Synthesis and Thermoelectric Properties of Tin-Filled Skutterudite, SnxCo4Sb12

Tin atoms were inserted into the skutterudite-type CoSb3 host lattice under high pressure and temperature conditions. It was found that Sn atoms could be inserted into the body-centered vacant site, resulting in the formation of new filled (or partially filled) skutterudites, SnxCo4Sb12. The degree of insertion (x) increases with increasing applied pressure, and the vacant sites of the CoSb3 host lattice is fully occupied by Sn atoms when the reaction is carried out at 8GPa and at 550°C. X-ray Rietveld refinement revealed that the inserted Sn atom showed an anomalously large isotropic atomic displacement parameter, indicating a large thermal vibration amplitude at the body-centered position. The Sn-filled skutterudites exhibit n-type semiconducting behaviour indicating that Sn filling causes the formation of a donor level.