Cold-press sintering and particle-size engineering of Bi_0.3Sb_1.7Te₃ for enhanced thermoelectric performance

Microstructural engineering is a crucial approach to improving the conversion efficiency of thermoelectric materials and enabling their broad application. In this study, Bi_0.3Sb_1.7Te₃ samples were fabricated via cold pressing, hot pressing, and combined cold/hot pressing, each followed by vacuum sintering, allowing for a systematic comparison of the effect of processing on thermoelectric properties. The cold-press sintered sample exhibited excellent Seebeck coefficient and electrical conductivity. Furthermore, combining particle size control through ball milling and centrifugation with the cold-press sintering process significantly enhanced the TE performance. The sample with an average particle size of ∼200 nm achieved a high ZT of 1.18 at 300 K, attributed to the enhancement of the Seebeck coefficient by filtering of low energy charge carriers and the reduction of thermal conductivity through interface scattering. These findings highlight the pivotal role of microstructural engineering through powder processing in optimizing the near-room-temperature performance of Bi_0.3Sb_1.7Te₃, providing guidance for further enhancement of p-type Bi-Sb-Te thermoelectrics.