Tunable Emission and Energy Transfer of the Novel KY_1-x(MoO₄)_2-y(WO₄)_{y:xLn³⁺ (Ln³⁺ = Dy³⁺, Eu³⁺, and Tm³⁺) Single-phase White Luminescence Phosphor for White LEDs}

The phosphors of KY1-x(MoO4)(2-y)(WO4)(y):xLn(3+) (Ln(3+) = Tm3+, Dy3+, Eu3+) were synthesized by using a sol-gel method. Then, the crystal structure, luminescence properties, energy transfer, and white emission of the prepared materials were researched. The molar ratio of the anion group on the photoluminescence(PL) emission and excitation intensity were investigated, revealing that the optimum intensity could be obtained by using = 3:1. The optimal Dy3+ doping concentration of KY(MoO4)(1.5)(WO4)(0.5) was obtained. In addition, the color-tunable emissions of Dy3+/Eu3+-codoped KY(MoO4)(1.5)(WO4)(0.5) phosphors were observed because of the effective energy transfer (ET) from Dy3+ to Eu3+ ions. Finally, by doping appropriate concentrations of Tm3+, Dy3+, and Eu3+ and different concentrations of (WO4)(2-), white light emitting phosphors KY0.92(WO4)(2):0.01Tm(3+).0.06Dy(3+), 0.01Eu(3+) with excellent color-rending properties were obtained. The chromaticity coordinate was calculated as (x = 0.3238, y = 0.3173), closing to the artificial daylight (D65, x = 0.313, y = 0.329) illuminant, and which indicates the potential application of near ultraviolet White light-emitting diodes (WLEDs).