Thermoelectric properties of the Ru2Ni2Sb12 ternary skutterudite

The synthesis of the Ru2−xNi2−xSb12 compounds (0≤x≤0.2), their structural characterization and temperature dependencies of selected transport and thermal properties are reported. At x=0, Ru2−xNi2−xSb12 displays cubic symmetry, space group Im3¯ with lattice parameter a=9.1767(1) Å. From increasing electrical conductivity above 600 K the band gap (Eg∼0.06 eV) was estimated using an Arrhenius plot. Different signs of the Seebeck coefficient (negative) and the Hall coefficient (positive) have been explained as a consequence of a multicarrier transport. The substitution on a cation site, i.e., formation of the Ru2−xNi2−xSb12 ternary skutterudites proved to be effective way in suppressing of the thermal conductivity. - Graphical abstract: Polyhedral representation of the Ru2Ni2Sb12 skutterudite crystal structure emphasizing the [(Ru/Ni)Sb6] corner-sharing octahedra. Highlights: ► Skutterudite-type structure with space group Im3¯ of the Ru2Ni2Sb12 was confirmed. ► The band gap of the studied compounds was estimated — Eg∼0.06 eV. ► Low lattice thermal conductivity of the Ru2Ni2Sb12 was observed.