Materials Literature
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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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