Structural, spectroscopic and photolurninescence studies of LiEu(WO4)(2-x)(MoO4), as a near-UV convertible phosphor

Abstract

A series of lithium europium double tungsto-molybdate phosphors LiEu(WO4)(2-),(MoO4), (X = 0, 0.4, 0.8, 1.2, 1.6, 2.0) have been synthesized by solid-state reactions and their crystal structure, optical and luminescent properties were studied. As the molybdate content increases, the intensity of the D-5(0) -> F-7(2) emission of Eu3+ activated at wavelength of 396 mn was found to increase and reach a maximum when the relative ratio of Mo/W is 2:0. These changes were found to be accompanied with the changes in the spectral feature, which can be attributed to the crystal field splitting of the D-5(0) -> F-7(2) transition. As the molybdate content increases the emission intensity of the 615 nm peak also increases. The intense red-emission of the tungstomolybdate phosphors under near-UV excitation suggests them to be potential candidate for white light generation by using near-UV LEDs. In this study the effect of chemical compositions and crystal structure on the photolumineseent properties of LiEu(WO4)(2-x)(MoO4), is investigated and discussed. (c) 2006 Elsevier Inc. All rights reserved.