A novel Dy³⁺-activated single-phase white light-emitting phosphor for solid-state lighting

The radius of trivalent scandium ions is much smaller than those of other rare earth ions and thus research studies targeting the substitution of the scandium site with other light-emitting rare earth ions are rarely reported. In our present work, special attention is paid to the effect of Dy3+ doping on the crystal structure, atomic site occupancy and luminescence properties of the ScCaBO4 host as Dy3+ often serves as an individual activator for single-phase white light-emitting phosphors. Herein a series of ScCaBO4:Dy3+ phosphors were prepared by solid-state reactions. The phase composition was recorded by X-ray diffraction analysis and XRD refinement reveals that a pure phase could be maintained even when the Dy3+ concentration reaches 11%. Scanning electron microscopy (SEM) was utilized to observe the morphology and EDS mapping was used to investigate elemental distribution. The luminescence performances of the phosphors were investigated using UV-vis diffuse reflectance spectra, steady-state excitation and emission spectra and also transient luminescence decays. Dy3+ luminescence can be ascribed to its F-4(9/2) -> H-6(15/2), H-6(13/2) and H-6(11/2) transitions, producing blue, yellow and red emissions. The Dy3+ concentration was further optimized at 3%, at which the CIE coordinates and fluorescence lifetimes were (0.425, 0.413) and 0.546 ms, respectively. Thermal quenching studies of the ScCaBO4:0.03Dy(3+) phosphor show that Dy3+ luminescence at 400 K can maintain 60.91% of its initial value measured at room temperature. All the results indicate that the ScCaBO4:Dy3+ inorganic phosphors could be a promising single component phosphor for near-UV chip based WLEDs.