Effect of hydrostatic strain on the lattice thermal conductivity and thermoelectric properties of Bi2Te3

Abstract

The effect of hydrostatic strain on the lattice thermal conductivity and thermoelectric properties of bulk Bi2Te3 at room temperature (300 K) is investigated by ab initio calculations. The temperature-dependent effective potential method was employed to account for the strong anharmonicity of Bi2Te3. The results show that the lattice thermal conductivity of Bi2Te3 is strongly influenced by hydrostatic strain. Also, the softening of the low-frequency acoustic branch and the enhancement of anharmonicity due to tensile strain can significantly reduce the lattice thermal conductivity in the out-of-plane direction, resulting in a marked increase in ZT values in this direction. At a hydrostatic tensile strain of only 0.4%, the lattice thermal conductivity in the out-of-plane direction decreases by about 43%, while the ZT value increases by up to 39%.