Relationship of Stokes shift with composition and structure in Ce3+ /Eu2+- doped inorganic compounds

The effect of chemical composition and structure on Stokes shift, an important luminescence property, has not been studied systematically. In this work, through statistical analysis of the structural and luminescent data of more than 60 compounds doped with Ce (3+) /Eu2+, the relationships between the Stokes shift, phonon energy, Huang-Rhys factor, chemical composition and structure of the compounds are revealed. Stokes shift has the positive correlation to the effective average coordination bond length R-av. It decreases in going through the halogenide series from fluorides to bromides, and the chalcogenides from oxides to selenides, respectively; while it is almost irrelevant of the anion types in the same period (nitrides, oxides, and fluorides). We also verify that the Stokes shift has no obvious correlation with coordination number of the cation. This paper provides a feasibility to predict the emission spectrum of Ce3+ /Eu2+ doped inorganic compounds and discover the suitable host lattice for required phosphors.