Color-tunable properties and energy transfer in Ba3GdNa(PO4)3F:Eu2+, Tb3+ phosphor pumped for n-UV w-LEDs

A series of Eu2+ and Eu2+/Tb3+ co-doped Ba3GdNa(PO4)(3)F phosphors have been synthesized via a high temperature solid-state reaction. The relative intensity of PL spectra of Ba3GdNa(PO4)(3)F:xEu(2+) increases with increasing x value, and reaches a maximum at x=0.04. Ba3GdNa(PO4)(3)F:Eu2+, Tb3+ phosphors exhibit a broad excitation band ranging from 220 to 450 nm, which matches perfectly with the characteristic emission of n-UV light-emitting diode (LED) chips. Upon 365 nm excitation, the Ba3GdNa(PO4)(3)F:Eu2+, Tb3+ phosphors show two dominating bands peaked at 466 and 543 am, which are assigned to the 4f(7)-> 4f(6)5d(1) transition of the Eu2+ ions and the D-5(4)-> F-7(5) transition of the Tb3+ ions, respectively. In view of the energy transfer mechanism between Eu2+ and Tb3+, the Ba3GdNa(PO4)3F:Eu2+, Tb3+ emission color can adjust from blue to green, and their chromatic coordinates (x, y) vary from (0.16, 0.135) to (0.254, 0398). The critical distance was also calculated to be 16.90 angstrom. The above results indicate that the Ba3GdNa(PO4)3F: Eu2+, Tb3+ phosphors are a candidate for bluegreen components in the application of n-UV w-LEDs. (C) 2015 Elsevier Ltd. All rights reserved.