Synthesis and optical properties of novel apatite-type NaCa_(3)Bi(PO_(4))_(3)F:Dy^(3+)yellow-emitting fluorophosphate phosphors for white LEDs

In this study,novel yellow-emitting fluorophosphate NaCa_(3)Bi(PO_(4))_(3)F phosphors doped with different concentrations of Dy^(3+)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 NaCa_(3)Bi(PO_(4))_(3)F:Dy^(3+)are centered at 480 nm(^(4)F_(9/2)-^(6)H_(15/2)),577 nm(^(4)F_(9/2)-^(6)H_(13/2)),and 662 nm(^(4)F_(9/2)-^(6)H_(11/2)).The optimal doping concentration of Dy^(3+)ions in the NaCa_(3)Bi(PO_(4))_(3)F:xDy^(3+)phosphors is x=5 mol%.The phosphors show excellent thermal stability with high activation energy(Ea=0.32 eV).Eventually,the synthesized white lightemitting 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 NaCa_(3)Bi(PO_(4))_(3)F:Dy^(3+)fluorophosphate phosphors was confirmed for wLEDs.