Materials Literature
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Velocities of propagation of high-frequency ultrasonic waves and the adiabatic elastic moduli for single-crystal gallium arsenide are reported. Data at 25°C were obtained in the range of 20–180 mc/sec. The elastic moduli based on a density of 5.307 g/cm3 in units of 1012 dynes/cm2 are c11 = 1.188±0.14%; c12 = 0.538±0.…
The lattice spacing of cubic barium titanate (BaTiO 3 ) has been measured as a function of temperature by means of a Unicam X-ray camera. The relation between a 0 (in Å) and t between 350 °C and 1050 °C is:[Formula: see text]The maximum systematic error in a 0 is 0.0005 Å. The linear expansion coefficient varies in an…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSaturation Magnetizations of Iron Carbides1L. J. E. Hofer and Ernst M. CohnCite this: J. Am. Chem. Soc. 1959, 81, 7, 1576–1582Publication Date (Print):April 1, 1959Publication History Published online1 May 2002Published inissue 1 April 1959https://pubs.acs.org/doi/10.1021/ja…
Experiments by transmission electron microscopy on thin foils of polycrystalline A1-4 % Cu alloys, quenched from various temperatures have revealed helical dislocation lines which are thought to be produced by condensation of vacancies on dislocations of predominantly screw character. The axes of the helices are paral…
Abstract Polyethylene oxide and atactic and isotactic polypropylene oxides were pyrolyzed in a vacuum in the temperature range 265 to 363°C. One phase of the investigation consisted in fractionating the products of degradation and analyzing the fractions qualitatively and quantitatively. Another phase consisted in mea…
Micropowders of stoichiometric copper, nickel, and cobalt ferrites were prepared by low temperature (<800°C) treatment of the coprecipitated metal oxalates. The magnetic properties of each ferrite were determined as functions of particle or crystallite size in the range from 70 to >2000 A. Particle sizes…
The axial thermal‐expansion coefficients of β‐eucryptite have been measured and correlated with the volume expansion of an aggregate measured dilatometrically. A mechanical analogy to the structure of β‐eucryptite is suggested which may explain the pronounced thermal contraction in the c direction.
Abstract With three polymers widely different in polarity—polyethylene terephthalate, polyethylene, and nylon 610—the water vapor permeability P of unoriented films has been shown to increase as the amorphous fraction X a is increased, following the relation P = P a X a 2 . For polyethylenes, adherence to this relatio…
An experimental investigation was made at elevated temperatures and pressures of the hydrolysis of K-feldspar to mica+silica and of mica to kaolinite. Values of the equilibrium quotient, m <sub>KCl</sub> /m <sub>HCl</sub> , were determined at temperatures ranging from 200 degrees to 550 degrees C. The solution pressur…
The concept of octahedral site preference energy in spinels has been extended to include Madelung and short-ranged as well as crystal field terms. A set of site preference energies is formulated which can be used to predict the ionic distribution of spinels involving the nontransition as well as the transition ions. T…
Mechanical relaxation measurements are used extensively to obtain information on the diffusion rate of interstitial solute atoms in body-centered cubic metals. Such studies have been stimulated by a model, developed by J. L. Snoek, which yielded a relationship between a relaxation time, an experimental parameter, and…
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Methods of preparation and results of measurements of the dielectric constant of solid-solution single crystals of KNb${\mathrm{O}}_{3}$ and KTa${\mathrm{O}}_{3}$ are presented. Data are given for the composition range 0-80 mole percent KTa${\mathrm{O}}_{3}$ in the temperature interval -180\ifmmode^\circ\else\textdegr…
The influence of temperature and strain rate on the flow stress of polycrystalline aluminium, and single crystals of aluminium, copper and silver was studied. Tensile tests were carried out at various temperatures down to 1.7°K. The results indicate that the reversible change of flow stress (after correction for varia…
Diffraction patterns obtained from atomically clean germanium surfaces contained half-integral order beams in (110) azimuths for both (100) and (110) surfaces and in all azimuths for the (111) surface. These results are considered to be due to displacements of surface atoms from their normal bulk lattice positions in…
Abstract The dissociation of hydrogen at a tungsten filament has been studied in the temperature range 1200 to 1800°K and at pressures between 10-2 and 10-6 mm. The results obtained differ from those found in the literature and it is shown that this is because the surfaces employed by previous workers were contaminate…