Estimation of the band gap of a series of new thermoelectric materials

Abstract

The band gap E_g of a number of new thermoelectric materials, such as skutterudites, clathrates, Heusler phases, (Ge,Sn,Pb)(Te,Se)]_m[(Bi,Sb)₂(Te,Se)₃]_n (m, n = 0, 1, 2…) ternary alloys, and others is estimated. Estimations are performed using Goldsmid-Sharp’s formula E_g = 2e|α_max|T_max, Vegard’s rule E_g = (mE_g^A + nE_g^B)/(m + n), and the empirical dependence T_max = f(E_g) (A and B denote the corresponding binary alloys, T_max is the temperature corresponding to the thermoelectric-power maximum |α_max| or the thermoelectric figure of merit (ZT)_max, and e is the elementary charge). It is shown that the empirical dependence E_g = f(T_max) gives the most accurate estimates of E_g for difference classes of thermoelectric materials.