Influence of mechanochemical syntheses and compacting methods on the thermoelectric properties of nanostructured AgSnmSbTe2+m (TAST-m)

Kurzfassung

Tin telluride doped with silver antimony telluride (Tin-Antimony-Silver-Tellurium, TAST-m) was prepared by two mechanochemical methods: mechanical alloying and—as an alternative synthetic route—co-ball-milling, a recently developed way of combining the procedures of mechanical alloying of single elements with the usual ball-milling of polycrystalline compounds. For the two series of products with varying degrees of doping, three different compacting techniques, cold-pressing/annealing (CPA), hot-pressing (HP) and short-term sintering (STS), were applied, and their influence on the thermoelectric properties was investigated. Although short-term sintering seemed to be the most advantageous method in most cases, the influence of the density of an individual pellet on the thermoelectric transport properties needs to be considered. A structural characterization of the different series of nanopowders obtained by the two milling methods was carried out by x-ray diffraction (XRD) and transmission electron microscopy (TEM) studies. The latter also allowed further insight into the microstructure and revealed a homogeneous distribution of silver and antimony in the tin telluride matrix.