Effect of co-doped metal caions on the properties of Y₂O₃:Eu³⁺ phosphors synthesized by gel-combustion method

Y₂O₃:Eu³⁺ phosphors co-doped with different metal cations (Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺) are prepared by the gel-combustion method with Y₂O₃, Eu₂O₃, and R(NO₃)_x (R=Li, Na, K, Mg, Ca) serving as raw materials and glycine as fuel, calcined at 1000 ℃ for 2 h. The synthesized Y₂O₃:Eu³⁺ phosphors doped with different metal cations and doping ratios are characterized by x-ray diffractometry (XRD), fluorescence and phosphorescent spectrophotometer. The co-doping metal cations are advantageous to the development of Y₂O₃:Eu³⁺ lattice. All the samples can emit red light peaked at 611 nm under 254-nm excited. The luminescence intensities of co-doping samples are increased because the cations increase the electron transition probability of Eu³⁺ from ⁵D₀ level to ⁷F level. The fluorescence lifetime of Eu³⁺ (⁵D₀→⁷F₂) is increased by doping metal cations.