White-emitting phosphors Ca6La2Na2(PO4)6F2:Dy3+ and luminescence enhancement through Ce3+ → Dy3+ energy transfer

Ce3+ and Dy3+ activated fluoro-apatite Ca6La2Na2(PO4)6F2 with chemical formulas Ca6La2−xLnxNa2(PO4)6F2 (Ln = Ce3+, Dy3+) were prepared by a solid state reaction technique at high temperature. The vacuum-ultraviolet (VUV) and ultraviolet (UV) spectroscopic properties are investigated. The results indicate that Ce3+ ions show the lowest 5d excitation band at ∼305 nm and a broad emission band centered at ∼345 nm. Dy3+ ions exhibit intense absorption at VUV and UV range. White-emitting under 172 nm excitation is obtained based on two dominant emissions from Dy3+ ions centered at 480 and 577 nm. In addition, the energy transfer from Ce3+ to Dy3+ in the co-doped samples are observed and discussed.