Increase in the thermoelectric power produced by mechanically alloyed Pb1−x Snx Te due to the presence of 15 nm SnO2 inclusions

Abstract

Evidence is presented that 15 nm diameter SnO2 inclusions comprising approximately 2 vol. % of bulk mechanically alloyed n-type Pb1−x SnxTe (when x = 7% and 27%) significantly increase the electrical power produced by the material when it is doped above 1019 cm−3 range. The experimentally measured temperature dependence of the electrical conductivity and Seebeck coefficient of Pb0.93 Sn0.07 Te doped to 1.2 × 1019 cm−3 and Pb0.73 Sn0.27 Te doped to 3.8 × 1018 cm−3 are shown to be consistent with those calculated in the framework of the Boltzmann transport equations using the relaxation time approximation and a three-band model for which the materials-specific constants are taken from published literature. The SnO2 inclusions are shown to impact the transport coefficients by changing the energy dependence and magnitude of the relaxation time due to the charge carrier scattering by a collection of inclusions in a geometry consistent with analysis of the x-ray diffraction data. Analysis of the experimental data shows that Pb0.93 Sn0.07 Te doped to 1.2 × 1019 cm−3 generates more power than would a material without the 2 vol. % of 15 nm SnO2 inclusions. Calculations using the experimentally validated model show that for carrier concentrations greater than 1 × 1019 cm−3, the presence of these inclusions increases the power factor of both alloys in the 300–700 K temperature range.