LOCAL ELECTRONIC-STRUCTURE OF CE-DOPED Y2O3 - AN XPS AND XAS STUDY

An experimental study of the local electronic structure of Ce-doped yttria (2% and 5% at.) was performed using photoelectron and x-ray-absorption spectroscopies (XPS and XAS). The local atomic arrangement in the solid solutions is well represented by an eightfold oxygen coordination around Ce atoms, with a Ce-O distance shorter than in CeO2 (2.28 angstrom as Y-O instead of 2.34 angstrom). The x-ray-absorption spectra measured at the Ce L3 edge and the Ce 3d photoelectron lines are characteristic of the CeO8 environment, as in CeO2. However, the changes observed in the excitation spectra of the solid solutions are characteristic of an increase of the charge-transfer energy, due to the shortening of the Ce-O distance. The oxygen K-edge spectra evidence the existence of extended unoccupied f-character states, characteristic of tetravalent Ce.