Low thermal conductivity and rapid synthesis of n-type cobalt skutterudite via a hydrothermal method

Abstract

We report low thermal conductivity for n-type cobalt skutterudites synthesized via a rapid hydrothermal procedure combined with evacuated-and-encapsulated heating. Different synthesis temperatures were investigated to obtain a single phase of CoSb₃. The resulting samples were characterized using X-ray diffraction, scanning electron microscopy, Hall and density measurements. A remarkably low thermal conductivity of 1.33–1.46 W m⁻¹ K⁻¹ at room temperature can be attained for the pristine CoSb₃, which is comparable with or even lower than that of the filled CoSb₃ obtained from solid state reaction. Regarding the requirement of lengthy annealing and reaction at high temperature using solid state reaction, our remarkably rapid and low temperature procedure fabrication together with significantly low thermal conductivity presents major progress in fabricating cobalt skutterudites using hydrothermal synthesis methods.