Color-Tunable Emission and Energy Transfer in Ca 3 Gd 7 (PO 4 )(SiO 4 ) 5 O 2 : Ce 3+ /Tb 3+ /Mn 2+ Phosphors

Ce(3+)-, Tb(3+)-, and Mn(2+)-activated Ca(3)Gd(7)(PO(4))(SiO(4))(5)O(2) (CGPS) silicate-phosphate oxyapatite phosphors have been prepared via conventional solid-state reaction processes. The Ce(3+) emission at different lattice sites has been identified and discussed. The dual energy transfer of Ce(3+) → Tb(3+) and Ce(3+) → Mn(2+) has been investigated. The energy transfer from Ce(3+) to Mn(2+) in CGPS phosphors has been demonstrated to be a resonant type via a dipole-quadrupole mechanism, and the critical distances (R(C)) for Ce(3+) to Mn(2+) calculated by the concentration quenching and spectral overlap methods are 9.71 and 9.15 Å, respectively. A color-tunable emission in CGPS phosphors can be realized by Ce(3+) → Tb(3+) or Ce(3+) → Mn(2+) energy transfer. CGPS:0.05Ce(3+)/ 0.15Tb(3+) shows the optimum green emission. Meanwhile, white cathodoluminescence (CL) has been realized in a single-phased Ca(3)Gd(7)(PO(4))(SiO(4))(5)O(2) host by codoping with Ce(3+) and Mn(2+) with CIE (0.322, 0.326). Furthermore, the CL properties of CGPS:Ce(3+)/Tb(3+)/Mn(2+) phosphors, including the dependence of the CL intensity on the accelerating voltage and filament current, the decay behavior of the CL intensity under electron bombardment, and the stability of the CIE chromaticity coordinates, have been investigated in detail. Because of the good CL properties and good CIE chromaticity coordinates, the as-prepared phosphors have potential application in field emission display devices.