Synergetic enhancement of thermoelectric and mechanical properties of n-type SiGe-P alloy through solid state synthesis and spark plasma sintering

Abstract

Silicon-germanium (SiGe) alloy is a potential and an attractive high temperature (>1000 °C) thermoelectric material used in space applications as radioisotope thermoelectric generators (RTGs). However, the lower figure of merit (ZT) is the main setback in the SiGe alloy, and a lot of research strategies are demonstrated to improve the performance. The current investigation details the fabrication of high dense (>99%) SiGe alloy doped with phosphorus (P) (0.5–2.0 at.%) by mechanical alloying (10 h) followed by spark plasma sintering (SPS). The synthesised SiGe-P2.0 at.% alloy demonstrates the enhanced ZT 1.03 at 750 °C. Concurrently, the superior hardness of 9.8 ± 0.17 GPa and fracture toughness (KIC) of 2.3 ± 0.15 MPa√m are achieved in SiGe-P1.5 at.% and SiGe-P2.0 at. % alloys, respectively.