Microwave activated hot pressing: A new opportunity to improve the thermoelectric properties of ntype Bi2Te3 xSex bulks

Abstract In this article, n⿿type Bi 2 Te 3  ⿿ x Se x ( x  = 0.15, 0.3, 0.45, 0.6) compounds were prepared successfully via a new consolidation technique named Microwave Activated Hot Pressing (MAHP) to explore the optimum composition with the best thermoelectric properties. The results showed that the relatively low sintering temperature and short holding time used in this work could suppress grain growth. The sintered samples showed a typical multi⿿scale microstructure, consisting of fine lamellar grains and irregular granular grains. Moreover, the doped selenium promoted grain refinement. With the variation of selenium content, a highest power factor of 1.75 y 10 ⿿3  Wm ⿿1  K ⿿2 was achieved for Bi 2 Te 2.7 Se 0.3 sample around 423 K. And a minimum thermal conductivity of 0.85 Wm ⿿1  K ⿿1 was achieved around 423 K for Bi 2 Te 2.4 Se 0.6 sample. Considering the comprehensive thermoelectric properties, a highest ZT value of 0.73 was obtained for Bi 2 Te 2.55 Se 0.45 sample around 423 K.