In-situ synthesis of n-type unfilled skutterudite with reduced thermal conductivity by hybrid flash-spark plasma sintering

Abstract

N-type skutterudite Ni0.15Co0.85Sb3 was obtained using a reactive sintering process using a derivative of the Spark Plasma Sintering (SPS) method (hybrid Flash-SPS). This used extremely high heating rates (9000 °C/min) to reach a temperature of 750 °C. This new technique produced in a short time (<10 min) dense and nearly single-phase skutterudite. The material showed reduced thermal conductivity (2.5 W/m*K) and almost unchanged electrical properties when compared to a conventional SPSed sample; the ZT was 0.81 at 550 °C. It is also shown that the high heating rate, not the holding time, was the origin of these improvements.