The effect of chromium impurity on the thermoelectric properties of PbTe in the temperature range 100–600 K

In this work we have investigated the effect of the chromium (Cr) impurity on the thermoelectric properties of lead telluride (PbTe) bulk crystal with different Cr-content. The structural characterization of the crystals was done by x-ray diffraction and high-resolution transmission electron microscopic analyses. The incorporation of Cr in PbTe over the soluble limit has been found to replace Pb from the lattice site, forcing it to be precipitated into nanodots, with their dimensions in the range of 2–13 nm and their numbers increasing with the increase in Cr doping. The transport properties of the samples with different Cr-content have been evaluated through temperature dependent electrical resistivity, the Hall coefficient, and thermopower measurements in the temperature range of 100–600 K. The highest mobility is obtained as 1404 cm2/V s for a sample with a carrier concentration of 3.84 × 1018 cm−3 at 300 K. The high electron mobility and moderately higher value of the thermopower are expected to produce a high power factor of the samples with the highest value of 38.49 × 10−4 Wm−1K−2 in a specimen with a Cr-content of 1.45 at. % at room temperature. The power factor of the specimen with 1.3 at. % Cr-content is found to be above 29 × 10−4 Wm−1K−2 in the wide temperature range of 300–600 K.