Synthesis of LiEu1-xBix（MoO4）2 red phosphors by sol-gel method and their luminescent properties

The Bi3+ doped molybdate-based red-emitting phosphors, LiEu1-xBix(MoO4)2, were successfully synthesized with a sol-gel method. The prepared LiEu1-xBix(MoO4)2 phosphors exhibited pure and intense red emission at 613 nm under the excitation of near-UV 394 nm. It was discussed in detail that the influence of the synthesis conditions such as the doping concentration of Bi3+, the dose of citric acid, pH of the precursor solution and the sintering temperature on the emission intensity of the phosphors. According to the results, the optimal condition was obtained: the doping concentration of Bi3+ was 15 mol.%, molar ratio of citric acid to metal ions was 1.5:1, pH of the precursor solution was 1.0 and the sintering temperature was 800 ?C. The X-ray diffraction (XRD) patterns of the LiEu0.85Bi0.15(MoO4)2 phosphor prepared under the optimal condition indicated that the phosphor was single phase with tetragonal scheelite structure. The Commission Internationale de l’E-clairage (CIE) chromaticity coordinates of LiEu0.85Bi0.15(MoO4)2 were (x=0.655, y=0.345), which were closer to the national television stan-dard committee (NTSC) standard values (x=0.670, y=0.330) than that of a commercial red phosphor of Y2O2S:Eu3+(x=0.630, y=0.350). This LiEu0.85Bi0.15(MoO4)2 red phosphor is a promising candidate for the fabrication of white light-emitting diode (W-LED) with near-UV chips.