Synthesis and luminescence properties of NaAl11O17:Mn2+ green phosphor for white LEDs

Novel NaAl11O17:Mn2+ green phosphor is synthesized by solid-state reaction method in air. The emission band peaking at similar to 508 nm is observed owing to the T-4(1)->(6)A(1)(S-6) transition of Mn2+ ion, and the chromaticity coordinates are (0.0725, 0.6468). The excitation band peaking at similar to 360, 382, 424, 450, and 490 nm are attributed to (6)A(1)(S-6)-> E-4(D-4), T-4(2)(D-4), [(4)A(1)((4)G), E-4((4)G)], T-4(2)((4)G), and T-4(1)((4)G) transitions of Mn2+ ion, respectively, which indicate that NaAl11O17:Mn2+ phosphor may be excited by (near) ultraviolet and blue LED chip. The luminous mechanism is explained by Tanabe-Sugano diagram of Mn2+ ion. The optimal Mn2+ doping concentration is similar to 3.5 mol%. The NaAl11O17:3.5%Mn2+ phosphor shows high quantum efficiency of similar to 67.84% with excitation 424 nm. The lifetime decreases from 6.72 to 6.0 ms with increasing Mn2+ concentration in the range of 0-4 mol%. (C) 2016 Elsevier B.V. All rights reserved.