Energy transfer and color-tunable luminescence properties of YVO4:RE (RE = Eu3+, Sm3+, Dy3+, Tm3+) phosphors via molten salt synthesis

Abstract

Single-phased YVO4:RE (RE = Eu3+, Sm3+, Dy3+, Tm3+) phosphors with high efficient photoluminescence properties have been successfully synthesized using NaNO3 as molten salt by the molten salt synthesis (MSS) method. The formation of a single YVO4 phase has been confirmed by X-ray diffraction (XRD) and the photoluminescence spectra of these phosphors have been characterized using photoluminescence spectroscopy. The results indicated that all phosphors showed rare earth ion characteristic emissions (Eu3+, Sm3+, Dy3+, Tm3+) in the YVO4 host. The dependency of the luminescence intensity on doping concentrations and annealing temperatures of YVO4:Eu3+ and YVO4:Sm3+ phosphors has been discussed. It was found that the emission of YVO4:Sm3+ at 647 nm due to 4G5/2 → 6H9/2 transition of Sm3+ ions was improved drastically by the MSS method, more than other methods. Moreover, the emission colors are tuned from blue to white and ultimately to yellow through concentration variation of the doping concentration ratio of Tm3+ and Dy3+ in YVO4:Dy3+/Tm3+, and a white light could be achieved from YVO4:1% (Dy0.3Tm0.7) phosphor with chromaticity coordinates of (0.32, 0.31) under excitation at 320 nm.