Journal•ISSN: 0022-3697

# Journal of Physics and Chemistry of Solids

About: Journal of Physics and Chemistry of Solids is an academic journal. The journal publishes majorly in the area(s): Band gap & Electrical resistivity and conductivity. It has an ISSN identifier of 0022-3697. Over the lifetime, 18045 publication(s) have been published receiving 420510 citation(s).

Topics: Band gap, Electrical resistivity and conductivity, Raman spectroscopy, Phase transition, Dielectric

##### Papers

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Abstract: An analysis is made of the process whereby diffusion effects can cause the precipitation of grains of a second phase in a supersaturated solid solution. The kinetics of this type of grain growth are examined in detail. Some grains grow, only to be later dissolved; others increase in size and incorporate further grains that they encounter in so doing. This latter phenomenon of coalescence is discussed in a new “kinetic” approximation. Formulae are given for the asymptotic grain size distribution, for the number of grains per unit volume and for the supersaturation as a function of time. The effects of anisotropy, strain, crystalline order and the finite size of the specimen are allowed for. It is pointed out that for a material that can be said to be “supersaturated with vacancies”, the discussion can be applied to the vacancies as solute “atoms” which cluster together to form internal cavities. The practical case of a real, finite crystal is here important, because the vacancies can in general also escape to the surface. A special analysis is made of this example, and the results are applied to the theory of sintering.

6,470 citations

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Abstract: A thermodynamic theory of “weak” ferromagnetism of α-Fe 2 O 3 , MnCO 3 and CoCO 3 is developed on the basis of landau's theory of phase transitions of the second kind. It is shown that the “weak” ferromagnetism is due to the relativistic spin-lattice and the magnetic dipole interactions. A strong dependence of the properties of “weak” ferromagnetics on the magnetic crystalline symmetry is noted and the behaviour of these ferromagnetics in a magnetic field is studied.

3,916 citations

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Abstract: The band structure of InSb is calculated using the k ·. p perturbation approach and assuming that the conduction and valence band extrema are at k = 0. The small band gap requires an accurate treatment of conduction and valence band interactions while higher bands are treated by perturbation theory. A highly nonparabolic conduction band is found. The valence band is quite similar to germanium. Energy terms linear in k which cannot exist in germanium are estimated and found to be small, though possibly of importance at liquid-helium temperature. An absolute calculation of the fundamental optical absorption is made using the cyclotron resonance mass for n-type InSb. The agreement with experimental data for the fundamental absorption and its dependence on n-type impurity concentration is quite good. This evidence supports the assumptions made concerning the band structure.

2,794 citations

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Abstract: The relation between the symmetry of electron orbitals and superexchange interaction is discussed. It is shown that the sign of the superexchange interaction is closely connected with the cation orbital state, when the cation is subject to the crystalline field arising from octahedrally or tetrahedrally surrounding anions. In some cases, the sign of the superexchange interaction is definitely determined from the symmetry relations. The cases in which each cation is subject to an octahedral cubic field and the lines connecting the interacting cations to the intervening anion make an angle of either 180° or 90° are discussed in particular. Our discussion of the 180° case is applicable to crystals of the perovskite type and NaCl type and that of the 90° case to anhydrous chlorides. In the case where each cation is subject to a tetrahedral cubic field, there is a definite relation between the symmetry of the cation electron orbitals and superexchange interaction, if only the s -orbital of anion participates in the superexchange interaction. TiH 2 is an example of this case. The interaction between nearest-neighbor cations in the crystal of the NaCl type is also discussed.

2,108 citations

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Abstract: The Reuss-Voigt approximations are well known methods whereby the isotropic polycrystalline elastic constants can be calculated from the single crystal elastic constants. It is shown here that the Reuss and the Voigt approximations can be used to estimate, accurately, the mean sound velocity of a crystal. Using this method, the Debye Temperature, which is proportioned to the mean sound velocity, can be determined without recourse to the published tables or high speed computers. This approximation is valid for all crystal classes.

2,072 citations