The thermoelectric properties of (Ce,La)yFe1.0Co3.0Sb12 compounds by solid state reaction and spark plasma sintering

Filled skutterudite compounds (Ce,La)_yFeCo₃Sb₁₂ with y=0.1∼0.3 were synthesized by solid state reaction-spark plasma sintering (SPS) using powders of Co, Sb, Fe and rare earth Ce as starting materials, and the thermoelectric properties of the compounds were also studied. It is shown that there is a little Sb in filled skutterudite compounds (Ce,La)_yFeCo₃Sb₁₂ with y=0.1∼0.3 at 900 K. The lattice constant and the Seebeck coefficient of the compounds increases with the filling fraction of the Ce and La, while the thermal conductivity and electrical conductivity is greatly reduced The compounds had a minimum value of thermal conductivity with y=0.3, indicating that it is the coupling rattling and the irregular distribution between the two filler ions of La and Ce that give rise to the mass change of atom and the additional phonon scattering produced by lattice aberration when the Sb voids in the skutterudite structure were filled by Ce and La. The compound of Ce_0.1La_0.2Fe_1.0Co_3.0Sb₁₂ with Co-rich had a maximum value of the dimensionless figure of merit ZT=0.46 at 773 K.