Thermoelectric properties of silicon hexaboride prepared by spark plasma sintering method

Silicon hexaboride is attractive for various industrial applications because of its high temperature capability, high hardness and excellent electrical conductivity, in particular it is a promising material for use as a thermoelectric semiconductor at high temperature. We have used a spark plasma sintering technique to produce silicon hexaboride ceramics. The Seebeck coefficient, electrical conductivity and thermal conductivity were measured and the effect of additives, phase composition and microstructure on the thermoelectric properties were discussed. The approximate value of Z (figure of merit value) of the SPS specimen reached about 9.6x10(-6)/K at 1273 K. The thermoelectric properties (Z) of the SPS specimen are improved in comparison with the specimen by hot-pressing. The effect of the addition of lanthanum and boron on thermoelectric properties of SiB6 were also evaluated.