The clathrate Ba8CuxGe46-x-y□y: Phase equilibria and crystal structure

Phase relations at 700 degrees C, 800 degrees C and solidus temperatures have been derived for the clathrate system Ba8CuxGe46-x-y square(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 Ba8Ge43 square(3) and extends up to x = 6. Structure investigations define cubic primitive symmetry with the space group type Pm (3) over barn consistent with a clathrate type I Structure throughout the entire homogeneity region 0 < x <= 6 but defect-free Ba8CuxGe46-x exists for x >= 5.5. (C) 2009 Elsevier Inc. All rights reserved.