Phase equilibria in the GeTe-Sb2Te3-Bi2Te3 quasi-ternary system

Phase equilibria in the GeTe-Sb2Te3-Bi2Te3 system were studied by differential thermal analysis, X-ray powder diffraction, and metallography and also by microhardness and density measurements in the polythermal sections GeSb2Te4-GeBi2Te4, GeTe-GeSbBiTe4, GeSb4Te7-GeSbBiTe4, GeSbBiTe4-Sb2Te3, GeSbBiTe4-Bi2Te3, and Ge2Sb2Te5-GeSbBiTe4, which are quasi-binary and partially quasi-binary sections. A quaternary compound of the composition GeSbBiTe4 was synthesized for the first time, which crystallizes in the trigonal system (space group \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$R\bar 3m - D_{3d}^5$$\end{document}) with the unit cell parameters a = 6.27 Å and c = 38.40 Å (melting point 850 K).