Physical and chemical properties of low-temperature nanostructured thermoelectric materials on the basis of Bi2Te2.8Se0.2 and Bi0.5Sb1.5Te3

Abstract

Nanostructured thermoelectric (TE) materials Bi2Te2.8Se0.2 (0.16 wt.% CdCl2) n-type and Bi0.5Sb1.5Te3 (2.2 wt.% Te and 0.16 wt.% TeI4) p-type were fabricated, and complex investigations of these materials were carried out. The thermoelectric materials were obtained by spark plasma sintering (SPS) of nanodispersed powder ground in planetary ball mill. It was found that the average particle sizes in thermoelectric materials after milling for 60 min were about 30 nm. After SPS of the powders, the average crystallite sizes were from 86 to 96 nm. Thermal stability of materials up to 550 K was observed. The relationship between the composition, structure and properties of TE materials was established. The maximum ZT obtained for nanostructured TE materials were ZT=1.16 at 380 K for Bi2Te2.8Se0.2 and ZT=1.35 at 370 K for Bi0.5Sb1.5Te3. Increase in ZT for nanostructured thermoelectric materials is due to the decrease of the lattice thermal conductivity.