Synthesis and photoluminescence properties of Sm3+ doped LiGd(WO4)2 phosphors with high color purity

Abstract

A series of Sm3+:LiGd(WO4)2 phosphors with various concentrations of Sm3+ was prepared by the Pechini sol-gel method. The X-ray diffraction pattern of pure and Sm3+:LiGd(WO4)2 samples show the formation of LGW compound with tetragonal phase and a noticeable peaks shift toward lower angle with increasing Sm3+ concentration. The particles were of size 1–2 μm with irregular spherical and rectangular-like mixed morphology were witnessed from the scanning electron microscopy (SEM). X-ray photoelectron spectroscopy (XPS) spectrum of the doped sample depicts the presence of all the elements in the Sm3+ doped LiGd(WO4)2 compound. Board band excitation for CTB and the number of sharp excitation peaks for f-f transition were observed in excitation spectra. The emission spectra show sharp peaks at 562, 606, 645 and 701 nm due to transition from sm3+ ions. The optimal dopant concentration of Sm3+ ions and its critical distance in LiGd(WO4)2 matrix was calculated to be x = 0.01 and 3.0 nm for intense emission peak at 645 nm that corresponds to 4G5/2 → 6H9/2 transition of Sm3+ ions. The type of energy transfer interaction among Sm3+ was found as electric dipole-dipole interaction using the Dexter theory. CIE coordinates and color purity (CP) for reddish-orange emission of the Sm3+:LiGd(WO4)2 phosphors was determined to be (0.568, 0.425) and 82.4%, respectively. The observed properties of Sm3+:LiGd(WO4)2 proves its potential application for near UV based light-emitting diodes and optical display devices.