The influence of sintering temperature on the thermoelectric and mechanical performance of n-type Mg3Sb2-based materials

Abstract

n-Type Mg₃Sb₂-based materials are promising for thermoelectric applications owing to their cost-effectiveness, environmental friendliness, and facile synthesis. Increasing the sintering temperature is an effective method for improving low-temperature thermoelectric performance, but its impact on the mechanical properties has not been adequately studied. This work systematically investigates the influence of sintering temperature on the thermoelectric and mechanical properties of Mg_3.2Pr_0.03Sb_1.5Bi_0.5. Attributed to improved carrier mobility, the room-temperature ZT value of the sample sintered at 1123 K (0.24) is doubled compared to that of the sample sintered at 923 K (0.12). However, the highest peak ZT of ∼1.65 at 725 K is achieved in the 923 K sintered sample. In terms of mechanical properties, the 923 K sintered sample demonstrates better overall performance, with a Vickers hardness of 1.17 GPa and a fracture toughness of 1.10 MPa m^1/2. In comparison, the hardness and fracture toughness of the 1123 K sintered sample decrease by 24% and 5%, respectively, which is likely due to the weakening of fine-grain strengthening. This work reveals the correlation between microstructure and mechanical properties, providing guidance for the synergistic optimization of thermoelectric and mechanical performance of the material.