Thermoelectric Properties of Trisubstituted Skutterudite Co4Sb11Ge1−x−y Te x Se y Compounds

Abstract

Trisubstituted skutterudite compounds Co4Sb11Ge1−x−y Te x Se y (x = 0.70 to 0.85, y = 0; x = 0.60 to 0.75, y = 0.1) have been fabricated by the solid-state reaction method combined with a subsequent spark plasma sintering process, and their thermoelectric properties measured in the temperature range from 300 K to 800 K. As the Te fraction increases, the electrical and thermal conductivity of the samples increase gradually, while the absolute Seebeck coefficient falls. The electrical and thermal conductivity of the samples doped with Se (y = 0.1) decrease significantly compared with the Se-free samples (y = 0). Particularly, the lattice thermal conductivity of the y = 0.1 samples drop by 20% to 31% compared with that of the y = 0 samples with the same Ge fraction at 300 K. In comparison with the double-substituted compounds Co4Sb11Ge1−x Te x (x = 0.70 to 0.85), the trisubstituted compounds Co4Sb11- Ge0.9−x Te x Se0.1 (x = 0.60 to 0.75) exhibit better thermoelectric performance. A maximum dimensionless figure of merit of 0.99 is obtained at 775 K for Co4Sb11Ge0.2Te0.70Se0.1, which is about 16% higher than that of Co4Sb11- Ge0.2Te0.80 at the same temperature.