Luminescent properties of novel K3R(PO4)2:Tb3+ (R=Y and Gd) phosphors for displays and lightings

Abstract

K3R(PO4)2:Tb3+ (R=Gd and Y) phosphors were prepared by a solid-state reaction method, and their photoluminescence (PL) and cathodoluminescence (CL) properties were investigated. The excitation in vacuum ultraviolet (VUV) region of K3Gd0.3(PO4)2:0.7Tb3+ and K3Y0.3(PO4)2:0.7Tb3+ show broad bands in 125–238nm, which can match the VUV light sources of 147 and 172nm for plasma display panels and Hg-free lamps. The 4f–4f5d spin-allowed and spin-forbidden transitions of Tb3+ are verified to be located around 233 and 264nm, respectively. Both series of phosphors exhibit strong green emissions with the predominated peaks at 545 and 544nm under 147 and 367nm excitation, respectively, corresponding to the 5D4→7F5 transition of Tb3+. Under the same conditions, the relative luminance of this phosphor is about 75%, 70% of that of commercial phosphor Zn2SiO4:Mn2+ (ZSM) under 147nm VUV light, the VUV sensitization of Tb3+ emission by Gd3+ in K3GdY(PO4)2:Tb3+ and the possible VUV luminescence mechanism are investigated. In addition, the CL spectra of K3R(PO4)2:Tb3+ (R=Y and Gd) exhibit Tb3+ characteristic emissions and strong intensities. The above results indicate that K3R(PO4)2:Tb3+ (R=Y and Gd) could be potential candidates as green-emitting VUV and CL phosphors.