Relationship of 5d-level energies of Ce3+ with the structure and composition of nitride hosts

The host structure and composition of rare earth doped phosphors play important roles in tuning luminescence properties. The energy of the 5d levels of Ce3+ in nitrides has recently become available due to the development of nitride phosphors. In this work, we have collected information on 5d levels of Ce3+ in nitrides and obtained a linear relationship between the anion polarizability and the inverse square of the average electronegativity of the cations based on the Dorenbos model. Our result indicates that the magnitude of the centroid shift can be predicted not only in nitrides but also in oxynitrides. Furthermore, the local structural features of Ce3+ can be unveiled on the basis of excitation luminescence spectra; as an example, we show that Ce3+ ions occupy the Sr2+ site rather than the Y3+ site in SrYSi4N7 compound.