Electronic structure of Si and Ge gold-doped clathrates

The electronic properties of single phase type-I clathrate compounds, Ba8Au6(SiorGe)40 and Ba8Ge46-x have been investigated. The crystal structure, electrical resistivities, magnetic susceptibilities, the density of states at the Fermi level, and the band gap (where applicable) were determined. Ba8Au6Si40 and Ba8Au6Ge40 show a metallic behavior whereas Ba8Ge46-x is semiconducting. On a basis of this work, a first evidence is presented of the existence of type-I mixed-clathrates containing both silicon and germanium