Materials Literature
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A method for the numerical evaluation of N-beam diffraction amplitudes and intensities which has been successfully employed over the last few years is described. This derives from the multi-slice formulation of Cowley and Moodie. The physical basis of the method and practical approaches to calculation are described.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrical relaxation in a glass-forming molten saltF. S. Howell, R. A. Bose, P. B. Macedo, and C. T. MoynihanCite this: J. Phys. Chem. 1974, 78, 6, 639–648Publication Date (Print):March 1, 1974Publication History Published online1 May 2002Published inissue 1 March 1974https…
A theory of extinction is derived which is valid within the limit of the Darwin intensity transfer equations. An expression describing the effect of n-fold rescattering within an ideal crystallite is derived, which differs from the equation given by Zachariasen because independent coordinates x1 and x2 based on an ext…
Various lines of evidence are presented to show that for electrons in three-dimensional ordered systems there may be a regime intermediate between the extended states characteristic of weak disorder and the exponentially localized states characteristic of strong disorder. It is suggested that in the intermediate regim…
Abstract A comparison has been made between the reversible adsorption and the friction-reducing properties of long-chain fatty amines on stainless steel. This has shown that adsorption and lubricant failure depend on concentration of amine and temperature in a similar way. Breakdown of lubrication may therefore be ass…
The structure of a nickel–iodine boracite single crystal was investigated at 77 and 6 K by means of neutron diffraction. The high temperature phase at 77 K is characterized by the space group F43c, with statistical displacements of the metal and halogen ions out of the positions 24c and 8b respectively. Below 62 K the…
It is shown that in calcium sulphate (CaSO4) associates occur existing of a vanadate group on a sulphate-group site and a trivalent rare-earth ion on a calcium site. This system shows, therefore, interesting advantages for a study of energy transfer from the vanadate group to trivalent rare-earths ions. The vanadate e…
A single crystal EPR study of W5+ in triclinic Na0.33WO3, a recently discovered compound, has been carried out at about 15 K and 9.2 MHz. The EPR spectrum consists of two strong resonances and several weaker resonances whose relative intensities are sample-dependent. The total W5+ concentration is approximately 1000 a…
Two different forms have been proposed for the relation between the frequency-dependent dielectric constant of a polar substance and the autocorrelation function for the net dipole moment of a small spherical region inside the dielectric. We find that one of them is correct, while the other one describes a spherical s…
Molecular dynamics calculations have been carried out on the singlet distribution function (sdf) in hard-disk and hard-sphere solids. The dependence of the distribution function upon particle number and density and the deviations of this function from spherical symmetry are examined. The possible connection between th…
A Raman study of ferric chloride hexadydrate (FCHH) in 11.5M HCl solutions has shown the presence of tetrahedral FeCl4− ion as the most prominent species. An appreciable concentration of a polymeric species, which is composed of higher chloroferrate groups of the type FeCl5 · H2O, and a small concentration of lower ch…
Switching phenomenon in amorphous semiconductors is analyzed in an electrothermal model. Current-voltage characteristics are obtained from very general mathematical considerations concerning existence, uniquencess, local and global stability, and bifurcation of solutions of the nonlinear equations for temperatures and…
The ionization potentials of the gaseous atoms, monoxides, and dioxides over the refractory oxides of Ti, Zr, Hf, Th, U, Y, and La have been obtained from ionization efficiency curves and appearance potentials by electron impact. A method of simultaneous and intercomparative measurements with known standards was used.…
A study of the room-temperature infrared reflectance and Raman spectra has been made on a ${\mathrm{Ge}}_{0.30}$${\mathrm{S}}_{0.70}$ glass. The dominant features of the two spectra are complementary with respect to frequency, and can be understood in terms of a molecular model in which the Ge atoms are fourfold coord…
The heterogeneous oxidation of CO on epitaxially grown Pt(111) surfaces has been investigated using modulated molecular beam techniques. Within the range of pressures from 10−7 to 10−5 torr and temperatures from 450 to 950°K, the overall reaction is apparently first order. The observance of higher order kinetics in th…
The dispersion of the third order optical nonlinear polarizabilities of benzene, chlorobenzene, and nitrobenzene is measured in the vicinity of Raman active vibrations. Observation of interference between resonant and nonresonant contributions determines the magnitude and phase of the electronic hyperpolarizability. S…
Fine structure in the energy distribution of secondary electrons "back-scattered" from a graphite crystal surface is resolved and shown to be consequence of inelastic electron-electron scattering in which the dominant process is the population of final states above the vacuum level by electron-hole pair production via…
The ferroelectric phase transition in SnTe from a cubic to a rhombohedral structure at liquid-helium temperatures is investigated by Raman-scattering techniques. Using a backscattering geometry, Raman peaks are observed which correspond to $q\ensuremath{\simeq}0$ longitudinal-optical (LO) phonons in bulk $p=2.2\ifmmod…
The superconducting phase transition is predicted to be weakly first order, because of effects of the intrinsic fluctuating magnetic field, according to a Wilson-Fisher $\ensuremath{\epsilon}$-expansion analysis, as well as a generalized mean-field calculation appropriate to a type-I superconductor. Similar results ho…
Simple perturbation theory predicts that the lattice thermal conductivity should be inversely proportional to the absolute temperature. It is shown that the lattice thermal conductivity of minerals should not depart markedly from that variation, even when the average phonon mean free path is comparable to the lattice…