Luminescent properties of Dy³⁺ and/or Eu³⁺ doped Mg₂Al₄Si₅O₁₈ phosphors and energy transfer between Dy³⁺/Eu³⁺ ion pairs

A series of Dy³⁺ and/or Eu³⁺ doped Mg₂Al₄Si₅O₁₈ phosphors were synthesized by a solid state reaction. The phase, microstructure and luminescent properties of the phosphors were investigated. The XRD patterns and SEM images show that the doping ions have no influence on the phase and microstructure of the phosphors. The Dy³⁺ or Eu³⁺ singly doped Mg₂Al₄Si₅O₁₈ phosphors respectively show emission bands of Dy³⁺ or Eu³⁺ ions. Based on the overlap between the emission spectrum of Mg₂Al₄Si₅O₁₈:Dy³⁺ with the excitation spectrum of Mg₂Al₄Si₅O₁₈:Eu³⁺, we speculated the possible energy transfer from Dy³⁺ to Eu³⁺ in Mg₂Al₄Si₅O₁₈:Dy³⁺/Eu³⁺ phosphors, which is confirmed by the decreases of Dy³⁺ emission intensity with the increasing Eu³⁺ concentrations. The decreases of decay time of Dy³⁺ emission gave the further evidence to the energy transfer from Dy³⁺ to Eu³⁺. The energy transfer efficiency increases from 7.35% to 62.41% when the codoped Eu³⁺ concentration increases from 1 mol% to 6 mol%.