Recrystallization and orientation competition via hot extrusion in n-type Bi₂Te₃ alloys for advanced power generator

The dual shortcoming of low thermoelectric and poor mechanical properties of zone-melting n-type Bi₂Te₃-based materials constitute a bottleneck that restricts their large-scale industrial applications in complex fields. In the present study, hot extrusion (HE) technique combined with Cu doping is used to achieve the co-optimization of the thermoelectric and mechanical properties of n-type Bi₂Te₃-based materials. The hot extrusion temperature (recrystallization temperature) is a crucial parameter to control the texturing and grain size, which can effectively regulate the internal defect structure of the material. Combined with the effect of Cu doping, the thermoelectric merit ZT of the samples at the extrusion temperature of 793 K reaches 1.14 at 375 K, and the average ZT value reaches 1.07 in the temperature range of 300–460 K. Simultaneously, the flexural strength and the compressive strength reach 96.2 and 198.3 MPa, respectively. The fabricated thermoelectric module reaches a competitive conversion efficiency of 6.8 % with ΔT = 200 K. These results provide a key contribution to the expansion of cogeneration devices in the field of low-grade waste heat recovery.