Dissertation
Dissertation > Industrial Technology > Chemical Industry > Reagents and the production of pure chemicals > Photochemical substances

Study on the Photoluminescence Properties of the Rare Earth Doped Oxide Phosphors Prepared by Hydrothermal Method

Author ShiLingYun
Tutor YaoKuiHong;WangLongCheng
School Zhejiang University of Technology
Course Materials Processing Engineering
Keywords Phosphors Rare earth oxide Photoluminescence Metals ions Co-doping
CLC TQ422
Type Master's thesis
Year 2011
Downloads 92
Quotes 1
Download Dissertation

Due to the potential applications in the tricolor energy-saving lamps, cathode ray tube, field emission display and plasma display panel and so on, phosphors based on the rare earth elements (RE) doped materials have attracted enormous interests. However, the mainly used phosphors are the photoluminescence material based on the sulfide. Sulfide based phosphors have many disadvantages such as: poor thermal stability and generation of contamination gas. Even though the RE based phosphors have good photoluminescence properties, the cost is too high. Therefore, it is of great importance to reduce the environment pollution and lower the cost as well as to improve the photoluminescence properties of RE based phosphors.In the thesis, a novel synthesis route of Y2O3:Eu3+, Gd2O3:Eu3+ and Y2O3:Tb3+, Gd2O3:Tb3+ phosphor was proposed. By adjusting the experimental conditions, the optimum doping amount of activator ions (Eu3+ and Tb3+) was achieved. Furthermore, metals ions (Li+, Mg2+, Al3+) were co-doped into the phosphors to improve the photoluminescence properties of the as-prepared phosphors, make sure which the best doping ions and theirs the best doping amounts. The major results achieved in the thesis are given as follows:Firstly, red phosphors Y2O3:Eu3+and Gd2O3:Eu3+ were prepared by a simple hydrothermal process followed by a post-annealing process. Y2O3:Eu3+ phosphor achieves the strongest emission intensity as the molar ratio of Y3+ to Eu3+ is 20:1. Gd2O3:Eu3+ phosphor achieves the strongest emission intensity as the molar ratio of Gd3+ to Eu3+ is 30:1. In order to further enhance the emission intensity, metals ions (Li+, Mg2+, Al3+) were doped and red phosphors Y2O3:Eu3+:M (M=Li+, Mg2+, Al3+) and Gd2O3:Eu3+:M (M=Li+, Mg2+, Al3+) were prepared. The result showed that red phosphor Y2O3:Eu3+:Li+ achieves the strongest emission intensity as the molar ratio of Y3+:Eu3+:Li+ is 20:1:1, and the emission intensity is 1.06 times as high as that of the Y2O3:Eu3+ phosphor. Gd2O3:Eu3+:Li+ achieves the strongest emission intensity as the molar ratio of Gd3+:Eu3+:Li+ is 30:1:0.5, and the emission intensity is 2.42 times as high as that of the Gd2O3:Eu3+ phosphor. Gd2O3:Eu3+:Mg2+ achieves the strongest emission intensity as the molar ratio of Gd3+:Eu3+:Mg2+ is 30:1:1, and the emission intensity is 1.27 times as high as that of the Gd2O3:Eu3+ phosphor. For the phosphors doped with Al3+, the emission intensity of Y2O3:Eu3+ and Gd2O3:Eu3+ decreased. The result shows that Li+ ions are suitable dopants for the improvement of photoluminescence properties of Y2O3:Eu3+, while Li+ and Mg2+ ions are suitable dopants for the improvement of photoluminescence properties of Gd2O3:Eu3+.Secondly, green phosphors Y2O3:Tb3+and Gd2O3:Tb3+ were prepared by a simple hydrothermal process followed by a post-annealing process. Y2O3:Tb3+ phosphor achieves the strongest emission intensity as the molar ratio of Y3+ to Tb3+ is 20:1. Gd2O3:Tb3+ phosphor achieves the strongest emission intensity as the molar ratio of Gd3+ to Tb3+ is 30:1. In order to further enhance the emission intensity, metals ions (Li+, Mg2+, Al3+) were doped and green phosphors Y2O3:Tb3+:M (M=Li+, Mg2+, Al3+) and Gd2O3:Tb3+:M (M=Li+, Mg2+, Al3+) were prepared. The result showed that green phosphor Y2O3:Tb3+:Li+ achieves the strongest emission intensity as the molar ratio of Y3+:Tb3+:Li+ is 20:1:1, and the emission intensity is 1.16 times as high as that of the Y2O3:Tb3+ phosphor. Y2O3:Tb3+:Mg2+ achieves the strongest emission intensity as the molar ratio of Y3+:Tb3+:Mg2+ is 20:1:10, and emission intensity is 1.04 times as high as that of the Y2O3:Tb3+ phosphor. Gd2O3:Tb3+:Li+ achieves the strongest emission intensity as the molar ratio of Gd3+:Tb3+:Li+ is 30:1:1, and the emission intensity is 1.51 times as high as that of the Gd2O3:Tb3+ phosphor. Gd2O3:Tb3+:Mg2+ achieves the strongest emission intensity as molar ratio of Gd3+:Tb3+:Mg2+ is 30:1:5, and the emission intensity is 1.11 times as high as that of the Gd2O3:Tb3+ phosphor. For the phosphors doped with Al3+, the emission intensity of Y2O3:Tb3+ and Gd2O3:Tb3+ decreased. The result shows that Li+ and Mg2+ ions are suitable dopants for the improvement of photoluminescence properties of Y2O3:Tb3+ and Gd2O3:Tb3+.Thirdly, red phosphors Y2O3:Eu3+:M (M=Li+, Mg2+, Al3+) and Gd2O3:Eu3+:M (M=Li+, Mg2+, Al3+) and green phosphors Y2O3:Tb3+:M (M=Li+, Mg2+, Al3+) and Gd2O3:Tb3+:M (M=Li+, Mg2+, Al3+) were prepared by a hydrothermal process. The results of XRD showed that all prepared phosphors with a cubic crystal structure. Different doping ions or same doping ions with different doping amounts have great effect on the structural properties of the as-prepared phosphors.In conclusion, phosphors Y2O3:Eu3+and Gd2O3:Tb3+ were prepared by hydrothermal method. It is found that the doping metals ions (Li+, Mg2+, Al3+) may improve the photoluminescence properties and the thermal stability. Finally, the result shows that phosphors: Li+ doped red phosphors Y2O3:Eu3+ and Gd2O3:Eu3+, Mg2+ doped red phosphors Gd2O3:Eu3+; Li+ and Mg2+ doped Y2O3:Tb3+ and Gd2O3:Tb3+ show better photoluminescence properties.

Related Dissertations
More Dissertations