Photoluminescence and energy transfer of YAG: Ce3+, Gd3+, Bi3+

Abstract

In this study, Gd3+ and Bi3+ ions act to redshift the emission band to orange region, and to enhance significantly the maximum emission of YAG: Ce3+. On account that size mismatch between the host and the doped Gd3+ ion, the crystal structure turns soft, and the emission spectra are not tuned from 540 to 570 nm but decreased the emission intensity. Accordingly, an effective way to increase emission intensity is to introduce Bi3+ ion into the YAG: Ce3+, Gd3+ phosphors. Experimental results show partial overlapping between the emission band of Bi3+ ion and the excitation band of Ce3+ ion, indicating that the energy transfer from Bi3+ to Ce3+ ions exists in the (Y1.94Ce0.06Gd)Al5O12: Bi3+ phosphor. Bi3+ ion can serve as the activator to provide energy for Ce3+ ion via cross relaxation phenomenon. Therefore, the (Y1.94Ce0.06Gd)Al5O12: Bi3+ phosphor could have potential applications in warm white LEDs.