Thermoelectric properties of nanocomposite Bi$_{0.45}$Sb$_{1.55}$Te$_{2.985}$ solid solution with SiO$_2$ microparticles

Nanocomposite thermoelectrics based on Bi$_{0.45}$Sb$_{1.55}$Te$_{2.985}$ solid solution of $p$-type conductivity are fabricated by the hot pressing of nanopowders of this solid solution with the addition of SiO$_2$ microparticles. Investigations of the thermoelectric properties show that the thermoelectric power of the nanocomposites increases in a wide temperature range of 80–420 K, while the thermal conductivity considerably decreases at 80–320 K, which, despite a decrease in the electrical conductivity, leads to an increase in the thermoelectric efficiency in the nanostructured material without the SiO$_2$ addition by almost 50% (at 300 K). When adding SiO$_2$, the efficiency decreases. The initial thermoelectric fabricated without nanostructuring, in which the maximal thermoelectric figure of merit $ZT$ = 1 at 390 K, is most efficient at temperatures above 350 K.