Thermoelectric properties of p-type Bi0.5Sb1.5Te3 for solid-state cooling devices

The p-type Bi0.5Sb1.5Te3 sintered at 450 or 500 °C with various powder sizes (<45, 45–105, 106–150 μm) was single phase with a rhombohedral structure (R3¯m). The electrical and thermal conductivities of the Bi0.5Sb1.5Te3 sintered at 500 °C were higher than those of the Bi0.5Sb1.5Te3 sintered at 450 °C mainly because of a higher hole concentration. The Bi0.5Sb1.5Te3 fabricated with intermediate powders (45–105 μm) in size had the highest hole concentration and the lowest porosity, resulting in the highest electrical conductivity. The Bi0.5Sb1.5Te3 sintered at 450 °C with the smallest powder (<45 μm) in size showed the highest value of the Seebeck coefficient (240 μV/K) mainly because of the lowest hole concentration (0.439 × 1025 m−3). We obtained the highest figure-of-merit (2.82 × 10−3/K) for the Bi0.5Sb1.5Te3 sintered at 450 °C with intermediate powders.