Fabrication of nanostructured bulk Cobalt Antimonide (CoSb_3) based skuttcrudites via bottom-up synthesis

摘要

Skutterudites are known to be efficient thermoelectric (TE) materials in the temperature range from 600 K to 900 K. Dimensionless figure of merit (ZT) for filled skutterudite TE materials have been reported as ca. 1 at 800 K. Novel nano-engineering approaches and filling of the skutterudites crystal can further improve the transport properties and ultimately the ZT. Although classified among the promising TE materials, research on their large-scale production via bottom up synthetic routes is rather limited. In this work, large quantity of cobalt antimonide (CoSb_3) based skutterudites nanopowder (NP) was fabricated through a room temperature co-precipitation precursor method. Dried precipitates were process by thermo-chemical treatment steps including calcination (in air) and reduction (in hydrogen). CoSb_3 NPs were then mixed with silver (Ag) nanoparticles at different weight percentages (1%, 5% and 10% by wt) to form nanocomposites. Skutterudite NP was then consolidated by Spark Plasma Sintering (SPS) technique to produce highly dense compacts while maintaining the nanostructure. Temperature dependent TE characteristics of SPS'd CoSb_3 and Ag containing nanocomposite samples were evaluated for transport properties, including thermal conductivity, electrical conductivity and Seebeck coefficient over the temperature range of 300 - 900 K. Physicochemical, structural and microstructural evaluation results are presented in detail.