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

Phosphors of KNaCa2(PO4)2:Ce3+, Dy3+ were prepared via high temperature solid-state reaction at 1000 °C. The fluorescence properties of the samples and the energy transfer from Ce3+ to Dy3+ were investigated. The fluorescence spectra shows that doped-Ce3+ as sensitizer enhances the emission intensity of Dy3+ obviously by transferring its energy to Dy3+. The characteristic emission peaks of Ce3+ (360 nm) and Dy3+ (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 Ce3+ to Dy3+ in KNaCa2(PO4)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 Ce3+ and Dy3+.

► Doped-Ce3+ as sensitizer enhances the emission intensity of Dy3+ obviously.
► Effective energy transfer from Ce3+ to Dy3+ in KNaCa2(PO4)2 was confirmed.
► The reason and mechanism of energy transfer from Ce3+ to Dy3+ were investigated in detail.
► Ce3+ and Dy3+ co-doped KNaCa2(PO4)2 can be a potential white light emitting phosphor for UV LEDs.