Homologous series of layered tetradymite-like compounds in the Sb-Te and GeTe-Sb2Te3 systems

The structures of layered compounds in thenSb2 ·mSb2Te3 andnGeTe ·mSb2Te3 homologous series were studied by x-ray diffraction. GeSb6Te10 (n = 1,m = 3) was shown to have a 51-layer structure (sp. gr.\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$R\bar 3m$$ \end{document}) withc = 10.202(1) nm. In the structure of GeSb6Te10, Sb2Te3 five-layer slabs and GeSb2Te4 sevenlayer slabs are stacked along thec axis in the ordered sequence -557 557 557-. Crystallographic data for this compound are presented. The specific and common structural features of the layered compounds in thenSb2 ·mSb2Te3 andnGeTe ·mSb2Te3 homologous series are discussed.