Enhancement of Phase Stability and Thermoelectric Performance of Meta‐Stable AgSbTe ₂ by Thermal Cycling Process

Abstract Thermoelectric materials are crucial components in thermoelectric devices employed for environmentally friendly solid‐state cooling and waste heat recovery, demanding not only high performance but also superior thermal or phase stability. The high‐performance thermoelectric material AgSbTe ₂ encounters challenges when utilized in thermoelectric modules due to the precipitation of Ag ₂ Te, resulting in both thermally unstable characteristics and diminished performance. In this study, a thermal cycling process is employed to enhance the thermal stability and thermoelectric performance of AgSbTe ₂ . Through thermal cycling, secondary phases of AgSbTe ₂ are made uniform, and the undesired Ag ₂ Te is substituted with Sb ₂ Te ₃ using an optimized thermal cycling process. As a result, the thermal stability of AgSbTe ₂ is enhanced due to its meta‐stable state, with <5% variance in thermoelectric figure of merit (ZT) measurements, and the ZT value is raised from 0.8 to 1.7 at 643 K through the optimized thermal cycling. The findings indicate that thermal cycling is an effective strategy for enhancing the thermal stability and thermoelectric performance of AgSbTe ₂ , presenting a novel approach for achieving uniform secondary phases in materials with phase separation or phase change characteristics.