Synthesis and luminescence properties of NaBaPO4:Tm3+,Dy3+ white-light emitting phosphors with enhanced brightness by Li+ co-doping

In this paper, a series of NaBaPO4:Tm3+, Dy3+, Li+ (NBPO) single-doped and co-doped phosphors were synthesized successfully by the traditional high-temperature solid state reaction method. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), photoluminescence (PL) spectra and fluorescent decay curves. The XRD results showed that samples NaBaPO4: Tm3+, Dy3+ were matched well with the standard profile NaBaPO4. White light emission can be achieved by simply adjusting the doping concentration of Tm3+ and Dy3+ ions in NaBaPO4 host. The CIE coordinates (0.3192,0.2951) of phosphor NBPO: 0.01 Tm3+, 0.04Dy(3+) was closest to the coordinates of ideal white light. The enhanced emission intensity was achieved by doping Li+ ions. When the Li+ ions doping concentration was 0.01, the emission intensity reached the maximum, which was 2.2 times the emission intensity of the non-doped Li+ phosphor. The results demonstrated the promising application of NaBaPO4: Tm3+, Dy3+, Li+ phosphor for near-UV white LEDs.