Enhancement in thermoelectric performance of n-type Pb-deficit Pb-Sb-Te alloys

PbTe based materials are well known for their high performance thermoelectric properties. Here, a systematic study of thermoelectric transport properties of n-type Pb-deficit Pb0.98-xSbxTe alloys with carrier concentrations in the range of ∼10−19 cm−3 is presented from room temperature to 623 K. A maximum thermoelectric figure of merit (zT) of ∼0.81 was achieved at 623 K for 4 mol% Sb containing Pb-deficit composition, by the cumulative integration of enhanced power factor and significant reduction in thermal conductivity. The scattering of phonons at Pb vacancies, contributed to the reduction of lattice thermal conductivity, and thereby strikingly boosted the zT of the Pb-deficit samples when compared with the pristine Pb1-xSbxTe. [Display omitted] •Pb-deficit Pb0.98-xSbxTe alloys were prepared by vacuum seated-tube melting route.•Phonon scattering at the vacancies notably reduced the lattice thermal conductivity.•Significant boost in zT of Pb-deficit samples comparing stoichiometric Pb-Sb-Te.•Maximum zT ∼0.81 at 623 K was achieved for the composition Pb0.94Sb0.04Te.