Effect of SiC on thermoelectric properties of P-type Bi_0.5Sb_1.5Te₃ alloy prepared by pulverizing and sintering method

SiC particles in the different volume fraction were mixed into Bi_0.5Sb_1.5Te₃+5%Te alloy powders (mass fraction) prepared by the pulverizing method. The mixed powders were sintered into the blocks by spark plasma sintering (SPS) method. The microstructure and thermoelectric properties of these block samples were investigated. The results show that, with the increase of SiC volume fraction, the orientation of the bulks is weakened, the microstructure is refined, the carrier concentration increases, and the mobility decreases. Due to the weakened orientation and the refined microstructure, the scattering of phonons is enhanced, leading to a reduced lattice thermal conductivity. However, due to the deterioration of the electrical properties for the blocks, the dimensionless thermoelectric value (ZT) of the bulks with SiC has no improvement. When the volume fraction of SiC is 0.40%, the block samples show the best thermoelectric performance with ZT = ~0.81 at 322 K.