Effective mass and mobility in solid solutions p - Bi2-x SbxTe3-y Sey for temperatures < 300 K

The temperature dependences of the Seebeck coefficient α and of the electrical conductivity σ of p - Bi2-x SbxTe3-y Sey solid solutions were studied under atomic substitution on the cation (1 ≤ x ≤ 1.5) and anion (0.04 ≤ y ≤ 0.09) bismuth and antimony telluride sublattices within the temperature interval 80-340 K. The effect of variation in the solid-solution composition on the average effective density-of-states mass (m/m0) and carrier mobility (μ0, calculated with due account of degeneracy) was studied under the assumption that carrier scattering is isotropic and that the relaxation time can be approximated by a power-law function τ = aEreff, where reff is an effective scattering parameter. It is shown that variations in the pattern of the m/m0 and μ0 temperature dependences produced in the temperature range under study by properly varying the number of substituted atoms in the solid solutions may favor an increase in thermoelectric efficiency