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 Na3Sc2(PO4)3∶0.01Eu2+,xDy3+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∶0.01Eu2+,xDy3+phosphors have potential applications as the color-tunable or a single-phase white emitting phosphor in white LEDs.