Tailoring narrow-band blue emitting Ca7(Mg, Zn)2P6O24: Eu2+ phosphate phosphor via crystal lattice distortion for WLEDs

Abstract Currently, the development of highly efficient emission tunable phosphor materials is necessary for improving the lighting quality of UV light based white emitting diodes (WLEDs). Herein, a series of new blue-emitting Ca7(Mg, Zn)2P6O24: Eu2+ (CM/ZP: Eu2+) phosphors were successfully synthesized through a high temperature solid phase reaction process. Interestingly, through constructing Ca7(Mg, Zn)2P6O24: Eu2+ solid solutions based on a complete substitution of Mg2+ by Zn2+, the controllable blue-shift emission from 441 to 418 nm could be realized. This result could be attributed to the selective occupation of different Ca2+ ions for Eu2+ ions due to distortion of coordination polyhedron. The corresponding full width at half maximum (FWHM) exhibits a gradual narrowing from 66 to 27 nm after [Zn→Mg] replacement, and the color purity of Eu2+ emission in Ca7Zn2P6O24 (CZP) could reach 93.2%. Finally, the thermal quenching resistance of the as-prepared Ca7(Mg, Zn)2P6O24: Eu2+ phosphors show remarkably excellent performance. Moreover, the thermal stabilities working at 150 °C of CMZP: Eu2+ were gradually improved from 71% for CZP: Eu2+ to 97% for CMP: Eu2+ of original photoluminescence intensity. Generally, the cation substation induced selective occupation of Eu2+ to control FWHM is an efficient design to achieve emission-tunable phosphors, and the developed narrow-band Ca7(Mg, Zn)2P6O24: Eu2+ blue-emitting phosphors could serve as potential blue phosphors for WLEDs application.