Thermoelectric performance of P-type Bi85Sb15-xSnx alloys prepared by mechanical alloying and pressureless sintering at low temperatures

Abstract

In the present study, the Bi85Sb15-xSnx (x=0, 1, 2, 3) thermoelectric materials have been fabricated through mechanical alloying followed by pressureless sintering. The phase composition and the microstructure were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. Electrical conductivity, Seebeck coefficient and thermal conductivity were measured in the temperature range of 77∼300K. The electrical conductivity was characterized by using four-probe method. The Seebeck coefficient was determined from measured temperature and electric potential difference between the two ends of the bar-shape specimen. The thermal conductivity was measured by means of a heat and sink steady state method. Then the power factor and ZT were calculated according to the measurement values. The results showed that the Sn-doped samples changed from n-type to p-type at low temperature. A maximum power factor of 1.67 ×10-3W/mK2 and a minimum thermal conductivity of 1.8W/mK were obtained. The optimum ZT value of 0.15 was obtained at 300K.