The effect of Ni/Sn doping on the thermoelectric properties of BiSbTe polycrystalline bulks

Abstract The diffusion of Ni and Sn is undesirable in thermoelectric (TE) device. However, the quantitative effect on TE properties is unknown. In this work, the effect of Ni/Sn doping on the TE properties of p-type Bi 2 Te 3 based alloys and the corresponding mechanism are investigated to provide beneficial reference for device designers and researchers. The results show that nickel doping in Bi 0.4 Sb 1.6 Te 3 can make the intrinsic excitation temperature shift to lower temperature region due to the formation of the second phase NiTe, which greatly reduces the carrier concentration and increases the electrical resistivity. Ultimately, the thermoelectric figure of merit ( ZT value) deteriorates rapidly with the increase of Ni content, and only 7 wt ‰ Ni results in a 32% drop in ZT value. Tin doping moves the intrinsic excitation temperature to higher temperature region due to the promotion of Sn’ Bi to the generation of anti-sites (Bi’ Te and Sb’ Te ), which significantly increases the carrier concentration and deteriorates the Seebeck coefficient. At last, the ZT value also declines sharply with the increase of Sn content, and just 7 wt ‰ Sn doping results in a 52% drop in ZT value.