Thermal and mechanical stability of microwave sintered cold compact bismuth telluride thermoelectric material

Abstract

Both p-type and n-type bismuth telluride (Bi2Te3)-based thermoelectric materials demonstrate high thermoelectric efficiency in the low-temperature thermoelectric modules, but their constrained thermal and mechanical stability restrict their commercial applications. In our current work, we report the thermal and mechanical properties of both p-type and n-type bismuth telluride-based thermoelectric materials prepared by the cold compaction method. The compacted pellets were sintered in a microwave at 250 °C and 300 °C. Thermogravimetric analysis (TGA), and differential scanning calorimeter (DSC) analysis were performed to study the thermal stability, and nanoindentation, compression test, and microhardness tests were done for mechanical stability. The TGA-DSC results indicate a slight mass gain at 350 °C followed by a steep weight loss beyond 550 °C suggesting good thermal stability when the experimental temperature is below 350 °C. The hardness values decreased with an increase in the sintering temperature. The compression strength for all the samples had almost a constant value of 64 ± 0.5 MPa. Our fabrication method has the benefits of a low-cost, simple, and quick process paired with better thermal and mechanical properties, making it a good prospect for bismuth telluride thermoelectrics.