Crystal structure, electronic structure, and thermoelectric properties of AuTlSb: A new pyrite superstructure

The ternary compound AuTlSb adopts a new structure type in the orthorhombic space group Pna21 with lattice constants a = 6.5507(8) Å, b = 14.2871(18) Å, c = 6.5254(9) Å. The structure contains Au atoms octahedrally coordinated to SbSb and TlTl dimers, and can be viewed as an ordered superstructure of AuSb2 (pyrite). In addition to the synthesis and crystal structure of AuTlSb, we report extended Hückel band structure calculations and bonding analysis, as well as electrical resistivity and thermopower measurements between 80 K and 300 K. For comparison, we include the results from extended Hückel calculations on the parent structure AuSb2. The band structure calculations predict AuTlSb to be metallic, which is in agreement with the transport properties measurements.