Ca19Zn2(PO4)14:Dy3+, M+ (M = Li, Na, K) white-emitting phosphors: Charge compensation effect of M+ on the photoluminescence enhancement

Abstract A series of β-Ca3(PO4)2 type single-component Ca19Zn2(PO4)14:Dy3+, M+ (M = Li, Na and K) white-emitting phosphors were synthesized via a high-temperature solid-state reaction method, where alkali metal ions (M+) co-doped as charge compensator into the Ca19Zn2(PO4)14:Dy3+ phosphor was aimed at improving the overall luminescence. The influences of synthesis temperature and the M+ introduction on both structure and luminescence property were thoroughly studied. X-ray diffraction patterns verify that the as-prepared phosphors attain the standard Ca19Zn2(PO4)14 phase without impurities. Photoluminescence peaks at 484 nm and 575 nm (originating from the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 electron transitions of Dy3+ ions) were produced for all samples with an excitation of 386 nm, which then combined to emit white light. The luminescence intensities of Ca19Zn2(PO4)14:Dy3+ were dramatically improved through co-doping with M+ into the phosphor structure. These results demonstrate the promising application prospects of Ca19Zn2(PO4)14:Dy3+, M+ white-emitting phosphors in white light-emitting diodes.