Warm-White-Emitting from Eu2+/Mn2+-Codoped Sr3Lu(PO4)3 Phosphor with Tunable Color Tone and Correlated Color Temperature

A series of single-component Sr3Lu(PO4)3:Eu2+,Mn2+ phosphors were successfully synthesized by solid-state reaction, and their photoluminescence properties were investigated. The Sr3Lu(PO4)3:Eu2+,Mn2+ phosphor system was efficiently excited at wavelength ranging from 250 to 420 nm, which is well-matched with ultraviolet (UV) light-emitting diode (LED) chips. As a result of fine-tuning of the emission composition of the Eu2+ and Mn2+ ions, warm white light emission can be realized by combining the emission of Eu2+ and Mn2+ in a single host lattice under UV light excitation. Efficient resonant energy transfer from the Eu2+ to Mn2+ ions was demonstrated to be a dipole–quadrupole mechanism in such system, and the energy transfer efficiency increases with an increase in the Mn2+ doping content, which was confirmed by the luminescence spectra and fluorescence decay curves. In addition, the energy transfer efficiency and critical distance were also calculated. The results indicate that the developed phosphor can be used as a potential white-light-emitting phosphor for white LEDs.