Sr3GdNa(PO4)(3)F:Eu2+,Mn2+: a potential color tunable phosphor for white LEDs

A series of Eu2+ and Mn2+ activated novel Sr3GdNa(PO4)(3)F phosphors have been prepared through a high temperature solid state reaction. The investigation revealed that Sr3GdNa(PO4)(3)F crystallized in a hexagonal crystal system with the space group P (3) over bar (no. 147). The Eu2+ activated phosphors can be efficiently excited in the range of 250 to 420 nm, which matches well with the commercial n-UV LED chips, and give intense blue emission centering at 470 nm. By codoping the Eu2+ and Mn2+ ions into the SGNPF host and singly varying the doping content of the Mn2+ ion, tunable colors from blue to white and then to yellow are obtained in SGNPF: Eu2+, Mn2+ phosphors under the irradiation of 390 nm. The energy transfer from the Eu2+ to Mn2+ ions is demonstrated to be a dipole-quadrupole mechanism in terms of the experimental results and analysis of photoluminescence spectra and decay curves of the phosphors. The critical distance between the Eu2+ and Mn2+ ions in SGNPF: Eu2+, Mn2+ was determined by the spectral overlap method. The investigation indicates that our prepared samples might have potential application in WLEDs