Synthesis and luminescent properties of a novel red emitting La2Mo3O12: Li+, Eu3+ phosphor
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La2Mo3O12: Eu3+ (5 mol%) red phosphors co-doped with different concentrations of Li+ ions have been synthesized by a citric acid based sol–gel method. X-ray powder diffraction, field emission scanning electron microscope, photoluminescence (PL) spectra and luminescence decay kinetics were used to characterize the synthesized samples. The results show that the excitation spectra of La2Mo3O12: Li+, Eu3+ phosphors consist of a broad and strong absorption band in the ultraviolet (UV) and near ultraviolet (NUV) regions, which can be efficiently excited by the NUV light. The emission spectra of the phosphors exhibit characteristic luminescence 5D0→7F J (J = 1, 2, 3, 4) of the Eu3+ ions with a dominant electronic transition located at 615 nm (5D0→7F2). Incorporation of Li+ ions in La2Mo3O12: Eu3+ lattice can induce a remarkable improvement of their PL intensity and the optimal concentration of Li+ is 15 mol%. Furthermore, the estimated chromaticity coordinate about (0.65, 0.34) is very close to the ideal red light (0.670, 0.330). These results indicate that the Li+ doped La2Mo3O12: Eu3+ phosphors can serve as NUV excited red phosphors for white light emitting diodes.
This work was supported by the grants of Specially-Appointed Professor of Jiangsu and the National Science Foundation of China under Grant Nos. 11474167 and 51502142. It is also sponsored by National Training Program for Undergraduate on Innovation of Jiangsu Province (201610300067).
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