Single-phase white-emitting and tunable color phosphor Na3Sc2(PO4)3:Eu2+,Dy3+: Synthesis, luminescence and energy transfer

A series of Eu2+/Dy3+ single doped and co-doped Na3Sc2(PO4)(3) phosphors were synthesized by the high temperature solid-state method, and their phase, morphology, and luminescence properties were characterized. Under the excitation of 370 nm, the Na3Sc2(PO4)(3):Eu2+,Dy3+ phosphor can emit white light whose spectrum is composed of a broad emission band centered at 460 nm and the other three peaks at 483, 577, and 672 nm, respectively. There is energy transfer from Eu2+ to Dy3+ ion in Na3Sc2(PO4)(3):Eu2+,Dy3+ phosphor due to the good overlap between the emission spectrum of Na3Sc2(PO4)(3):Eu2+ and the excitation spectrum of Na3Sc2(PO4)(3):Dy3+, which is further confirmed by the fluorescence lifetime decrease of Eu2+ ion with the increase of Dy3+ concentration. The process of energy transfer is via dipole-quadruple interaction which is confirmed by applying Dexter's theory. By increasing the Dy3+ concentration, the color coordinates of the the Na3Sc2(PO4)3:0.01Eu(2+),xDy(3+) phosphors can be adjusted from blue to white, and then to yellow. The optimized concentration of Dy3+ ions is 4.0 mol%, beyond which the concentration quenching will take place. The Na3Sc2(PO4)(3):Eu2+,Dy3+ phosphor shows fairly good resistance to thermal quenching behavior, of which the emission intensity at 423 K can maintain 90.3% of the initial value (298 K). These results suggest that the Na3Sc2(PO4)(3):0.01Eu(2+),xDy(3+) phosphors have potential applications as the color-tunable or a singlephase white emitting phosphor in white LEDs.@ 2021 Published by Elsevier B.V. on behalf of Chinese Society of Rare Earths.