Tunable luminescence and energy transfer process between Tb 3+ and Eu 3+ in GYAG:Bi 3+, Tb 3+, Eu 3+ phosphors

Abstract

A series of Eu 3+ ions co-doped (Gd 0.9Y 0.1) 3Al 5O 12:Bi 3+, Tb 3+ (GYAG) phosphors have been synthesized by means of solvothermal reaction method. The XRD pattern of GYAG phosphor sintered at 1500 °C confirms their garnet phase. The luminescence properties of these phosphors have been explored by analyzing their excitation and emission spectra along with their decay curves. The excitation spectra of the GYAG:Bi 3+, Tb 3+, Eu 3+ phosphors consists of broad bands in the shorter wavelength region due to 4f 8 → 4f 75d 1 transition of Tb 3+ ions overlapped with 6s 2 → 6s 16p 1 ( 1S 0 → 3P 1) transition of Bi 3+ ions and the charge transfer band of Eu 3+–O 2−. The present phosphors exhibit green and red colors due to 5D 4 → 7F 5 transition of Tb 3+ ions and 5D 0 → 7F 1 transition of Eu 3+ ions, respectively. The emission was shifted from green to red color by co-doping with Eu 3+ ions, which indicate that the energy transfer probability from Tb 3+ to Eu 3+ ions are dependent strongly on the concentration of Eu 3+ ions.