Effect of a third component on ordering of substitutional alloys with anisotropic interatomic interactions

The problem of third-component impurity effects on ordering processes in alloys with anisotropic interatomic interactions is treated in the quasichemical approximation. The case of low-impurity concentration is investigated in detail. It is shown that the presence of a third component leads to an anisotropic redistribution of atom pairs of different types over the various crystal directions even when it interacts isotropically with the main components. The nature of this redistribution depends on alloy composition. The magnetic anisotropy constant of a ternary alloy, induced by thermomagnetic processing, is calculated, and its concentration and temperature dependence are found.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No.7, pp.32–37, July, 1975.     

Disproportionation of condensed thiopyrans with trifluoroacetic and deuterotrifluoroacetic acids

The disproportionation of isomeric 2,4-diphenyl-5,6-tetramethylene-4H-thiopyran,-6H-thiopyran, and 2,4-diphenyl-5,6,7,9-tetrahydrothiochromene with trifluoroacetic and deuterotrifluoroacetic acids was investigated for the first time. The direction of protonation of the sulfides was established, and this made it possible to form a judgment regarding the structure of the intermediate carbonium ions, which are hydride-ion acceptors. The correctness of the mechanism of disproportionation of condensed two-ring sulfides with a 4H-thiopyran ring was proved. A mechanism for the disproportionation of isomeric 2,4-diphenyl-5,6-tetramethyl-6H-thiopyran and 2,4-dipheny1-5,6,7,9-tetrahydrothiochromene was proposed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1338–1341, October, 1981.     

Two-generator Discrete Subgroups of Isom(H2) Containing Orientation-reversing Elements

Let f and g be elements of the isometry group Isom(H²) of the hyperbolic plane H², and assume that one of them is orientation-reversing. We determine when the group (f,g) they generate is discrete; in particular, we obtain the classification of such groups. As an application to knot theory, we completely determine the tunnel number one Montesinos knots.     

Electrophysical properties and energetical spectrum of heteroepitaxial germanium films

An epitaxial growth of Ge films from molecular beam is characterized by thermodynamical nonequilibrium. This leads to formation of numerous structural defects connected with local levels in the band gap (mainly acceptor-type). Depending on the deposition temperature the density of such levels may change in wide range (10¹⁶–10¹⁸ cm^?3). This determines various mechanisms of impurity conduction. The tails of the density of states in the band gap are also connected with the defect structure of the films. Stresses in heteroepitaxial Ge films result in the splitting of the valence band atk = 0 and in a change of the band gap. Thus, these stresses have influence on the electrical and optical properties of the films.