Synthesis and photoluminescence enhancement of Ca9La(VO4)7:Eu3+ red phosphors by Mg2+ co-doping for white LEDs

Red-emitting phosphors of Ca 9 La(VO 4 ) 7 :Eu 3+ , Mg 2+ with different Mg 2+ concentrations were synthesized by a citric acid-fueled combustion method. The structures and photoluminescence properties of the synthesized samples were researched by powder X-ray diffraction, scanning electron microscopy, and photoluminescence (PL) spectroscopy. The effects of the sintering temperature and Mg 2+ concentration on the phase compositions, morphologies, PL properties, and fluorescent lifetimes of the obtained products were investigated. The results of XRD indicated that all of the resulting phosphors were composed of a single Ca 9 La(VO 4 ) 7 phase. The PL spectra suggested that the strongest emission peak centered at 618 nm arose from the 5 D 0 → 7 F 2 electric dipole transition of Eu 3+ and that the emission intensity changed greatly with changes in the sintering temperature. Remarkably, the emission intensity of the Ca 9 La(VO 4 ) 7 :Eu 3+ phosphor could be drastically increased by co-doping with Mg 2+ . Furthermore, the color purity of the Ca 9 La(VO 4 ) 7 :0.01Eu 3+ , 0.02Mg 2+ phosphor was higher than that of the Ca 9 La(VO 4 ) 7 :0.01Eu 3+ phosphor. The Ca 9 La(VO 4 ) 7 phosphor co-doped with Eu 3+ and Mg 2+ could be effectively excited by blue light, suggesting its potential as a red phosphor for applications in white light-emitting diodes using blue-light excitation.