An investigation was made, of the diffusion of Ce and O ions, by means of temperature programmed static secondary ion mass spectrometry. A (111) CeO2 film was grown heteroepitaxially, by means of molecular beam epitaxy, onto a Y2O3-stabilized ZrO2 substrate. High-quality low-energy electron diffraction patterns and Auger electron spectroscopy spectra, free of impurity signals, were obtained after only a few sputtering and annealing cycles but further cleaning was necessary in order to remove intense alkali and alkaline-earth signals. The (111) surface was slightly enriched in 18O by annealing the film under ultra-high vacuum at 830K, and then exposing the 130K crystal to 18O2. Temperature programmed static secondary ion mass spectrometry data, together with temperature programmed desorption data, demonstrated that surface O atoms began to be exchanged with the bulk at about 550K. The deposition of sub-monolayer amounts of isotopically (136Ce) enriched Ce in an 18O2 background permitted the simultaneous study of the diffusion of Ce and O. Surface Ce cations were found to be immobile, with no diffusion into the bulk at temperatures of up to 900K.

Self-Diffusion in Ceria. C.L.Perkins, M.A.Henderson, C.H.F.Peden, G.S.Herman: Journal of Vacuum Science & Technology A, 2001, 19[4], 1942-6