The atomic environment and valence state of Ce implanted in Y2O3

Ce ions were implanted in Y2O3 Via x-ray absorption spectroscopy, Ce was fo und to occupy the Y site, and to be surrounded by oxygen atoms. However, co ntrary to what one would expect on the basis of this substitution, the oxid ation state was not purely trivalent Thanks to the Anderson impurity model, it was possible to interpret the x-ray absorption features near the edge. Ce is found in an intermediate charge state resulting from the interaction of the f state with the valence band of Y2O3.