Enhancement of Thermoelectric Figure of Merit by the Insertion of MgTe Nanostructures in <i>p</i>‐type PbTe Doped with Na₂Te

Abstract The thermoelectric properties of crystalline melt‐grown ingots of p ‐type PbTe– x MgTe ( x = 1–3 mol%) doped with Na 2 Te (1–2 mol%) were investigated over the temperature range of 300 K to 810 K. While the powder X‐ray diffraction patterns show that all samples crystallize in the NaCl‐type structure with no MgTe or other phases present, transmission electron microscopy reveals ubiquitous MgTe nanoprecipitates in the PbTe. The very small amounts of MgTe in PbTe have only a small effect on the electrical transport properties of the system, while they have a large effect on thermal transport significantly reducing the lattice thermal conductivity. A ZT of 1.6 at 780 K is achieved for the PbTe containing 2% MgTe doped with 2% Na 2 Te.