Crystal structure and luminescence properties of a single-component white-light-emitting phosphor Ca8ZnLa(PO4)7: Eu2+, Mn2+.

A series of novel green emission Whitlockite-type Ca8ZnLa(PO4)7:Eu2+ and color tunable Ca8ZnLa(PO4)7:Eu2+,Mn2+ phosphors were prepared by the solid-state reaction method in a reducing atmosphere. Its crystal structure and phase composition were identified by high-resolution transmission electron microscopy, selected area electronic diffraction, X-ray photoelectron spectroscopy, and X-ray powder diffraction Rietveld refinement, and it was found to be trigonal, belonging to R-3 c(161) space group. The luminescence properties of Eu2+ singly doped and Eu2+/Mn2+ codoped Ca8ZnLa(PO4)7 phosphors were revealed in detail. Ca8ZnLa(PO4)7:Eu2+ is excitable over a broad range from 200 to 450 nm with a prominent green emitting. With varied Eu2+/Mn2+ ratios, fine-tune emission under 365 nm excitation can be achieved from green (0.221, 0.468) to magenta (0.391, 0.276), especially the warm white light (0.392, 0.352), and CCT 3500 K can be obtained by the process of energy transfer between Eu2+ and Mn2+. The ET mechanism in this system is managed via the dipole-dipole interaction with the maximum energy-transfer efficiency 82.8% based on the decay lifetime data. These results suggest that as-prepared phosphors can serve as promising candidates of UV-pumped w- LEDs. [ABSTRACT FROM AUTHOR]