Thermoelectric Properties of Group 13 Elements-Triple Filled Skutterudites: Nominal In_xGa_0.02Tl_0.20Co₄Sb₁₂

Abstract

The high-temperature thermoelectric (TE) properties of group 13 elements (Ga, In, and Tl) triple-filled skutterudites in the nominal compositions of In_xGa_0.02Tl_0.20Co₄Sb₁₂ (0 ≤ x ≤ 0.30) were investigated. All samples contained impurity phases in addition to the skutterudite matrix phase, i.e. some of the filler elements added to CoSb₃ precipitated as the metal state and antimonides. With increase the starting amount of In, the actual content of In increases while that of Tl decreases. Owing to phonon scattering by rattling of the group 13 elements, low lattice thermal conductivity was achieved, leading to relatively high TE figure of merit (ZT) for all samples. The maximum ZT value was 0.72 at 773 K obtained for the sample in the nominal composition of In_0.30Ga_0.02Tl_0.20Co₄Sb₁₂.