Influence of Ga-doping on the thermoelectric properties of Bi(2−x)GaxTe2.7Se0.3 alloy

Bi(2−x)GaxTe2.7Se0.3 (x=0, 0.04, 0.08, 0.12) alloys were fabricated by vacuum melting and hot pressing technique. The structure of the samples was evaluated by means of X-ray diffraction. The peak shift toward higher angle can be observed by Ga-doping. The effects of Ga substitution for Bi on the electrical and thermal transport properties were investigated in the temperature range of 300–500 K. The power factor values of the Ga-doped samples are obviously improved in the temperature range of 300–440 K. Among all the samples, the Bi(2−x)GaxTe2.7Se0.3 (x=0.04) sample showed the lowest thermal conductivity near room temperature and the maximum ZT value reached 0.82 at 400 K.