Luminescence of emission-tunable NaSr1-y-zBayCazPO4:Eu2+,Mn2+ phosphors for white LEDs

To develop new emission-tunable phosphors for white LEDs, a series of NaSr1-y-zBayCazPO4:Eu2+,Mn2+ (0 ≤ y ≤ 0.5, 0 ≤ z ≤ 0.3) phosphors were prepared by solid-state reaction method. For Eu2+-doped NaSr(PO4), the dominant emission band is located at 446 nm, and the optimal Eu2+ concentration is 0.3%. When the Ba2+ is doped into NaSrPO4:Eu2+, the Eu2+ emission band exhibits a blue-shift and the emission intensity is enhanced largely. When Ca2+ is doped, the emission band edge of Eu2+ shows a slight red-shift and that beyond 500 nm has been obviously increased. To obtain the tunable emission, Mn2+ is co-doped with Eu2+ in both NaSr0.5Ba0.5(PO4) and NaSr0.95Ca0.05(PO4), and the energy transfer from Eu2+ to Mn2+ was observed. The thermal stable luminescence in NaSr0.497Ba0.5(PO4):0.003Eu2+ and NaSr0.947Ca0.05(PO4):0.003Eu2+ is different. It is concluded that the NaSr1-y-zBayCazPO4:Eu2+,Mn2+ could be promising candidate for white LEDs.