Warm-white-light emission from Eu2+/Mn2+ -coactivated NaSrPO4 phosphor through energy transfer

A series of white-light-emitting NaSrPO4:Eu2+, Mn2+ phosphors were successfully synthesized by solid-state reaction and their photoluminescence properties were investigated. The NaSrPO4:Eu2+, Mn2+ phosphor system exhibits a broad excitation band in the wavelength range of 250–420 nm, which is well-matched with ultraviolet (UV) light-emitting-diode (LED) chips (typically 365 nm). As a result of fine-tuning of the emission composition of the Eu2+ and Mn2+ ions, warm-white-light emission can be realized in a single host lattice under 365 nm excitation. Efficient resonant energy transfer from the Eu2+ to Mn2+ ions has been observed. The energy transfer efficiency and critical distance were calculated. The results indicate that the developed phosphor can be used as a potential candidate for white LEDs.