Effect of Composition on the Electrical Properties and Thermal Conductivity of Pb_1−xSn_xTe

Abstract

P-type Pb_1−xSn_xTe single crystals were prepared by a Bridgman method with various Sn content (x). Electrical conductivity (σ), Hall coefficient (R_H) and thermal conductivity (κ) were measured in the temperature range of 300 to 700 K. Hole concentration at 77 K changed from 2.0×10²⁴ to 4.9×10²⁶ m⁻³ as x varied from 0 to 1.0. The σ value increased monotonously with increasing x. The minimum of κ found at x=0.25 were resulted from that of the lattice thermal conductivity (κ_lattice), since the phonon-phonon scattering in the solid solution may have decreased the lattice thermal conductivity. The ratio of electrical conductivity to thermal conductivity (σ⁄κ), to which the figure of merit Z is proportional, increased with increasing x and then reached its maximum at x=0.5. It was revealed that the thermoelectric performance of Pb_1−xSn_xTe can be improved by controlling its composition.