Sol-gel synthesis and luminescent properties of a novel KBaY(MoO4)3:Dy3+ phosphor for white light emission

A novel kind of yellow KBaY(MoO₄)₃:Dy³⁺ (KBYM:Dy³⁺ for short) phosphor was prepared via sol-gel method and evaluated as a component candidate for NUV excited LED. The structure, morphology and luminescent properties of the as-synthesized phosphor were investigated by means of X-ray diffraction (XRD), Raman spectra, scanning electron microscope (SEM), excitation and emission spectra, and decay curves. The results of XRD and Raman spectra show that KBYM:Dy³⁺ phosphors can be synthesized by sol-gel method at a minimum temperature of 550 °C. The excitation spectra exhibited intense absorption bands in the NUV and blue region, which match well with the commercial LED chips. Under the excitation of 352 nm, a dominant emission was found at 575 nm corresponding to the ⁴F_9/2 → ⁶H_13/2 transition, which means that Dy³⁺ ions occupy a low symmetry site in KBYM matrix. The thermal stability of the phosphor was investigated based on the crossover model, and the activation energy was determined to be 0.235 eV. The Inokuti-Hirayama (IH) model has been applied to the analysis of the decay curves, and the results showed that the energy transfer process among Dy³⁺ ions is controlled by dipole-dipole interactions. Lastly, both yellow and white LEDs were fabricated with the as-synthesized phosphor and their luminescent performances were investigated as a function of filament currents.