Synthesis and Properties of Type-I Clathrate Phases Rb8-x-tKx...tAuyGe46-y.

Type-I clathrates Rb8-x-tKx...tAuyGe46-y are synthesized from Rb4G9, K4Ge9 Au, and Ge. Crystal structures and compositions are determined by single-crystal and powder X-ray diffraction methods. The lattice parameters are 10.8103(2), 10.7956(2), 10.7850(2), and 10.7723(2) A in space group Pm3n for Rb7.88(2) Rb3.69(4)K4.31(4)Au2.l7(2)Ge43.83(2) Rb1.66(S)K6.34(S)Au2.17(I)Ge43.831 )» ana K671(4Au2.28(2)Ge43.72(2)1 respectively. Bonding analysis for Rb8A6Ge40 suggests ionic interaction of Rb with the framework besides covalent interactions between Ge and Au/ Ge. Rb7 88Au2.47Ge43 S3 and K7,(4yAu12gGe4372 are both diamagnetic. The heat capacity of K6.71Au2.28KGe43.53 is analyzed. Transport properties of Rb7.88Au2.47Ge43.72(2)reveal n-type conducting, and low thermal conductivity. [ABSTRACT FROM AUTHOR]