Thermoelectric performance of Te composited with FeTe₂ and co-doped with Sb and Se

In recent years, the element semiconductor Te has been considered as a potential thermoelectric material in the middle temperature region due to its excellent thermoelectric performance and high stability. However, it is necessary to dop with high toxic As element or low toxic Bi or Sb under high pressure conditions to obtain a moderate carrier concentration. In this study, we synthesized Sb-Se doped and FeTe₂ composited Te under lower pressure conditions. The results show that the solid solubility of Fe in Te does not exceed 5 at%. After exceeding its solid solubility, Fe is precipitated in the form of FeTe₂. The electrical transport properties and thermal conductivity of Te were tuned effectively by FeTe₂ composite and Sb doping. The maximum ZT value of the sample with the composition of Fe_0.1Te_0.9Sb_0.003 reaches 0.65 at 607 K, which is much higher than that of the pristine Te. The thermal conductivity was further reduced by Se doping. Thereby, the ZT value of the sample Fe_0.1Te_0.872Sb_0.003Se_0.025 was enhanced to 0.76 at 580 K. These results show that combining with doping and composite can improve the thermoelectric properties of Te effectively.