Tracer diffusion coefficient and surface exchange coefficient values were found for high-temperature tetragonal scheelite-structured CeNbO4+δ (monoclinic fergusonite at room temperature). This was of interest due to its wide range of O stoichiometries; varying from stoichiometric CeNbO4 to CeNbO4.33. Measurements of the tracer diffusion coefficient and of the surface exchange coefficient were performed by using the isotopic exchange/line scan technique, with secondary ion mass spectrometry being used to determine the 18O stable isotope depth distribution. This was carried out at 1073 to 1173K under 500mbar of 16O/18O. These data were then correlated with oxide-ion conductivity data previously determined using 4-probe direct-current and emf measurements and the Nernst–Einstein relationship.

Diffusion and Conductivity Properties of Cerium Niobate. R.J.Packer, E.V.Tsipis, C.N.Munnings, V.V.Kharton, S.J.Skinner, J.R.Frade: Solid State Ionics, 2006, 177[19-25], 2059-64