Inhomogeneity in thermoelectrics caused by Peltier effect-induced temperature gradient during spark plasma sintering

This study investigated the reasons for inhomogeneity in the axial direction during spark plasma sintering (SPS) of a thermoelectric material. Bismuth antimony telluride, a p-type thermoelectric material, was sintered using high current (>200 A). X-ray diffraction and power factor analyses confirmed that the preferred orientation improved with increasing sintering temperature, and the power factor increased linearly with temperature. The temperature gradient from 700 to 725 K at 723 K sintering process, estimated from this unique correlation between sintering temperature and power factor, was five-fold that of the reported values. This extraordinary temperature gradient was presumably generated by the Peltier effect.