High pressure synthesis and thermoelectric properties of CoSb ₃-based filled skutterudites CoSb₃

Filled skutterudites exhibit thermoelectric properties that comply with the concept of a "phonon-glass and electroncrystal (PGEC)". The optimal filled skutterudite for PGEC would have filler atoms that exhibit large thermal vibration amplitudes in the voids of the host skutterudite lattice. It is desirable that these loosely bound filler atoms give rise to strong phonon scattering without affecting the essential part of the band structure. In this report, the use of highpressure technique for the synthesis of CoSb ₃-based filled skutterudites is reviewed. By using the high-pressure technique, new filled skutterudites, M_xCo₄Sb₁₂ (M = Ge, Sn, and Pb), have been successfully synthesized without charge compensation of the host lattice. The structural aspect and the thermoelectric properties of M_xCo₄Sb₁₂ are discussed.