5d-level energies of Ce3+ and the crystalline environment. III. Oxides containing ionic complexes - art. no. 125117

Information on the energy of 5d levels of Ce3+ ions coordinated by CO32-, S O42-, PO33-, BO33-, and SiO44- ionic complexes or by neutral water molecule s in oxide compounds will be presented and systematically analyzed. The ave rage energy of the 5d configuration of excited Ce3+ is shifted towards lowe r energy relative to the free ion value. This centroid shift depends on the binding strength of the oxygen ligands in these ionic complexes. It will b e analyzed by means of a model which provides a parameter that is directly related to the polarizability of the oxygen ligands. A qualitative relation ship with the electronegativity of the cations in the compounds will be dem onstrated. Crystal-field splitting of the 5d levels is interpreted in terms of the type and size of anion polyhedron coordinating the Ce3+ ion. All da ta indicate that crystal-field splitting behaves independently from the cen troid shift. By combining centroid shift and crystal-field splitting, the r edshift of the first electric dipole-allowed fd transition in Ce3+-doped ox ide compounds will be interpreted.