Thermoelectric properties of EuyCo4Sb12 filled skutterudites

Polycrystalline filled skutterudite compounds EuyCo4Sb12 with 0 ≤ y ≤ 0.6 are synthesized by melting method and sintered by spark plasma sintering technique. The crystallographic properties are characterized by X-ray diffraction and electron probe microanalysis. The maximal filling fraction of Eu in Co4Sb12 is experimentally determined to be as high as 60%, highest in all the rare-earth-impurity being able to fill into Co4Sb12 reported so far. The electrical conductivities, thermal conductivities and Seebeck coefficients of those samples are measured in the temperature range of 300–850 K, and the samples show n-type conduction. The lattice thermal conductivity is depressed significantly by Eu-filling, and a room temperature value of ∼1.8 W/m K for Eu0.34Co4Sb12 is obtained, which is the lowest one for ternary filled Co4Sb12 compounds reported so far. The dimensionless thermoelectric figure of merit, ZT, increases with increasing temperature and reaches a maximal value of 0.9 for Eu0.27Co4Sb12 at 850 K.

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