Thermoelectric properties of p-type (Bi2Te3) x(Sb2Te3)1-x single crystals doped with 3 wt. % Te

Abstract

In the present work, thermoelectric properties of p-type (Bi 2Te3)x (Sb2Te3) 1-x single crystals doped with 3 wt. % Te are theoretically explored for various chemical compositions (x = 0.18, 0.19, 0.20, 0.22, 0.24, 0.26) in the temperature range of 290-500 K. The influence of the chemical composition in enhancing the thermoelectric figure of merit (ZT) is discussed in detail. Using the nearly-free electron approximation and the Fermi-Dirac statistics, the temperature dependences of Fermi level (E f), Seebeck coefficient (S), and electrical conductivity (σ) are successfully reproduced as reported in the experimental study of Li [Intermetallics 19, 2002 (2011)]. The thermal conductivity contributions from phonons (κph), acceptor holes (κh), and electron-hole pairs (κbp) are included by employing Srivastava's scheme, Wiedemann-Franz law, and Price's theory, respectively. By combining all three contributions of the thermal conductivity we successfully explain the experimental measurements of the total thermal conductivity as reported by Li Furthermore, it is theoretically found that among all the compositions the p-type 20%(Bi2Te3)-80%(Sb 2Te3) sample has the maximum ZT value of 1.31 at 390 K, which is also in good agreement with the experimental results obtained by Li © 2013 American Institute of Physics.