Investigation on luminescence of Na3Ca6(PO4)5:Eu2+ phosphor for LEDs

In this paper, a series of Na3Ca6(1−x)(PO4)5:xEu2+ (NCP:xEu2+, 0 ≤ x ≤ 4%) phosphors were prepared by conventional solid-state reaction method, and their photoluminescence properties were studied. Upon 365 nm excitation, the typical NCP:2%Eu2+ phosphor shows an asymmetric bluish green emission band with the dominant peak at 498 nm which could be attributed to the 4f65d1-4f7 transition of Eu2+. By measuring the time-resolved photoluminescence spectra, it reveals more than one Eu2+ emission center in the Eu2+-activated NCP phosphors. By monitoring 498 nm, the excitation spectrum of NCP:2%Eu2+ demonstrates a broad excitation band ranging from 240 to 450 nm, which can match well with the emission wavelength of the NUV LED chip. The SEM image shows that the average particle size of NCP:2%Eu2+ is about 19.4 µm. The above results imply that the NCP:Eu2+ phosphor could have potential application in LEDs.