The clathrate Ba 8Cu xGe 46−x−y□ y: Phase equilibria and crystal structure

Abstract

Phase relations at 700 °C, 800 °C and solidus temperatures have been derived for the clathrate system Ba 8Cu x Ge 46− x − y □ y via X-ray single crystal and powder diffractometry combined with electron probe micro analysis and differential thermal analysis. The ternary clathrate phase derives from binary Ba 8Ge 43□ 3 and extends up to x=6. Structure investigations define cubic primitive symmetry with the space group type Pm 3 ¯ n consistent with a clathrate type I structure throughout the entire homogeneity region 0< x⩽6 but defect-free Ba 8Cu x Ge 46− x exists for x⩾5.5.