Rare Earth doped ceria: a combined X-ray and neutron pair distribution function study

Rare Earth doped ceria materials (Ce1-xRExO2-x/2) are widely studied for their application in solid oxide fuel cell devices. In this work, RE(Yb, Y, Nd, La)-doped ceria samples at constant (x = 0.25) doping rate were subjected to a combined synchrotron radiation and neutron powder diffraction study. The dopants were chosen in order to cover a wide range of dopant-ionic radii. The effect of doping on the average structure is investigated using conventional Rietveld analysis, while the Pair Distribution Function technique is used to explore the spatial extent of disorder as well as the local structure. Two models for mapping the local structure, in terms of oxygen relaxation and nano-phase separation, are presented.