Thermal Conductivities of (Bi_1-<i>x</i>Sb_<i>x</i>)₂Te₃and Bi₂(Te_1-<i>y</i>Se_<i>y</i>)₃Compounds

Abstract

Thermal conductivity of the semiconducting compounds (Bi1-xSbx)2Te3 and Bi2(Te1-ySey)3 is measured in the cleavage planes in the temperature range of 90∼300K. It is found that the heat conduction by charge carriers is smaller than that by phonons and the heat conduction due to the simultaneous thermal diffusion of electron and hole is as important as the lattice thermal conduction at temperatures near 300K. The anharmonicity and disorder parameter are obtained from the lattice thermal conductivity with the aid of the Klemens-Callaway theory. Consideration of the relations between the anharmonicity and the disorder parameter leads to the following conclusion: the three-phonon processes are modified by point defects, and the phonon-phonon interaction of the type a+a\rightleftarrows0 participates in the lattice thermal conduction, where a and 0 refer to the acoustic and optical phonon, respectively.