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In this paper, n-type lead telluride (PbTe) compounds without doping were sucessfully prepared at high pressure and high temperature (HPHT). The carrier type was induced by the effect of pressure. The results of the electrical conductivity, Seebeck coefficient, thermal conductivity for n-type PbTe, which were measured at room temperature, show that the PbTe samples prepared by HPHT exhibit the same characteristics as heavily doped semiconductors. The figure-of-merit, Z, of 5:46 Â 10 À4 K À1 was obtained, which is higher than the heavily doped samples of PbTe at room temperature. These results indicate that this method has potential application in obtaining good quality thermoelectric materials with improved properties.

We report the enhanced thermoelectric properties of PbTe alloyed with antimony telluride (Sb2Te3). The resistivities and absolute values of the Seebeck coefficient for PbTe alloyed with Sb2Te3 increase while the thermal conductivities decrease with rising temperature. A maximum figure of merit, ZT, of 1.17 has been achieved for PbTe alloyed with 0.8 mol% Sb2Te3 at 560 K. This value is about 30% higher than the ones reported previously for bulk PbTe. The enhanced thermoelectric properties may be due to the low thermal conductivities which are induced by alloying with Sb2Te3 and much smaller than that reported for bulk PbTe.