Simultaneous enhancement in thermoelectric performance and mechanical stability of p-type SiGe alloy doped with Boron prepared by mechanical alloying and spark plasma sintering

Abstract

Silicon-Germanium (SiGe) based alloys are the promising and an attractive thermoelectric candidate for radioisotope thermoelectric generators (RTGs) at high temperature (>1000 °C) application. Intensive efforts are being made to enhance the thermoelectric properties and mechanical stability of p-type SiGe alloy. The current work reports on synthesis of SiGe alloy doped with Boron (B) with varying concentration (0.5–2.0 at.%) through mechanical alloying (MA) followed by spark plasma sintering (SPS). The synthesised SiGe alloy doped with B1.5 at.% showcase the superior figure of merit (ZT) ̴ 0.525 at 800 °C which results in the significant enhancement of ∼9.38% than the p-type RTG SiGe alloy. The synthesised SiGe alloys exhibit an improvised thermoelectric compatibility factor of 0.968 V-1 (∼16% higher than RTG SiGe alloy). The SiGeB1.5 alloy demonstrated an ever-achieved physical robustness with the bench marked micro hardness of 9.93 ± 0.12 GPa and fracture toughness (KIC) of 2.36 ± 0.173 MPa√m (48% higher than SiGe alloy).