Ca8NaY(PO4)6F2:Eu2+,Mn2+: a potential color-tunable phosphor for white LEDs applications

Eu2+- and/or Mn2+-activated Ca8NaY(PO4)(6)F-2 phosphors have been prepared via a combustion-assisted synthesis route. The powder X-ray diffraction measurement revealed that Ca8NaY(PO4)(6)F-2 crystallized in a hexagonal crystal system with the space group P6(3)/m (176). The photoluminescence spectrum of the Eu2+ single-doped phosphor shows a broad blue emission band peaking at 451 nm under the excitation of UV irradiation. The Eu2+-/Mn2+-codoped phosphors show a blue emission band and an orange emission band, and the corresponding CIE coordinates intuitively indicate the tunable colors from blue to yellow area. The energy transfer from the Eu2+ to Mn2+ ions is demonstrated to be a quadrupole-quadrupole mechanism in terms of the experimental results and analysis of PL spectra and decay curves of the phosphors. The developed phosphors can be efficiently excited in the UV region and exhibit a tunable white-light emission, making them attractive as single-component white-light-emitting conversion phosphors for UV-based white LEDs.