New Ternary Compounds MxTa11−xGe8 (M=Ti, Zr, Hf): Structure and Stabilization

Abstract

The title compounds M x Ta 11− x Ge 8 ( M =Ti, Zr, Hf) were prepared from the pure elements by arc-melting and subsequent induction heating at temperatures between 1200°C and 1400°C. X-ray powder diffraction studies of the samples were performed using the Guinier technique and the respective powder patterns were refined with a structure model based on the orthorhombic Cr 11 Ge 8 -structure type ( oP 76, Pnma ). The homogeneity ranges of the compounds were determined to be 0.9< x <1.3 ( M =Ti), 0.7< x <1.3 ( M =Zr) and 0.7< x <2.4> ( M =Hf) by means of electron probe microanalysis. Chemical bonding, electronic structure and site preferences are discussed based on extended Hückel calculations performed on hypothetical binary Ta 11 Ge 8 .