Fluorescence properties and energy transfer of KNaCa2―x―y(PO4)2: xCe3+, yDy3+ phosphors under ultraviolet excitation

Abstract Phosphors of KNaCa 2 (PO 4 ) 2 :Ce 3+ , Dy 3+ were prepared via high temperature solid-state reaction at 1000 °C. The fluorescence properties of the samples and the energy transfer from Ce 3+ to Dy 3+ were investigated. The fluorescence spectra shows that doped-Ce 3+ as sensitizer enhances the emission intensity of Dy 3+ obviously by transferring its energy to Dy 3+ . The characteristic emission peaks of Ce 3+ (360 nm) and Dy 3+ (481 nm, 574 nm) exist simultaneously in the emission spectra of phosphors with considerable intensity under ultraviolet (UV) excitation (319 nm). The experimental results indicate there is an effective energy transfer from Ce 3+ to Dy 3+ in KNaCa 2 (PO 4 ) 2 host. This energy transfer behavior in the phosphors was discussed and the critical distance of the energy transfer is 2.076 nm. The varied emitted color of the phosphors from indigo to white can be achieved by tuning the concentration of Ce 3+ and Dy 3+ .