| Summary: | 碩士 === 國立臺北科技大學 === 材料科學與工程研究所 === 95 === The europium（III）tungstate and europium（III）molybdate were prepared by solid state reaction method and their photoluminescent（PL）properties were investigated. The effects of Eu3+ concentration and calcination temperature were both on the luminescence behavior of the solid solutions are examined.
The characteristics of Eu2-xYx(MoO4)3 phosphors were found to depend on the amount of europium ions used. The highest integrated emission intensity is offered by Eu1.6Y0.4(MoO4)3，fired at 500oC for 4 h and 700 oC for 6 h. The emission ratio of (5D0 → 7F2 / 5D0 → 7F1) reveal that the site symmetry of Eu3+ ions decreases with increasing doping concentration. According to the X-Ray Diffraction (XRD) data, we didn’t find the direct relationship between the emission intensity and the phase or the crystallinity, because the phosphors were only changed the structure but maintained the MoO42-.
The characteristics of Eu2-xYxW2O9 phosphors were found to depend on the amounts of yttrium ions and calcination temperature. The highest integrated emission intensity is offered by Eu1.4Y0.6W2O9, fired at 1200oC for 2 h. When the amount of yttrium were below 30 mol%, the addition of yttrium were decreased the concentration quenching effect caused by europium. When the amount of yttrium were above 40 mol%, the second phase, Y2W3O12, were caused the quenching of the emission intensity. According to the XRD data, the emission intensity were increased with an increase of the crystallinity of Eu2W3O12.
The europium（III）was used as activator in both of molybdate and tungstate phosphor, which have the similar luminescence properties. Due to 5D0 → 7F2 electric dipole transition ,the phosphors emitted bright red luminescence centered at 614nm, indicating that the europium（III）didn’t occupy the site which is possessing inverse symmetry. They are excellent red emitting LED phosphor due to its best excitation band .Nearing UV range ~ 400nm is being emitting by InGaN chip.
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