High-temperature thermal transport in heavily doped small-grain-size lead telluride

Abstract

An improved theoretical model has been used to analyse the high-temperature thermal conductivity of dopedn-type lead telluride in terms of the separate contributions from electrons and phonons. At high carrier concentrations the electronic thermal conductivity is significant and the non-parabolic nature of the energy bands must be included to obtain a reasonable agreement with experimental thermal conductivity data. Although acoustic phonon scattering is the dominant carrier scattering mechanism, the inclusion of polar optical mode scattering further improves the agreement between the theoretical results and experimental data. The improved model is employed to estimate the effect of grain-boundary scattering in reducing the thermal conductivity of small-grain-size material. At optimum doping the thermal conductivity of 1 μm grain size unalloyed lead telluride would be reduced by approximately 5% compared with the single-crystal data.