Synthesis and thermoelectric performance of Ni_0.3Co_3.7Sb₁₂ skutterudite filled with electronegative guest Se

Electronegative guests can be induced to fill the voids of skutterudite by doping electron donors in the framework of skutterudites. This method has been considered a promising method to improve thermoelectric properties. In this study, Se_yNi_0.3Co_3.7Sb₁₂ (y = 0, 0.025, 0.1, 0.125, 0.15) skutterudite compounds were prepared using a melt-quenching-annealing synthesis route and spark plasma sintering technology. The phase constituents, microstructure, thermoelectric properties, and thermal transport properties were investigated. Experimental results suggest that the charge compensation between Ni doping and Se filling has a positive effect on the formation of thermodynamically stable Se_yNi_0.3Co_3.7Sb₁₂ alloys. The existence of Se fillers in the voids reduces the lattice thermal conductivity. As the filling fraction of Se increases, the number of holes increases while the electron concentration decreases. The figure of merit (zT) of Se_0.15Ni_0.3Co_3.7Sb₁₂ reaches a maximum of 0.81 at 823 K.