Preparation and Thermoelectric Properties of Ga and K Dual Doped P-Type Bi0.5Sb1.5Te3

Abstract:

Ga and K dual doped Bi0.5Sb1.5Te3 thermoelectric materials were prepared by vacuum melting and hot pressing. XRD results indicate that all the characteristic peaks of the bulk Ga0.02Bi0.5Sb1.48-xKxTe3 can be indexed into Bi0.5Sb1.5Te3, but the diffraction peaks of the dual doped samples slightly lean to the left. Hot-pressed bulk materials exhibit the (00l) preferred orientation. SEM morphology shows that microstructure is dense and layered structure. The Seebeck coefficient of Bi0.5Sb1.5Te3 near the room temperature can be improved to some extent by Ga and K dual doping. The electrical conductivity of dual doped samples can be improved in different degrees, and electrical conductivity of Ga0.02Bi0.5Sb1.42K0.06Te3 samples is improved obviously. In the whole measured temperature range of 300~500 K, the thermal conductivity of the dual doped samples is higher than that of Bi0.5Sb1.5Te3. ZT values of the dual doped samples are improved at near 300 K, and the ZT value of Ga0.02Bi0.5Sb1.42K0.06Te3 sample reaches 1.5 at 300 K.

Key words:dual doping; vacuum melting; hot pressing; microstructure; thermoelectric properties