EFFECTS OF CRYSTAL-FIELD AND TEMPERATURE ON THE PHOTO-LUMINESCENCE EXCITATION EFFICIENCY OF CE3+ IN YAG

Absorption and luminescence spectra of YAG:Ce3+ crystals have been measured at various temperatures between 4.2° and 300°K. The high resolution, low temperature spectra show resolved fine structure. Zero-phonon transitions have been assigned and the phonon replicas correlated with lattice phonon energies. The characteristic absorption band of YAG:Ce3 + near 460 nm decreases in intensity, whereas that near 340 nm increases, with increasing temperature. This effect is explained in terms of a tetragonal crystal field splitting of both the 4P ground state and 5d1 excited states of Ce3+ in YAG. When allowance is made for changes in the absorption of pump light with temperature the photoluminescence quantum efficiency of Ce3 + in YAG is constant up to 300°K. The significance of these crystal field effects for the use of YAG: Ce as a high temperature lamp phosphor is discussed. © 1979, The Electrochemical Society, Inc. All rights reserved.