Tb 3 + luminescence by energy transfer from Eu 2 + in ( Sr , Ba ) 2 SiO 4 phosphor

( Sr , Ba ) 2 SiO 4 phosphors co-doped with Tb 3 + and Eu 2 + were prepared by a conventional solid-state reaction method. Prepared ( Sr , Ba ) 2 SiO 4 : Tb , Eu phosphors had characteristic luminescent spectra excited under near-UV excitation in which both the broadband spectrum assigned to Eu 2 + and the narrowband spectrum assigned to Tb 3 + are observed, although Tb 3 + is inactive with this photon energy in general. The sudden emergence of the Tb 3 + luminescence shows that Eu 2 + - Tb 3 + energy transfer is possible in the phosphor. We also studied the energy transfer mechanism in terms of the resonant energy transfer theory and found that the crystal structure of the host material Sr 2 SiO 4 plays an important role in the luminescence properties of the phosphor. The Eu 2 + - Tb 3 + energy transfer is ascribed to the overlap between the shorter Eu 2 + luminescence band from the Sr 2 SiO 4 crystal structure with two Sr sites and D 5 4 energy level of Tb 3 + ion. Therefore, this phosphor has a potential for application to white light-emitting diodes excited by near-UV light.