Structure and properties of antimony-doped potassium titanyl phosphate single crystals

Antimony-doped potassium titanyl phosphate (KTP) crystals of the composition KTiOPO₄ are studied by X-ray diffraction analysis. It is shown that, with an increase of antimony content in KTP crystals, the occupancies of potassium positions change and new additional positions for potassium atoms arise. The formation of additional vacancies and splitting of the potassium-cation positions explain the considerable decrease in the temperature of the ferroelectric phase transition, enhancement of the relaxation phenomena, and an increase in electric conductivity of antimony-doped KTP crystals. Substitution of antimony atoms for titanium is accompanied by elongation of short and shortening of long Ti-O bonds in the TiO₆ octahedra, processes which result in lower intensity of second-harmonic generation in laser-irradiated KTP crystals.     

Unusual dependence of the effectiveness of spectral sensitization of the photoconductivity of polycrystalline ZnO on the dye concentration in a mixed monolayer on a semiconductor surface

A nonmonotonic, oscillatory dependence of the effectiveness of spectral sensitization of the photoconductivity of polycrystalline ZnO on the dye concentration in n-octadecylamine and stearic acid monolayers, transferred to the surface of a semiconductor by the Langmuir-Blodgett method, has been observed experimentally. The observed effect is completely different from the monotonic increase of the photocurrent with a peak at some dye concentration in certain films adsorbed on a semiconductor surface from a solution and in films deposited in vacuum. To explain the results, a simple model describing the balance of monomers and dimers of the dye is examined. The solution of the problem is an oscillatory decaying function of the monomer concentration as the total dye concentration in the monolayer increases. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 3, 174–177 (10 August 1996)     

Study of the process of unstable flow of elastomers in open and closed channels and its connection with mechanical characteristics of the material

The unstable flow process has been studied for examples of a series of unvulcanized rubbers of different structures by a complex of methods — capillary, tribometric, and dynamic methods. A connection has been found between the critical parameters which characterize the onset of this process and the dynamic mechanical characteristics. The possibility of modeling the unstable flow process in open channels is shown.A. V. Topchiev Institute for Petrochemical Synthesis, Academy of Sciences of the USSR, Moscow. Translated from Mekhanika Polimerov, No. 3, pp. 530–536, May–June, 1970.     

Crystal and molecular structure of 2-(p-tolylimino)-4-methyl-4-ethyl-5-methylenethiazolidine

It was found by an x-ray diffraction study of 2-(p-tolylimino)-4-methyl-4-ethyl-5-methylenethiazolidine that the thiazolidine molecules in the crystal are joined together to form centrosymmetric dimers due to the formation of N-H...N hydrogen bonds. The structure of the dimer and the bond lengths and angles of the thiazolidine are presented. The study confirmed the imino structure of the investigated compound. The pathway of fragmentation of the alkyl groups attached to C₄ during mass-spectroscopic analysis was analyzed thoroughly.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1617–1619, December, 1981.     

A product of the reaction of bis(methylcarboranyl)chlorophosphine with methylcarboranyllithium

Conclusions 1. An x-ray crystallographic structural study has shown that each phosphorus atom in penta(methyl-o-carboranyl)diphosphine is attached to two o-carboranyl rings directly through a carboranyl carbon atom, while the third ring is attached through a methylene group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2346–2348, October, 1979.The authors thank V. F. Sizyi and Yu. S. Nekrasov for taking and interpreting the mass spectra.