Origin of resistivity anomaly in p-type leads chalcogenide multiphase compounds

The electrical resistivity curves for binary phase compounds of p-type lead chalcogenide (PbTe)(0.9−x) (PbSe) 0.1 (PbS) x, (x = 0.15, 0.2, 0.25), which contain PbS-rich secondary phases, show different behaviour on heating and cooling between 500-700 K. This is contrast to single phase compounds which exhibit similar behaviour on heating and cooling. We correlate these anomalies in the electrical resistivities of multiphase compounds to the variation in phase composition at high temperatures. The inhomogeneous distribution of dopants between the matrix and secondary phase is found to be crucial in the electronic transport properties of the multiphase compounds. These results can lead to further advances in designing composite Pb-chalcogenides with high thermoelectric performance.