An analysis of the thermoelectric efficiency of n-(Bi,Sb)(2)(Te,Se,S)(3) solid solutions within an isotropic scattering model

A study is reported on the thermoelectric properties of n-type solid solutions Bi2Te3 - ySey (y = 0.12, 0.3, 0.36), Bi2 - xSbxTe3 - ySey (x = 0.08, 0.12; y = 0.24, 0.36), and Bi2Te3 - zSz (z = 0.12, 0.21) as functions of carrier concentration within the 80- to 300-K range. It has been established that the highest thermoelectric efficiency Z is observed in the Bi2Te3 - ySey (y = 0.3) solid solution containing excess Te at optimum carrier concentrations (0.35 x 10(19) cm(-3)) and at temperatures from 80 to 250 K. The increase in Z in the Bi2Te3 - ySey solid solution compared with Bi2 - xSbxTe3 - ySey and Bi2Te3 - zSz is accounted for by the high mobility mu (0), an increase in the effective mass m/m(0) with decreasing temperature, the low lattice heat conductivity kappa (L), and the weak anisotropy of the constant-energy surface in a model assuming isotropic carrier scattering. (C) 2000 MAIK Nauka/Interperiodica.