Single-phase tunable white-light-emitting Sr_3 La(PO_4)_3 : Eu^2+, Mn^2+ phosphor for white LEDs

A novel, near-ultraviolet-excited white-light-emitting phosphor Sr3La(PO4)3:Eu2+, Mn2+ was synthesized by the solid-state method. Luminescence properties and the energy transfer mechanism were investigated in detail by photoluminescence spectra and decay curves. With the energy transfer between Eu2+ and Mn2+, a cold white light with chromaticity coordinates of (0.2790, 0.2273), correlated color temperature of 6501 K, Ra of 70, and external quantum efficiency of 35.5% was realized by changing the ratios of Eu2+ and Mn2+ in the Sr3La(PO4)3:Eu2+, Mn2+ phosphors. Resonant energy transfer from Eu2+ to Mn2+ ions has been demonstrated to be a dipole–dipole mechanism in Sr3La(PO4)3. The energy transfer efficiency increases with Mn2+ concentration increasing, and reaches a maximum of 55.6%.