Luminescent properties of red-emitting LiSr4B3O(9−3x/2)Nx:Eu2+ phosphor for white-LEDs

An Eu2+-activated oxynitride LiSr(4−y)B3O(9−3x/2)Nx:yEu2+ red-emitting phosphor was synthesized by solid-state reactions. The synthesized phosphor crystallized in a cubic system with space group Ia–3d. The LiSr4B3O(9−3x/2)Nx:Eu2+ phosphors exhibited a broad red emission band with a peak at 610 nm and a full width at half maximum of 106 nm under 410 nm excitation, which is ascribed to the 4f65d1→4f7 transition of Eu2+. The optimal doped nitrogen concentration was observed to be x=0.75. The average decay times of two different emission centers were estimated to be 568 and 489 ns in the LiSr3.99B3O8.25N0.5:0.01Eu2+ phosphors, respectively. Concentration quenching of Eu2+ ions occurred at y=0.07, and the critical distance was determined as 17.86 Å. The non-radiative transitions via dipole–dipole interactions resulted in the concentration quenching of Eu2+-site emission centers in the LiSr4B3O9 host. These results indicate LiSr4B3O(9−3x/2)Nx:Eu2+ phosphor is promising for application in white near-UV LEDs.