Сполуки типу Tl6BC4 і A2TeC6 (А ‒ лужні метали і талій (І); В ‒ S, Se, Te; C ‒ F, Cl, Br, I): закономірності зміни та прогноз властивостей

Abstract

The aim of this study was to summarize the experimental information about certain physical properties of chalcohalide ternary compounds such as Tl6BC4 and A2TeC6 (where A = alkali metals and Tl (I); B = S, Se, Te; and C = F, Cl, Br, I) independing on the average charge of the nuclei of the chemical elements from which these compounds are built, as well as the creation of reasonable prognostic models based on the found patterns in order to predict the corresponding properties of hypothetical analogues. According to the results of the established regularities and corresponding generalizations, the predicted melting temperature has been estimated for the first time for the hypothetical ternary compounds of the compositions Tl6S(Se,Te)F4, T16S(Se,Te)Cl4, and Tl2TeF6(Cl6), and the band gaps have been obtained for the Tl6SF4(Cl4) and Tl2TeF6(Cl6) compounds. Analysis of the regularities found for the experimentally determined crystal structures of the ternary compounds A2TeC6(where A = alkali metals and Tl (I); C = halogen) crystallizing in the structural family of perovskite and its derivatives, could suggest that the compounds Li2(Na2)TeBr6 crystallize in one of the low-symmetric syngonies (monoclinic or triclinic), which are stable for this class of compounds with a significant difference inthe ionic radii of halogen and monovalent metal.