Synthesis and Luminescence Properties of La2O2S:RE3+ (RE3+ = Ce3+, Dy3+, Eu3+ and Tb3+) Submicron Size Phosphors for Lamp Industry

Abstract

RE3+(RE3+ = Ce3+, Dy3+, Eu3+ and Tb3+) doped La2O2S phosphors was synthesized by solid state flux fusion method and their down conversion spectral properties were studied as a function different RE3+ concentrations and reported in this paper. The solid state flux fusion results in well crystallized hexagonal shaped phosphor particles. The samples were characterized by XRD, SEM, FT-IR photoluminescence (PL) and CIE colour co-ordinates techniques. The lanthanum oxysulphide (La2O2S) phosphor doped with Ce3+ shows broad band emission with peak at 390 nm and 415 nm when excited at 340 nm excitation. La2O2S:Dy3+ shows efficient blue and yellow band emissions at 480 nm and 572 nm. La2O2S:Eu3+ phosphor shows an orange and red emission at 590 nm and 615 nm. Whereas La2O2S:Tb3+ phosphor shows weak blue emission at 488 nm and strong green 545 nm. The excitation spectra used for the La2O2S:RE3+ (where RE3+ = Ce3+, Dy3+, Eu3+ and Tb3+) phosphors is in the near UV region extending from 350 to 400 nm, which is characteristics of near UV excited LED. The effect of the RE3+ (RE3+= Ce3+, Dy3+, Eu3+ and Tb3+) concentration on the luminescence properties of La2O2S:RE3+ phosphors were also studied. The investigated prepared La2O2S phosphors may be suitable for a near UV excited W-LED. Keywords: Oxysulphide, SEM, FT-IR, PL, SSL, CIE.