Thermal Conductivity of SnTe between 100° and 500°K

Abstract

The thermal conductivity, electrical conductivity, and Seebeck coefficient of several specimens of SnTe have been measured between 100° and 500°K. The thermal conductivity is weakly dependent on both temperature and hole concentration. The total thermal conductivity is separated into an electronic and a lattice thermal conductivity. Because of the large concentrations of Sn vacancies in the samples, the phonons are scattered both by three-phonon umklapp processes and by the Sn vacancies; this results in a lattice thermal conductivity that varies with temperature more like T−½ rather than T−1. The Lorenz number relating the electrical conductivity and the electronic thermal conductivity is an unusual function of hole concentration. The Lorenz number is larger than the Sommerfeld value L0, varies with hole concentration p, and has a maximum value of about 1.3 L0 at p=2×1020 cm−3. This is consistent with the variation of the electrical conductivity and the Seebeck coefficient with hole concentration.