Tunable Emission Color, Energy Transfer Mechanisms And High Thermal Stability of Tm 3+ /Dy 3+ Co-Doped Single-Component White Luminescent Tungstate Phosphors

Single-component white phosphors have broad application prospects in phosphor-converted white light emitting diodes (pc-WLEDs). Herein, a series of novel single-phase Tm3+/Dy3+ doped Na5Lu(WO4)4 phosphors were prepared. The phase purity and structures were characterized by XRD and analyzed by Rietveld refinement, which revealed the pure tetragonal phase for successful doping and repeatable preparation. Detailed investigation of its luminescence behavior showed that the luminescence color of Na5Lu(WO4)4:9%Tm3+,yDy3+ phosphors could be tuned from blue (0.15422,0.02567) to yellowish white (0.35926,0.37956) by the Tm3+→Dy3+ energy transfer process at 365 nm excitation, of which the emission color of Na5Lu(WO4)4:9%Tm3+,5%Dy3+ were very close to standard white light. According to the concentration-dependent emission spectra results, the electric dipole-dipole interaction was dominant to be responsible for all the energy transfer processes within the singly- and doubly-doped lanthanide ions scenarios. Temperature dependent photoluminescence spectra suggested the excellent thermal stability of Na5Lu(WO4)4:9%Tm3+,5%Dy3+ phosphor, of which the luminescence intensity at 421 K and 471 K was only 13.4% and 18.63% lower than that at room temperature, respectively. Finally, Na5Lu(WO4)4:9%Tm3+,5%Dy3+ phosphor was packaged with a 365 nm near-ultraviolet LED chip, which exhibited bright blue and yellow emission bands at various bias currents. This work showed that the developed single-phase Na5Lu(WO4)4:Tm3+,Dy3+ phosphors had wide application prospects in the field of daily lighting.