An investigation about the ability to change color and the way energy is transferred of NaYMgWO6:RE3+ (RE3+ = Tm3+, Dy3+, Tm3+/Dy3+): A new type of single-phase white phosphor for WLEDs

Novel NaYMgWO6:Tm3+, Dy3+ phosphor is synthesized by solid-state reaction method in air. The phase structure was meticulously analyzed through XRD and Rietveld refinement techniques. Dy3+ doped NaYMgWO6 phosphors emitted yellowish-white light, which was observed. Surprisingly, the introduction of Tm3+ ions resulted in white-emitting, which was further studied with the aid of a spectrometer. By fixing the concentration of Tm3+ ions and subsequently adjusting the co-doping concentration of Dy3+ ions or altering the excitation wavelength, the CIE coordinates of NaYMgWO6:Dy3+, Tm3+ phosphors shifted from the blue-violet region to the yellowish-white region. In particular, when b = 0.2 mol, there was efficient energy transfer from Tm3+ to Dy3+, with an energy transfer efficiency of 95.1%. The gradual decrease of the lifetime at 454 nm monitoring implies that there is indeed an energy transfer process from Tm3+ to Dy3+ and that the probability of energy transfer from Tm3+ to Dy3+ gradually increases with increasing Dy3+ concentration. These findings indicate that NaYMgWO6: aTm3+, bDy3+ phosphors offer a novel approach to researching single-phase white phosphors.