptibilities than that of well-graphitized carbons or single-crystal graphite. Heat treatment at temperatures…
Based on conductivity, Hall effect, and magnetoresistance measurements an attempt is made to describe the behavior of current carriers in the layer planes of well-ordered pyrolytic graphite. The total carrier concentration decreases from approximately 11\ifmmode\times\else\texttimes\fi{}${10}^{18}$ ${\mathrm{cm}}^{\en…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUNUSUAL MAGNETIC PROPERTIES OF SOME SIX-COÖRDINATE COBALT(II) COMPLEXES1 —ELECTRONIC ISOMERSR. Carl Stoufer, Daryle H. Busch, and Wayne B. HadleyCite this: J. Am. Chem. Soc. 1961, 83, 17, 3732–3734Publication Date (Print):September 1, 1961Publication History Published online…
As part of a study of fabric drape, the fabric-shearing apparatus due to Mörner and Eeg-Olofsson has been built and studied. Methods of expressing the results are given and the variability of the results has been measured. The effect of tension on the specimen has been measured and a model is given which may be used t…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Crystal and Molecular Structure of S6 (Sulfur-6)Jerry Donohue, Aimery Caron, and Elihu GoldishCite this: J. Am. Chem. Soc. 1961, 83, 18, 3748–3751Publication Date (Print):September 1, 1961Publication History Published online1 May 2002Published inissue 1 September 1961htt…
The specimen independent infra-red absorption spectrum of diamond in the 2 μ to 6 μ region has been examined using a grating spectrometer. The results have been analysed in terms of multi-phonon processes. In particular the two-phonon absorption has been examined in detail in an attempt to deduce phonon energies for t…
A method is described for preparing silicon nitride bodies of almost theoretical density. Silicon nitride powder is hot pressed with a small proportion of catalyst, preferably magnesium oxide or nitride, at 1850°C. The bodies have very high flexural strength up to high temperatures, and preliminary measurements of cre…
The effect of hydrostatic pressure on the energy gap of Bi2Te3 has been investigated in the pressure range one to 30 000 atm. From resistivity measurements as a function of temperature and pressure, it has been determined that the energy gap decreases from 0.171 ev at one atmosphere to 0.104 ev at 30 000 atm, correspo…
A careful consideration on lattice vibrations in the ionic ferroelectric crystals such as BaTiO 3 reveals that a correct physical picture of the ferroelectric transition in these crystals may rather be regarded as an order-disorder transition of orientation of dipoles. A strong local order in the disordered phase is a…
Torsional modulus–temperature data have been obtained on heterogeneous polymer compositions prepared by several procedures. Both the state of aggregation of the component chain molecules and their degree of compatibility are significant variables. Modulus curves similar to those for crystalline polymers can be obtaine…
In Al-1·7 at. % Cu the critical resolved shear stresses, tension stress-strain curves, and the dependence of the flow stress on strain rate were determined from 4·2 to 273 or 373°K for the following structures: supersaturated α solid solution, α + GP I, α + GP II, α+ θ′, and α+θ. The difference between the CRSS at 4·2…
The photoionization of Ce3+ is investigated by determining the optical absorption changes and the electron spin resonance changes that occur when cerium-containing silicate glasses are illuminated with ultraviolet light. The results are: (1) The room temperature quantum yield of photoelectrons from Ce3+ is 0.1. (2) Th…
The electrical conductivity of nickel oxide has been studied at temperatures between 600° and 1350°C and partial pressures of oxygen between 1 atm and 10−4 atm. The slope of log conductivity vs reciprocal temperature plots increases when the temperature is high enough for the sample to come into thermodynamic equilibr…
Abstract Various theories accounting for the existence of a front factor in the equation of state for rubber elasticity are reviwed. It is shown that a front factor which may be different from unity exists whether or not intramolecular energy effects are present. A unified theory is presented which is applicable both…
Abstract The nonisothermal method of Freeman and Carroll is used to investigate the kinetics of the thermal degradation of polyethylene and polystyrene. The reactions were studied thermogravimetrically under a vacuum of 1 mm Hg. Decomposition appears to occur in stages. The rate parameters were determined for each reg…
The theory of sound attenuation in structurally perfect dielectric crystals is extended and applied to recent experiments on the absorption of acoustic waves in crystalline quartz at frequencies from ${10}^{9}$ cps to 2.4\ifmmode\times\else\texttimes\fi{}${10}^{10}$ cps. The sound wave is assumed to vary the frequenci…
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