Enhanced Thermoelectric Properties of (PbTe)0.88(PbS)0.12 Composites by Sb Doping

The effects of Sb doping on (PbTe)(0.88)(PbS)(0.12) composites prepared by melting, ball milling, and spark plasma sintering were investigated. The x-ray diffraction results indicate that all samples Sb (x) Pb1-x Te0.88S0.12 with x = 0, 0.002, 0.004, 0.006 and 0.008 are composites containing PbTe with NaCl-type structure as the major phase and PbS with NaCl-type structure as the minor phase. The electrical resistivity is reduced with increasing Sb doping, from 1.95 x 10(-5) Omega m for Sb content x = 0 to 5.55 x 10(-6) Omega m for x = 0.008 at 298 K, showing that Sb is an efficient electron donor. However, the absolute Seebeck coefficient decreases, from 196 mu V/K for x = 0 to 57.0 mu V/K for x = 0.008 at 298 K, and the thermal conductivity increases, from 0.989 W/m K for x = 0 to 1.64 W/m K for x = 0.008, with Sb doping. The power factor and figure of merit ZT can be enhanced by proper Sb doping. The maximum dimensionless figure of merit ZT of 1.20 was obtained in the sample Sb0.004Pb0.996Te0.88S0.12 at 773 K.