Impact of Eu3+ concentration on the fluorescence properties of the LiGd(W0.5Mo0.5O4)2 novel red phosphors

Abstract

Novel red emitting Eu3+ (y = 0.0–1.0) activated LiGd1-y(W0.5Mo05O4)2 phosphors were synthesized via polymeric complex sol-gel method. Powder X-ray diffraction (XRD) results and scanning electron microscope (SEM) micrographs of the phosphors reveal tetragonal crystalline structure and irregular sphere-like morphology for the particles with average size of 1–3 μm. Broad charge transfer band (CTB) in UV region and bright red emission for the electric dipole 5D0 → 7F2 transition at 615 nm was observed for Eu3+ activated tungsto-molybdate phosphors from the fluorescence excitation and emission results. These phosphors promote strong energy transfer from the (MoO4)2-/(WO4)2- groups to Eu3+ ions and lead to the strong enhancement in the intensity of red emission under 395 nm (near UV) excitation. Effect of Eu3+ activator concentration on the luminescence nature of the tungsto-molybdate solid solution and the critical concentration of activator Eu3+ for maximum red emission were investigated. Asymmetric ratio and the critical distance between the Eu3+ activator were calculated and decay scheme for the phosphors were determined. The conditions for intense red emission of the LiGd(W0·5Mo0·5O4)2:Eu3+ phosphors were optimized.