Effects of Ta-O charge transfer band on the color-tunable emissions of Dy3+-activated SrLaMgTaO6 phosphors

The color-tunable emissions of Dy3+-activated SrLaMgTaO6 phosphors were synthesized via a conventional high temperature solid-state reaction method. The phase and the luminescent properties were well characterized by X-ray diffraction patterns (XRD), diffuse reflectance spectra, luminescent spectra and lifetime. The XRD result revealed the as-prepared samples exhibited a monoclinic structure with the space group P21/n. Moreover, the obtained phosphors could be efficiently excited by the UV (250 nm), near-UV (354 and 390 nm) and blue (452 nm) lights. A gradual enhancement of PL emission intensity was observed with elevating the Dy3+ ion concentration and reached its maximum value when the doping concentration was 7 mol%. The critical distance was estimated to be 15.13 Å. In addition, the emission color of the as-synthesized samples were changed from blue to pure white and finally to yellow by properly adjusting the excitation wavelength and the doping concentration. All the results confirmed that Dy3+-activated SrLaMgTaO6 phosphors may have potential applications in white light-emitting diodes as white light-emitting phosphors.