Effect of spark plasma sintering temperature on thermoelectric properties of (Ti,Zr,Hf)NiSn half-Heusler compounds

The effect of spark plasma sintering (SPS) temperature on thermoelectric properties of (Ti,Zr,Hf)NiSn half-Heusler compounds were studied. Four kinds of samples were prepared: an arc-melted sample, a sample sintered at 973 K by SPS (SPS-973), a sample sintered at 1173 K by SPS (SPS-1173), and a sample sintered at 1373 K by SPS (SPS-1373). The power factor of SPS-1173 is several % lower than that of the arc-melted sample, but the thermal conductivity is reduced to 70% of that of the arc-melted sample. As a result, the dimensionless figure of merit ZT of SPS-1173 is improved and it reaches 0.43 at 760 K.