Materials Literature
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An implicit finite difference method for the multidimensional Stefan problem is discussed. The classical problem with discontinuous enthalpy is replaced by an approximate Stefan problem with continuous piecewise linear enthalpy. An implicit time approximation reduces this formulation to a sequence of monotone elliptic…
The crystal structure of Pd 12.5 Y zeolite was determined before and after hydrogen reduction at different temperatures. When the zeolite is evacuated at 600°C, Pd 2+ ions are mainly found to occupy SI′ sites within the sodalite cages. Hydrogen adsorption at 25°C results in a complete withdrawal of Pd 2+ from SI′ site…
A review of the history, design, performance, and application of electret transducers is presented. Particular emphasis is placed on foil-electret transducers incorporating a thin-film electret made of Teflon or related materials. Such transducers have excellent frequency response, low distortion, small vibration sens…
This article presents in detail those results in ferromagnetic domain theory that have been obtained recently and have not previously appeared in monographs or reviews. A significant part of the article is devoted to consideration of basic problems of the theory. A detailed description is given of those properties of…
The fact that deformation and failure are facilitated by the reversible physico-chemical influence of the medium has been established by now for all types of solids: for metals (and also certain covalent crystals) in contact with liquid metals, for ionic crystals and inorganic glasses in the presence of molten salts,…
Low-temperature specific-heat and electrical-resistivity measurements show that the intermetallic compound ${\mathrm{Al}}_{10}$V has a local soft mode of characteristic temperature 22\ifmmode^\circ\else\textdegree\fi{}K. The behavior is well described by an Einstein model. The number of such modes, taken together with…
Longitudinal acoustic phonons have been measured by coherent inelastic neutron scattering in the direction of the platinum chains of a single crystal of the one-dimensional conductor ${\mathrm{K}}_{2}$Pt${(\mathrm{CN})}_{4}$${\mathrm{Br}}_{0.3}$\ifmmode\cdot\else\textperiodcentered\fi{}3${\mathrm{H}}_{2}$O at room tem…
The thermal conductivity of thin single crystals of silicon has been measured at room temperature and dry-ice temperature before and after neutron irradiation. It has been observed that, after irradiation, there is an appreciable boundary scattering effect for crystals of 20 mu m to 100 mu m thickness. The effect is s…
The electronic band structure of ferroelectric BaTiO3 is determined according to the Slater and Koster interpolation scheme (1954) with nonorthogonal orbitals. The effects of a phase transition on the energy levels are studied. Some integrated functions, such as the density of states, the joint density of states and t…
Abstract Brine solubility of calcium sulfate is a function of several variables, including brine composition, temperature, and the hydration state of the precipitating phase. Solubility data covering these variables is included, and the need for inclusion of an additional variable—turbulence—is shown for temperatures…
It is suggested in this paper that axisymmetric holes in thin sheets of fluid in which surface tension forces predominate will open out if they are initially large in relation to the thickness of the sheet; but that small holes will close up. No exact criterion has been found for the critical hole size in a free falli…
Polarized ${\ensuremath{\mu}}^{+}$ were stopped in Ni and Fe. The magnetic fields at the site of the muons, the initial polarization, and the depolarization time constant were obtained from 300 to 700\ifmmode^\circ\else\textdegree\fi{}K, i.e., through the Curie temperature of Ni. This experiment demonstrated that prec…
Single crystals of silver were cleaned by electron-and argon-ion bombardment under conditions of ultra-high vacuum. The work function of the (111) surface, measured photoelectrically, was (4.74 ± 0.02) eV. Oxygen adsorption caused an increase in the work function of about 0.4 eV.
The thermal conductivities of three large single crystals of zinc oxide have been measured, two from 3.5 to 300 K and one from 1.1 to 300 K. Two of the samples were hydrothermally grown and lithium doped, and one sample was vapor grown and undoped. The heat flow was parallel to the c-axis of one lithium-doped crystal…
Radiationless transitions in scheelite and fergusonite type crystals have been studied. It is shown that these transitions can be realized by virtual recharge for the ions having the tendency to form a tetravalent state (Pr3+, Tb3+). The probability of this process is greater than that of multi-phonon relaxation.
The tensor of elastic constants of MnAs in the ferromagnetic and paramagnetic states is evaluated from bending vibrations of straight and helical MnAs whiskers. The isotropic compressibility, predicted by the Bean-Rodbell model to be 4.6 × 10−12 dyn−1 cm2 and the same in both phases, is found experimentally to be (4.3…
The far infrared spectra of crystalline polytetrafluoroethylene has been obtained at temperatures above and below the 19°C phase transition. These measurements have shown, for the first time, the appearance of four lattice modes below 19°C at 42, 46, 55, and 84 cm−1. Upon cooling the lines become more intense and shif…
The lattice thermal conductivity between 1.7 and 270 K is reported for single crystals of mercury selenide having conduction electron concentrations from 2.1\ifmmode\times\else\texttimes\fi{}${10}^{17}$ to 6.7\ifmmode\times\else\texttimes\fi{}${10}^{18}$ ${\mathrm{cm}}^{\ensuremath{-}3}$. The most striking feature of…
Lattice vibrations of the hexagonal graphite crystal are analyzed using two-body carbon-carbon interaction potentials. The potential parameters are obtained from estimates of the long-wavelength frequencies of graphite and a knowledge of the nitrogen-nitrogen potential parameters. The dispersion relations along high-s…
The deformation potentials and $g$ values of the ground state of the boron acceptor in silicon have been determined from a study of the stress and Zeeman splitting of the electronic Raman scattering in this material. The stress splitting of the Raman line results from a twofold splitting of the ${\ensuremath{\Gamma}}_…