Compositional heterogeneity in ceria-based mixed oxides observed by x-ray photoelectron spectroscopy

It is argued that compositional heterogeneity in certain reducible mixed ox ides, like Ce1-xZrxO2, can be inferred from a variation in the metals ratio , as measured by x-ray photoelectron spectroscopy, between fully oxidized a nd partially reduced states of the oxide, provided that the characteristic linear dimension of the heterogeneity is at least as large as the typical e lectron inelastic mean-free path. The argument is supported by experimental results from two examples involving mixed phases, one in which the length scale is 100 nm and the other in which the domains are too small for detect ion by standard x-ray diffraction. (C) 2000 American Vacuum Society. [S0734-2101(00)01304-X].