Fluorescence of Eu3+-Activated Lanthanide Oxyhalides LnOX

Abstract

The fluorescence of Eu³⁺‐activated lanthanide oxyhalides LnOX (Ln=Y, La, Gd, and X=Cl, Br) is reported. Although all host lattices under consideration are isomorphous, the spectral energy distribution of the Eu³⁺ emission depends strongly on the choice of X and to a lesser extent on that of Ln. This variation is accounted for qualitatively by assuming a strongly varying linear component of the crystal field. The excitation spectra of the Eu³⁺ fluorescence and the diffuse reflection spectra are also dependent on the choice of Ln and X. The quantum efficiency of GdOCl: Eu and YOCl: Eu is high (about 60%—70%).