Showing papers in "Journal of Physics and Chemistry of Solids in 1976"

TL;DR: In this article, it is shown that there is significant and unexplained disagreement between the value of the low temperature specific heat Debye temperature of NbSe2 and the value determined on the basis of the elastic constants, but that the model predictions of c33 and c44 are in satisfactory agreement with the values extracted from the neutron data for both MoS2, and NbSE2.

TL;DR: In this paper, the exciton absorption peak in a III-V ternary alloy was observed and the most accurate determination of both the composition dependence of the Γ band gap and the position of the X crossover was made.

TL;DR: In this paper, the intensity distribution of inelastically scattered thermal and hot neutrons on hydrogen impurities in α-palladium hydride has been studied as a function of concentration, temperature, momentum transfer and different annealing procedures.

TL;DR: In this article, the diffusive motion of silver ions in σ-AgI at 250°C has been studied by quasielastic cold neutron scattering, and the model closely fits the data.

TL;DR: In this paper, electron and hole-drift velocity is measured in the layer semiconductors HgI2, GaSe, PbI2 and GaS, mainly on the direction parallel to the c-axis between 80 and 400 K.

TL;DR: In this article, the second-order elastic constants and their temperature and pressure derivatives have been measured for four AgBr-AgCl mixed crystals, with 19.5, 39.1, 56.6 and 78.7 mole % AgCl, using the ultrasonic pulse-echo technique at room temperature.

TL;DR: In this article, the authors used the basic assumptions of the Bragg-Williams description of order-disorder alloys to develop an equation giving the temperature dependence of the diffusion coefficient of iron both above and below the Curie temperature as a function of the activation energy of diffusion in the paramagnetic range.

TL;DR: In this article, the Coulomb, van der Waals and repulsive lattice sums occurring in the higher order elastic constants up to sixth order have been calculated for the rocksalt and cesium chloride structures.

TL;DR: In this article, the experimental data of Anderson, Fugate and Swenson for the rare gas solids are recast in a dimensionless form which exhibits the close approach to the Lennard-Jones form except at the highest temperatures, and also in a form derived from the theory of finite elasticity.

TL;DR: In this paper, the free energy is written as Taylor series in E, the invariant analogue of the Eulerian strain tensor, or η, the Lagrangian tensor.

TL;DR: In this article, the energy levels for Ho3+ in single crystal LiYF4 from 0-21,300 cm−1 have been determined from polarized absorption and fluorescence spectra using crystals at temperatures between 4 and 300°K.

TL;DR: In this article, a calculation of the formation energy and volume for a vacancy in transition metals is presented, using a tight binding scheme for the d band and a Born-Mayer type potential to account for the repulsive part of the energy at small distances.

TL;DR: In this paper, the Gruneisen ratio of crystalline solids is shown to be dependent on a parameter n whose values are characteristic of each solid, and can be determined by two independent ways: from experimental shock data and from the pressure derivative of Poisson's ratio.

TL;DR: The three body force shell model (TSM) has been applied to evaluate the magnitude of the pressure derivatives of second order elastic constants of alkaline earth oxides and a good agreement with the experimental values has been obtained as mentioned in this paper.

TL;DR: In this article, the authors measured sulphur fugacities in equilibrium with Fe 1− x S (pyrrhotite) at different temperatures in the range 820-1374 K by direct (silica gauges) and indirect (H 2 S/H 2 ) methods.

TL;DR: In this paper, the atomic defect structure of nonstoichiometric ceria was studied by means of X-ray diffraction and it was observed that the lattice expands as a function of increasing defect concentration and exhibits only fluorite-like diffraction peaks.

TL;DR: Mossbauer spectra have been obtained for the cobalt-iron spinels having the general formula COxFe3−xO4 for the whole range of composition, materials from x = 0 to x = 2.76 having been studied as discussed by the authors.

TL;DR: In this paper, the repulsion between ions is postulated to be due to the increase in the internal energy of the ions arising from the distortion and the compression at the points of contact with their neighbours.

TL;DR: In this article, the Curie temperature and ordered magnetic moment of Y6Mn 23 and Y 6 Fe 23 were determined for ternaries represented by the formula Y 6 (Fe 1− x Mn x ) 23.

TL;DR: In this article, the relative merits of these two extreme models are discussed, and the results are examined on the basis of two models, i.e., a competition between the Fe3+ ions and the cobalt ions for the two sites; while for the other there is a competition among Fe3+, ions and Co2+ ions.

TL;DR: In this article, single crystals of yttrium boride YBn with n = 61 ± 3 were grown from the melt and measurements of elastic constants, acoustic attenuation, electrical resistivity and optical absorption were presented.

TL;DR: In this paper, a dynamic method for studying the diffusion of oxygen vacancies by measurements of the time dependence of the electrical conduction after a change in the oxygen partial pressure has taken place was discussed.

TL;DR: In this article, an explicit mathematical description for the Gruneisen parameter and adiabatic compressibility of solids is provided, and the final results turn out to be of considerable simplicity and generality.

TL;DR: In this paper, the lattice term, C L was obtained from the C P data of LuAl 2 by a method of interpolation which gave values of C L for an arbitrary R Al 2 compound.

TL;DR: In this article, the authors examined the nature of phase transitions which arise from two classes of phenomenological models for the free energy of ionic crystals containing Prenkel disorder of one constitutent.

TL;DR: In this paper, the phase diagram Co-S has been complemented in terms of interacting cobalt vacancies and additional defects near to the cobalt rich boundary of the homogeneity range were not detected.

TL;DR: The self diffusion of Li 7 in near stoichiometric LiAl has been investigated by observing the Li 7 and Al 27 NMR relaxation rates as mentioned in this paper, and the diffusivity for a Li 7 atom is determined to be D = 9 × 10 −6 exp (−0.12 eV/kT) cm 2 /sec.

TL;DR: In this paper, the adiabatic elastic stiffness constants of indium and lead were measured from room temperature to their respective melting points using the ultrasonic pulse-echo method.

TL;DR: In this paper, the magnetites are substituees a l'aluminium and au chrome presentent vis a vis de la magnetite pure une forte diminution de conductivite en meme temps qu'un changement de type de conduction sous vide quand on passe du spinelle inverse au spinelle normal lors de the substitution.