Structural phase transitions in Cu2–xFeyS crystals

Crystals with Cu_2−xFe_yS compositions (x = 0.30, 0.25, 0.20, 0.15; y = 0.05) have been synthetized and obtained by the method of slow cooling. X-ray diffractometric studies have shown that at room temperature the above crystals consist of an orthorhombic phase (anilite), a monoclinic phase (djurlite), and their metastable high-temperature facecentered cubic phases (FCC)₁ and (FCC)₂, respectively. A crystallographic relation has been found between the lattices of the orthorhombic, monoclinic and (FCC)₁ phase. It is shown that all these phases transform in the final analysis to a single high-temperature fcc phase. All the transitions are reversible, i.e. in the course of inverse cooling to room temperature, the diffraction patterns are restored completely in reverse order.     

The Ga2S3?;Eu2O2S System

By the methods of differential thermal, high-temperature differential thermal, X-ray phase shift, microstructural analyses and also by the measurement of microhardness and density interactions in Ga₂S₃? ;Eu₂O₂S system have been investigated. The existence of three new phases of composition (EuO)₂Ga₄S₇, EuGaOS₂, (EuO)₄Ga₂S₅ has been revealed in the system. The eutectic coordinates correspond to 12 mole-% of Eu₂O₂S and 1210 K. The solubility on the basis of Ga₂S₃ at 295 K reaches 1 mole-% of Eu₂O₂S.     

Preparation of a Polymer via Condensation of <Emphasis Type="Italic">o</Emphasis>-Phenylenediamine with <Emphasis Type="Italic">p</Emphasis>-Xylylene Dibromide and Its Properties

Condensation of para-dibromoxylene and ortho-phenylenediamine in glass ampule at 150°С in an alkaline aqueous solution has yielded polymer with completely substituted N–H hydrogen atoms, capable of formation of polymeric cation-radicals. Complexes of this polymer and N,N,N',N'-tetrabenzyl-o-phenylenediamine with Co(II), Ni(II), Cu(II), and Ag(I) have been obtained, and their structure has been studied.     

Analysis of mixed problems of matching in hyperbolic systems of different orders

A mixed problem of matching in hyperbolic systems of different orders with irregular boundary conditions is considered. In particular, these systems include hyperbolic systems with coefficients having discontinuities of the first kind. Under certain conditions, an analytical representation of the solution of the problem is obtained by means of a finite integral transform.     

Alkylation of β-dicarbonyl compounds with 1,2-dibromocyclohexane

Alkylation of acetylacetone, ethyl acetoacetate, and diethyl malonate with 1,2-dibromocyclohexane in the presence of K₂CO₃ in DMSO occurs only asC-alkylation accompanied by dehydrobromination, whereas a similar reaction of dimedone follows bothC- andO-alkylation pathways. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 317–319, February, 1998.     

Application of generalized separation of variables to solving mixed problems with irregular boundary conditions

One of the methods for solving mixed problems is the classical separation of variables (the Fourier method). If the boundary conditions of the mixed problem are irregular, this method, generally speaking, is not applicable. In the present paper, a generalized separation of variables and a way of application of this method to solving some mixed problems with irregular boundary conditions are proposed. Analytical representation of the solution to this irregular mixed problem is obtained.