Neutron study of rare earth filling and physical properties in Ry(Fe,Ni)4Sb12 (with R=La or Ce)

Partially filled skutterudites have attracted a lot of attention in the last years notably because these compounds can be synthesised in large composition ranges and can easily be substituted. Our study is focussed on the series Ce_yFe_4-xNi_xSb₁₂ with the aim to understand how the Ce filling fraction influences the electronic and thermal properties. Two main results emerge from the present work. In the series with y=4/3-2×/3, it appears that the network can´t fully accommodate the cerium content for high values of y, resulting in metallic-type electronic transport properties. Secondly, thermal expansions measured by neutron diffraction show that the Debye temperature is reduced with increasing cerium content supporting a more complex picture than originally thought.