Microstructure and Thermoelectric Properties of P-type Bi_(0.5)Sb_(1.5)Te_3 Compounds Prepared by Spark Plasma Sintering

摘要

The microstructure and thermoelectrical properties of the 4wt% Te doped p-type Bi_(0.5)Sb_(1.5)Te_3 compounds, fabricated by using spark plasma sintering in the temperature ranging from 250°C to 350°C, were characterized. The density of the sintered compounds was increased to 99.2% of theoretical density by carrying out the consolidation at 350°C for 2 min. The Seebeck coefficient, thermal conductivity and electrical resistivity were dependent on hydrogen reduction process and sintering temperature. The Seebeck coefficient increased with reduction process while the electrical resisitivity significantly decreased. Also, the electrical resistivity decreased and thermal conductivity increased with sintering temperature. The results suggest that the carrier density and mobility vary with reduction process and sintering temperature. The highest figure of merit of 3.5x10~(-3)/K was obtained for the compounds spark plasma sintered at 350°C for 2 min by using the hydrogen-reduced powders.