Thermoelectric properties of Bi 0.5 Sb 1.4− x Na x In 0.1 Te 3 alloys

Abstract The Bi 0.5 Sb 1.4− x Na x In 0.1 Te 3 ( x = 0.02–0.20) alloys were fabricated by high vacuum melting and hot‐pressing technique. The phase structures and morphology of the bulk samples were characterized by X‐ray diffraction (XRD) and scanning electron microscope (SEM), respectively. Effects of In and Na co‐doping on the electrical and thermal transport properties were studied from room temperature to 500 K. Seebeck coefficient of the Bi 0.5 Sb 1.5 Te 3 can be enhanced by substituting Sb with In and Na at near room temperature. The electrical conductivity of the In and Na co‐doped samples is lower than that of the Bi 0.5 Sb 1.5 Te 3 alloy from room temperature to 500 K. In and Na co‐doping of appropriate percentage optimizes the thermal conductivity of the Bi 0.5 Sb 1.5 Te 3 alloy. The minimum value of thermal conductivity of Bi 0.5 Sb 1.36 Na 0.04 In 0.1 Te 3 alloy is 0.45 W·m −1 ·K −1 at 323 K, which leads to a great improvement in the thermoelectric figure of merit ( zT ). The maximum zT value reaches 1.42 at 323 K.