Enhanced luminescence of Dy³⁺/Bi³⁺ co-doped Gd₃Al₅O₁₂ phosphors by high-efficiency energy transfer

Series samples of Dy³⁺/Bi³⁺ co-doped Gd₃Al₅O₁₂ phosphors were successfully prepared by sol–gel combustion method. The phase composition, morphology and luminescence properties were investigated by X-ray diffraction, scanning electron microscope, photoluminescence, UV–Vis diffuse reflectance spectra, and fluorescent decay curves. Dy³⁺–Bi³⁺ co-doping had no significant effect on the host lattice of Gd₃Al₅O₁₂ (GAG). The quenching concentration of Dy³⁺ in Gd_3-xAl₅O₁₂:xDy³⁺ was determined to be 6.0 mol% (x = 0.06). At the optimal Dy³⁺ content of 6.0 mol%, the emission intensity of Dy³⁺ was greatly enhanced by Bi³⁺ co-doping. The incorporation of Bi³⁺ in GAG sample well improved the emission intensity of Dy³⁺ through the energy transfer from Bi³⁺ to Dy³⁺. The optimized composition was determined to be Gd_2.895Al₅O₁₂:0.06Dy³⁺, 0.045Bi³⁺. The chromaticity coordinate shifted to green edge area after co-doping Bi³⁺ in GAG:Dy³⁺ phosphors. The enhanced intensity and tuned luminous color of Dy³⁺/Bi³⁺ co-doped GAG phosphors provided a promising application in white light emitting diodes (WLEDs), scintillation and some other optical fields.