Solvothermal synthesis of nano-sized skutterudite Co_1−xNi_xSb₃ powders

Abstract

Nanostructuring is one of the effective approaches to lower the thermal conductivity of thermoelectric materials for improving its figure of merit. The nano-sized uniform skutterudite Co 1− x Ni x Sb 3 ( x = 0, 0.05, 0.075, 0.125, 0.15, and 0.25) thermoelectric powders were synthesized in triethylene glycol solution by using CoCl 2 , NiCl 2 , and SbCl 3 as precursors and NaBH 4 as the reductant. Different synthesis conditions were studied to pursue pure and uniform skutterudite CoSb 3 powders. The powders were characterized by X-ray diffraction, field emission scanning electron microscope, and energy-dispersive X-ray analysis. Experimental results show that a Ni-doped skutterudite Co 1− x Ni x Sb 3 single phase was obtained at 290 °C for 12 h. The powders are spherical, small, and uniform. As x increases from 0 to 0.25, the unit-cell parameter a increases from 0.9044 to 0.9065 nm and the particle size increases from 10 to 30 nm.