High performance InxCeyCo4Sb12 thermoelectric materials with in situ forming nanostructured InSb phase

n-Type skutterudites InxCeyCo4Sb12 with in situ forming nanostructured InSb phase have been prepared by a melt-quench-anneal-spark plasma sintering method. Doping of In results in a nanostructured InSb phase with the grain size of 10-80 nm that is evenly distributed on the boundaries of the skutterudite matrix. The nanostructured InSb phase has a strong influence on phonon scattering and leads to a notable suppression of the lattice thermal conductivity of InxCeyCo4Sb12. The combined effect of In and Ce doping results in high performance skutterudite materials. The highest thermoelectric figure of merit ZT=1.43 is achieved at 800 K in the In0.2Ce0.15Co4Sb12 compound.