Composition-Dependent Thermoelectric Properties of (PbTe)_100−x(Bi₂Te₃-Sb₂Te₃)_x (0.1≤x≤5)

Abstract

We report room-temperature thermoelectric properties of polycrystalline (PbTe)_100−x(Bi₂Te₃-Sb₂Te₃)_x (0.1≤x≤5). At x≤0.25, with a decrease of x, the electrical resistivity increases dramatically whereas the Seebeck coefficient and the thermal conductivity nearly keep constant. At x≥0.5, the electrical conductivity, the thermal conductivity and the Seebeck coefficient in absolute value slightly decrease with increasing x. It is found that, the thermal conductivity of the PbTe sample with Bi₂Te₃ and Sb₂Te₃ as the sources of dopants is much smaller than that of doping with other dopants at the same carrier concentration. With an increase of x, the figure of merit, Z, which is calculated from the measured quantities, increases at first and then decreases and shows a maximum value of 8.97×10⁻⁴ K⁻¹ at x=0.2. This value is several times higher than that of small grain-size PbTe containing other dopants.