Optimizing thermoelectric performance through Sb doping in Ge _0.8 Mn _0.1 Pb _0.1 Te alloys

Abstract GeTe‐based alloys are promising thermoelectric materials for use at medium temperatures owing to their excellent thermoelectric performance. In this study, Ge 0.8‐ x Mn 0.1 Pb 0.1 Sb x Te alloys were obtained via vacuum melting and hot‐press sintering. Sb doping effectively decreased the carrier concentration, resulting in an enhancement of the Seebeck coefficient and consequently imparting excellent electrical transport performance to the sample. With doping concentration increasing, the structure of the sample changed from rhombohedral to cubic, creating a more favorable band structure for electronic transport properties. The incorporation of Sb into GeTe intensifies the lattice defects within the material. The significant decrease in the lattice thermal conductivity of the Ge 0.71 Mn 0.1 Pb 0.1 Sb 0.09 Te alloy to 0.84 W m −1 K −1 at 323 K is primarily attributed to the phonon scattering effect emanating from the presence of edge dislocation, point defects, and inherent grain boundaries. Finally, the maximum ZT value of the Ge 0.74 Mn 0.1 Pb 0.1 Sb 0.06 Te alloy was ~ 1.53 773 K, which is a significant enhancement of 0.35 compared to the undoped Ge 0.8 Mn 0.1 Pb 0.1 Te alloy. This substantial improvement underscores the positive impact of the selected doping elements and their concentrations on the overall thermoelectric performance of the alloy.