Conductivity measurements were performed on singly- and doubly-doped ceria compounds. The materials used were of the form: Ce0.8Ln0.2O1.9, where Ln was Y, Sm, Nd or La, and Ce0.8Ln0.1Y0.1O1.9. The lattice constants of the compounds were proportional to the ionic radius of the dopant. The doubly-doped ceria compound exhibited an oxide ionic conductivity which was comparable to the average of that of each corresponding singly-doped sample. This indicated that the conductivity was affected by both dopants in doubly-doped compounds. Extended X-ray absorption fine structure studies showed that the coordination number of oxide ions at the nearest neighbor of the cation was related to the ionic conductivity. It was found that the conductivity took its highest value when O vacancies were randomly distributed within the lattice. It was concluded that the local structure strongly affected oxide ionic conduction in singly- and doubly-doped ceria compounds.

Investigation of the Relationship between the Ionic Conductivity and the Local Structures of Singly and Doubly Doped Ceria Compounds Using EXAFS Measurement. H.Yoshida, H.Deguchi, K.Miura, M.Horiuchi, T.Inagaki: Solid State Ionics, 2001, 140[3-4], 191-9