Luminescence and energy transfer mechanism in Sr9Sc(PO4)7: Ce3+, Mn2+ phosphor

A series of Ce3+ and Mn2+ co-doped Sr9Sc(PO4)7 phosphors have been synthesized by high temperature solid state reaction and their luminescence properties are investigated. The obtained phosphors exhibit a broad excitation band ranging from 240 to 350 nm and two emission bands centered at about 370 and 610 nm upon 310 nm excitation, resulting from the 5d–4f transitions of Ce3+ and the d–d forbidden transition of Mn2+, respectively. Energy transfer mechanism from Ce3+ to Mn2+ in Sr9Sc(PO4)7 host matrix was studied and demonstrated to be a resonant type via a dipole–dipole mechanism based on the decay lifetime data. Furthermore, we have calculated the critical distance for Ce3+→Mn2+ energy transfer to be about 6.12 Å by the spectral overlap method. Through effective energy transfer, a color-tunable emission varied from blue to reddish orange can be realized by adjusting the ratio of Ce3+ to Mn2+. Our results indicate the novel Sr9Sc(PO4)7: Ce3+, Mn2+ phosphor can be a promising candidate for a color-tunable phosphor applied in a UV white light emitting diodes.