Bi0.5Sb1.5Te3belongs to Bi2Te3 based semiconductor thermoelectric material, it has a goodthermoelectric properties in the vicinity of room temperature. In the fields ofaerospace, military, automotive exhaust processors and so on, Bi0.5Sb1.5Te3thermoelectric material will be widely used. But the ZT of Bi0.5Sb1.5Te3 onlyabout 1, in order to enable Bi0.5Sb1.5Te3 thermoelectric material to be morewidely used, it is necessory to increase its ZT value. In this paper, two elements K and Ga are used to dope P-type Bi0.5Sb1.5Te3, by controlling the doping concentration of Ga to keep it in x = 0.02, changing the concentra实tion of K (x = 0.02,0.04,0.06), then Ga0.02 Bi0.5Sb1.48-xKxTe3 bulk material is prepared by vacuum melting and hot pressed sintering and the impact of the doping elements on Seebeck, electrical conductivity, thermal conductivity is studied. The experimental results show that in low or high-temperature region, doping K and Ga can increase Seebeck coefficient. Especially in the high temperature zone, the Seebeck ocoefficient off Ga0.02Bi0.5Sb1.42K0.06Te3 is significantly larger than that of Bi0.5Sb1.5Te3. In the experiment the doping concentration of Ga is 0.02, and the doping concentration of K is from 0.02 to 0.04, and 0.06, with K concentration increased the electrical conductivity of Ga0.02 Bi0.5Sb1.48-xKxTe3 increases continuously, especially fast in low temperatures zone. It is shown that K and Ga sh co- doped Bi0.5Sb1.5Te3 has greatly improved electrical conductivity. The thermal conductivity of Ga0.02 Bi0.5Sb1.48-xKxTe3 bulk material not only increases with the K concentration increasing, but also increases with temperature increasing. At 300Ke, the ZT value of Ga0.02Bi0.5Sb1.42K0.06Te3 achieves maximum, its value is 1.5. It shows co-doping of K and Ga can effectively improve the ZT value of Bi0.5Sb1.5Te3.
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