LOW TEMPERATURE THERMOELECTRIC PROPERTIES OF Bi-Sb ALLOYS WITH PARTIAL SUBSTITUTION OF Ag OR Zn FOR Sb

Bi-Sb-Ag and Bi-Sb-Zn alloys with the general formula of Bi85Sb15-xAgx(x = 0, 1, 3, 5, 7) and Bi85Sb15-xZnx(x = 1, 3, 5, 7), respectively, were prepared by mechanical alloying and subsequent pressure-less sintering. The phase structures of the samples were investigated by X-ray diffraction. Thermoelectric properties were investigated by measuring electrical conductivity, Seebeck coefficient and thermal conductivity in the temperature range of 80-300 K. The results show that the figure-of-merit of sample Bi85Sb14Ag1 reach a maximum value of 2.16x10-3 K-1 at 219 K, which is twice as large as that of the reference sample Bi85Sb15. The value of 1.58x10-3 K-1 for figure-of-merit was obtained in the sample Bi85Sb14Zn1 at 155 K, which is about 78 percent larger than that of the reference sample Bi85Sb15 at the same temperature. The maximum figure-of-merit value is obviously shifted towards lower temperature region