Thermoelectric transport properties of tetradymite-type Pb1-Sn Bi2Te4 compounds

We report thermoelectric transport properties of Pb 1- x Sn x Bi 2 Te 4 ( x = 0, 0.25, 0.5, 0.75 and 1) compounds. They exhibited n -type conduction behavior up to x = 0.5, while it changed to p -type due to the explosive hole generation at relatively high Sn contents. Their complicated charge transport behavior was interpreted by high-temperature Hall measurements and also by the first-principles calculation based on Boltzmann transport equation. Effects of the Sn content on the density of state (DOS) effective mass was investigated, and its relation to the observed Seebeck coefficients and power factors of the compounds has been explained.