Electron energy loss spectroscopy study of cerium stabilised zirconia: An application of valence determination in rare earth systems

We have used the electron energy loss spectroscopy to study the valence state of cerium and the lattice distortion in Ce doped ZrO₂ ceramic from the fine structure in oxygen K-edge. We showed that the fine structure of Ce M_4,5 absorption edges is an excellent signature of the Ce valence state in the samples. This procedure is compared with other means of valence determination, such as white line intensity and branch ratio. Through the knowledge of the cerium oxidation state, we obtained information about the charge-compensating point defect in the samples. This is correlated with the distortion in the local atomic structure of zirconia. Our results showed the importance of covalent bonding for the phase-stabilisation mechanism in this ceramic system.