Synthesis and photoluminescence enhancement of Ca9La(VO4)7:Eu3+ red phosphors by Mg2+ co-doping for white LEDs
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Red-emitting phosphors of Ca9La(VO4)7:Eu3+, Mg2+ with different Mg2+ 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 Mg2+ 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 Ca9La(VO4)7 phase. The PL spectra suggested that the strongest emission peak centered at 618 nm arose from the 5D0 → 7F2 electric dipole transition of Eu3+ and that the emission intensity changed greatly with changes in the sintering temperature. Remarkably, the emission intensity of the Ca9La(VO4)7:Eu3+ phosphor could be drastically increased by co-doping with Mg2+. Furthermore, the color purity of the Ca9La(VO4)7:0.01Eu3+, 0.02Mg2+ phosphor was higher than that of the Ca9La(VO4)7:0.01Eu3+ phosphor. The Ca9La(VO4)7 phosphor co-doped with Eu3+ and Mg2+ 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.
The authors acknowledge financial support from the Key Scientific and Technological Research and Development Program (Grant No. 2017GZ0400), Sichuan Province, P.R. China.
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