Low Temperature Transport in Solid Solutions of Bismuth-Antimony Tellurides with Arsenic, Copper, and Tin

In this work, we have investigated the temperature dependences of the resistance $$\rho$$ (in the temperature range $$4.2~\textrm{K}<T<330$$ K) of single crystals of Bi $${}_{2-x}$$ As $${}_{x}$$ Te $${}_{3}$$ ( $$0<x<0.034$$ ), Sb $${}_{2-x}$$ Cu $${}_{x}$$ Te $${}_{3}$$ ( $$0<x<0.1$$ ), and Sb $${}_{2-x}$$ Sn $${}_{x}$$ Te $${}_{3}$$ ( $$0<x<0.0075$$ ), as well as the thermopower and thermal conductivity of solid solutions of Bi $${}_{2-x}$$ As $${}_{x}$$ Te $${}_{3}$$ in the temperature range $$77~\textrm{K}<T<330$$ K. In the temperature range of 100–320 K, the dependence $$\rho(T)$$ follows a power law with an exponent $$m=2$$ (Bi $${}_{2-x}$$ As $${}_{x}$$ Te $${}_{3}$$ ), $$m=1.2{-}1.1$$ (Sb $${}_{2-x}$$ Cu $${}_{x}$$ Te $${}_{3}$$ ), and $$m=1.2{-}0.6$$ (Sb $${}_{2-x}$$ Sn $${}_{x}$$ Te $${}_{3}$$ ). For Bi $${}_{2-x}$$ As $${}_{x}$$ Te $${}_{3}$$ , it has been established that the conductivity decreases, while the Seebeck coefficient initially increases significantly and then decreases with increasing x. The thermal conductivity of samples with As decreases compared to the original bismuth telluride at $$T<250$$ K. As a result, the maximum thermoelectric figure of merit ZT shifts from 300 to 250 K with increasing As content.