Synthesis and luminescent properties of novel Li1.0Nb0.6Ti0.5O3: Dy3+ phosphors for white light-emitting diodes

Abstract

Novel Li1.0Nb0.6Ti0.5O3: xDy3+ white-emitting phosphors were synthesized by two methods, the solid-state reaction method and the sol-gel method. The effects of the preparation method, processing temperature and rare earth ion concentration on the luminescence properties of the samples were studied systematically in this paper. The phosphors prepared by two methods have the same orthorhombic “M-phase” solid solution structures and the particle sizes are in the scope of 1.5–2.5 μm. Under an excitation of 390 nm, the photoluminescence peaks of all samples were concentrated at 484 nm and 582 nm, related to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 electron transitions of Dy3+ ions. With the doping concentration of Dy3+ increasing, the luminescence intensities of Li1.0Nb0.6Ti0.5O3: xDy3+ phosphors reach its relative maximum at x = 2 wt%. Moreover, the optimal calcination temperature of the samples prepared by the sol-gel method is about 850 °C, which is 200 °C lower than that of solid-state reaction method. The color coordinates of the phosphors prepared by two methods were confined to white light region, closed to the standard white coordinates. These results lay solid foundation for the promising application of Li1.0Nb0.6Ti0.5O3: Dy3+ as phosphors in white light-emitting diodes.