Effects of high-pressure high-temperature treatment on the thermoelectric properties of PbTe

Changes in the thermoelectric properties of nominally undoped stoichiometric PbTe caused by high-pressure high-temperature (HPHT) treatment near 6.5 GPa and 900 °C are reported. Comparison of the electrical resistivity, thermopower, and thermal conductivity suggest that the carrier concentration and lattice defect density are decreased by HPHT treatment. Annealing the treated samples at intermediate temperatures (500–600 °C) reversed the changes. These observations are consistent with Pb vacancies being “squeezed out” by the applied pressure, and subsequently reintroduced by annealing.