Synergistically improving the thermoelectric and mechanical performance for p-type MnGeSbTe alloys.

The MnGeTe compound crystallizes in a cubic structure without any phase transition and has great potential for enhancing the thermoelectric merit of MnGeTe-based materials. In this work, Sb was used as an effective dopant to replace Ge sites in MnGeTe compounds. By optimizing the carrier concentration, excellent power factors can be obtained in the tested temperature range. Meanwhile, the characterization results show that Sb doping introduces point defects and induces grain refinement, which enhances phonon scattering and improves thermoelectric transport performance by reducing lattice thermal conductivity. Eventually, the value increases from ∼0.65 for pure phase MnGeTe to ∼0.84 for MnGeSbTe at 717 K by synergistic regulation of the electrical and thermal conductivities. In addition, the hardness test results of the samples show that the doping of Sb endows the MnGeTe-based thermoelectric material with a higher Vickers hardness (>200 H) and shows favorable mechanical properties.