Exploration of synthesis route and effect of Ni-doping on thermoelectric performance of CoSb3

Abstract

CoSb3-based materials have surfaced as promising contenders for mid-temperature thermoelectric (TE) applications owing to their low cost and stability. The current work focuses on designing three different synthesis routes and their comparison to find out the most suitable route for synthesizing pristine CoSb3. The designed synthesis routes are direct spark plasma sintering (SPS), conventional furnace melting followed by SPS, and arc melting followed by SPS. Based on structural and transport characterizations, the synthesis route of arc melting followed by SPS was handpicked amongst the three different synthesis routes. The key benefit of this synthesis route is the massive reduction in synthesis time and efforts without compromising the TE performance. Finally, to analyze the effectiveness of the optimized synthesis route, Ni-doped CoSb3 alloys were also synthesized, and the properties were studied. The effect of “Ni doping” on TE properties of CoSb3 alloys, resulted in n-type conduction, and an enhanced figure-of-merit (ZT) ∼0.61 at around 870 K for optimized composition Ni0.07Co0.93Sb3.