Fast synthesis of Dy³⁺ and Tm³⁺ co-doped double perovskite NaLaMgWO₆: A thermally stable single-phase white-emitting phosphor for WLEDs

Single-phase double perovskite phosphor NaLaMgWO₆ was successfully synthesized via a rapid microwave irradiation method. The crystal structures of Dy³⁺ doped NaLaMgWO₆ phosphors were investigated thoroughly via X-ray diffraction and Rietveld refinement methods. The morphology was verified by transmission electron microscopy (TEM). Single-ion yellowish white light was observed in Dy³⁺ doped NaLaMgWO₆ phosphors and further luminescence quenching was investigated with the help of spectroscopy. Interestingly, we found that white light emission can be realized by the introduction of Tm³⁺ ions due to energy transfer between the doping ions. The Commission Internationale de L'Eclairage (CIE) coordinates of the NaLaMgWO₆:Dy³⁺, Tm³⁺ phosphors shift from the green region to the white region by means of a doping concentration adjustment of the lanthanide ions. Luminescent and thermal properties of the single-phase white phosphor present great potential in WLEDs.