White emission enhancement of Ca_5(PO_4)_3CI:Dy~(3+) phosphor with Li~+/Eu~(3+) co-doping for white light-emitting diodes

摘要

Dysprosium doped chlorapatite, Ca~(5)(PO~(4))~(3)Cl:Dy_(3+)white-emitting phosphors were synthesized by a solid-state reaction method. The effects of synthesis temperature, Dy_(3+)doping concentration, Eu_(3+)co-doping concentration and charge compensator Li_(+)co-doping on the crystal structures and luminescence properties of Ca~(5)(PO~(4))~(3)Cl:Dy_(3+)samples were investigated. Ca~(5)(PO~(4))~(3)Cl:Dy_(3+), Eu_(3+)and Ca~(5)(PO~(4))~(3)Cl:Dy_(3+), Li_(+)phosphors with standard Ca~(5)(PO~(4))~(3)Cl structure were prepared by heating above 900 °C, and the doped Dy_(3+), Eu_(3+)/Li_(+)ions had no effect on the crystal structure. Under ultraviolet excitation at 366 nm, the emission spectra of Ca~(5)(PO~(4))~(3)Cl:Dy_(3+)phosphors exhibited two characteristic peaks of Dy_(3+)at 484 and 577 nm, which corresponding to the_(4)F~(9/2)→_(6)H~(15/2)and_(4)F~(9/2)→_(6)H~(13/2)electron transitions, respectively. Both blue and yellow emissions within a single-component host would constitute the white light. The white emission intensity of Ca~(5)(PO~(4))~(3)Cl:Dy_(3+)was enhanced markedly by Li_(+)co-doping as charge compensator. Moreover, Eu_(3+)co-doped Ca~(5)(PO~(4))~(3)Cl:Dy_(3+)phosphor showed an excellent warm white light with high chromaticity coordinates and low correlated color temperature though an additional red emission of Eu_(3+). The results indicate that these Ca~(5)(PO~(4))~(3)Cl:Dy_(3+), Eu_(3+)/Li_(+)phosphors have potential applications in the field of white light-emitting diodes as single-component white-emitting phosphors.