Boosting thermoelectric performance of p-type SiGe alloys through in-situ metallic YSi2 nanoinclusions

Incorporation of metallic yttrium silicide nanoparticles in p-type SiGe alloys matrix is demonstrated to enhance their thermoelectric performance. In this work, we report a thermoelectric figure-of-merit (ZT) of ~1.81 (at 1100 K) in p-type SiGe alloys (that is ~34% higher as compared to earlier best reported ZT value) by intentional incorporation of metallic yttrium silicide (YSi2) nano-inclusions. The YSi2 nanoinclusions were in-situ formed in p-type SiGe matrix by its reaction with Y2O3 nanoparticles (≤6 wt%) during vacuum hot pressing at 1423 K under a pressure of 50 kg/cm2. YSi2 nanoinclusions form coherent interfaces with SiGe matrix and facilitate a reduction in the grain size of SiGe. These factors cause a strong suppression of thermal conductivity (κSiGe~3.86 Wm−1 K−1 and κSiGe-YSi2~2.38 W m−1 K−1 at 1100 K) without affecting the power factor, and therefore, results in a dramatic enhancement of ZT. In addition, SiGe-YSi2 nanocomposites exhibit enhancement in mechanical hardness, enhanced average ZT as well as compatibility factor, which are additional useful characteristics for practical applications.