Fixed Yellow-to-Blue Intensity Ratio of Dy³⁺ in KY(CO₃)₂ Host for Emission Color Tuning

Dy³⁺, Ce³⁺ co-doped KY(CO₃)₂ phosphors with a monoclinic structure were synthesized using the hydrothermal method to create a fixed yellow-to-blue ratio emission. The [YO₈] polyhedron, consisting of a Y atom and eight oxygen atoms, forms a relatively independent microstructure within the KY(CO₃)₂ host. Y³⁺ ions are partially replaced by Ce³⁺ or Dy³⁺ ions to construct the [CeO₈] or [DyO₈] polyhedral fluorescence emission unit. The spectral measurements indicate that Ce³⁺ and Dy³⁺ can maintain relatively independent fluorescence emission characteristics in the KY(CO₃)₂ host. The yellow-to-blue intensity ratio of Dy³⁺ remains close to 1 and does not change with the variation in the doping concentration of KY(CO₃)₂:Dy³⁺ and KY(CO₃)₂:Dy³⁺,Ce³⁺ phosphors. When Ce³⁺ and Dy³⁺ are co-doped with KY(CO₃)₂, the emission intensities of Dy³⁺ under 339 nm and 365 nm excitation increase by 8.43 and 2.32 times, respectively, through resonance energy transfer and cross-relaxation. All Ce³⁺-doped KY(CO₃)₂:Dy³⁺ phosphors can emit white light. Among them, the emitted light of KY(CO₃)₂:3%Dy³⁺,5%Ce³⁺ is closest to standard daylight. Therefore, a stable [YO₈] polyhedral structure can be used to achieve more color tuning of light.