Photoluminescence properties of the high-brightness Eu3+-doped KNaCa2(PO4)2 phosphors

Abstract

A series of red-emitting phosphors Eu3+-doped KNaCa2(PO4)2 were synthesized by solid-state reaction, and the photoluminescence (PL) properties were also investigated. The excitation spectrum is composed of charge-transfer (CT) of Eu–O and excitation lines of Eu3+ ions. The strongest excitation lines appeared at 393nm. The emission spectra of KNaCa2(PO4)2:Eu3+ phosphors exhibit five peaks assigned to the 5D0–7FJ (J=0, 1, 2, 3, 4) transitions of Eu3+ and have dominating emission peak at 621nm under 393nm excitation. The luminescence intensity enhanced with increasing Eu3+ content and the emission reached the maximum intensity at x=0.02 in KNaCa2−x(PO4)2:xEu3+. The effect of the charge compensators on the emission intensity of the phosphors was investigated. The integral intensity of the emission spectrum of KNaCa1.96(PO4)2:0.02Eu3+, 0.02Na+ excited at 393nm is about 2.4 times as strong as that of Y2O3:0.05Eu3+ commercial red phosphor. The color coordinates for KNaCa1.96(PO4)2:0.02Eu3+,0.02Na+ were measured. The results indicate that KNaCa2(PO4)2:Eu3+ might be a promising phosphor for w-LEDs.