Fast fabrication and enhancement of thermoelectric power factor of p-type nanostructured CoSb_3(1+δ) (δ=0.00, 0.01 and 0.02) using solvothermal synthesis and evacuating-and-encapsulating sintering

Nanostructured skutterudite p-type CoSb_3(1+δ) (δ=0.00, 0.01 and 0.02) samples are synthesized via a combination of solvothermal synthesis and evacuating-and-encapsulating sintering. All the samples are of single phase with cubic structure. The thermopower of all the samples is positive, indicating that the predominant carriers are hole in the temperature range of 300-700 K. Both the electrical resistivity and thermopower follow the variable range hopping process for 300≤T≤425 K. The power factor of all samples exhibits a monotonic increase with temperature up to 700 K. The highest power factor is obtained for CoSb_3(1+δ) with δ=0.01, which represents 145% increase when compared to CoSb₃ with δ=0.00. The ZT value is 0.07 at 550 K for CoSb_3(1+δ) with δ=0.01, representing an improvement of about 95% compared to CoSb₃ with δ=0.00. These results suggest that excess antimony provides an effective avenue of improving the thermoelectric properties of CoSb_3.