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[en] Considered are the properties of the master phase of the high-meeting metal chalcogenides. Discussed is the nature of the chemical bond in sulfides, selenides and tellurides. The chalcogenides synthesis methods have been analyzed and the possible synthesis means are shown. The likely spheres where the rare-earth metal chalcogenides might be used, are described. Also highlighted are the most stable phases of transition metals, that are of the great practical value and are used as solid antifriction lubricants

[en] The data on the application, preparation and properties of presently known europium compounds with sulfur, selenium, tellurium, are systematized. Crystallographical, thermodynamic, thermophysical, electrical, magnetic and chemical properties of europium chalcogenides are considered

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[en] For the first time a study was made on the spectral dependence of reflection coefficient of La₂Te₃O₉ tablets annealed at 150, 400, 550 and 660 deg C. It was established that the presence of residual ray band near 700 cm^-1 and additional less intensive maximum R near 400 cm^-1 is typical for all La₂Te₃O₉ samlpes. The nature of the R maximum is conditioned by light interaction with oscillations of TeO₃^2- and La³⁺ ions respectively. Splitting of the basic reflection band and occurrence of additional extremums as compared to reflection band for α-modification and X-ray amorphous samples is typical for La₂Te₃O₉ samples with more complex crystal structure (β-modification). Frequencies of the main optical phonons, rates of their damping, oscillator strengths static and high-frequency dielectric permeabilities were determined

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[en] A possible mechanism of interaction of thermodynamically stable sesquioxides of rare-earth elements of the yttrium subgroup with hydrogen selenide at elevated temperatures of the order of 1100 - 1500 deg C is discussed on the basis of some theoretical premises. A two-stage mechnism of chemical reactions of selenation of the initial REE oxides with the formation of oxyselenide, an intermediate, is suggested. The key diagrams (of a hypothetical nature) of a possible course of chemical interaction of the oxides and oxyselenides of REE with hydrogen selenide are presented