Influence of rare earth doping on thermoelectric properties of SrTiO_3 ceramics

摘要

Thermoelectric properties of SrTiO_3 ceramics, doped with different rare earth elements, were investigated in this work. It's found that the ionic radius of doping elements plays an important role on thermoelectric properties: SrTiO_3 ceramics doped with large rare earth ions (such as La, Nd, and Sm) exhibit large power factors, and those doped with small ions (such as Gd, Dy, Er, and Y) exhibit low thermal conductivities. Therefore, a simple approach for enhancing the thermoelectric performance of SrTiO_3 ceramics is proposed: mainly doped with large ions to obtain a large power factor and, simultaneously, slightly co-doped with small ions to obtain a low thermal conductivity. Based on this rule, Sr_(0.8)La_(0.18)Yb_(0.02)TiO_3 ceramics were prepared, whose ZT value at 1023K reaches 0.31, increasing by a factor of 19% compared with the single-doped counterpart Sr_(0.8)La_(0.18)Yb_(0.02)TiO_3(ZT = 0.26).