Synthesis and optical properties of novel apatite-type NaCa3Bi(PO4)3F:Dy3+ yellow-emitting fluorophosphate phosphors for white LEDs

In this study, novel yellow-emitting fluorophosphate NaCa3Bi(PO4)3F phosphors doped with different concentrations of Dy3+ ions were first obtained via high-temperature solid-state reaction. The crystal structure, phase purity, particle morphology, photoluminescence (PL) properties, thermal stability, and luminescence decay curves of the resulting phosphors were then characterized in detail. Under the excitation of 349 nm, the three dominant peaks of the NaCa3Bi(PO4)3F:Dy3+ are centered at 480 nm (4F9/2-6H15/2), 577 nm (4F9/2-6H13/2), and 662 nm (4F9/2-6H11/2). The optimal doping concentration of Dy3+ ions in the NaCa3Bi(PO4)3F:xDy3+ phosphors is x = 5 mol%. The phosphors show excellent thermal stability with high activation energy (Ea = 0.32 eV). Eventually, the synthesized white light-emitting diode (w-LED) demonstrates the Commission International de L'Eclairage (CIE) chromaticity coordinates of (0.341, 0.334), a good correlated color temperature (CCT) of 5083 K, and a high color rendering index (Ra) of 92. Revealing its potential as yellow-emitting phosphors, the feasibility of the fabricated apatite-type NaCa3Bi(PO4)3F:Dy3+ fluorophosphate phosphors was confirmed for w-LEDs.