The Study Of The Rare Earth Luminescent Materials

Now the rare earth elements are one of the most important parts in the new photoelectromagnetism materials. The rare earth luminescent materials, especially rare earth trichromatic phosphors, are used widely. In this dissertation, we mainly discussed the preparation and characteristics of the rare earth green phosphates and the red phosphors (Y2O3:Eu). It is greatly useful for the industrial production. The experiments can be summarized as follows.(1) The rare earth nanophophors can meet the challenging demand for new functional devices but their luminescence is always poor. Here we report a simple method to prepare uniform (La, Ce, Tb)PO4sphere-like nano aggregates from the precipitated nano phosphor crystallites without using any additive. The spontaneous aggregation is only induced and controlled by the suspension pH conditions. It is found that the100nm spherical aggregates can significantly improve the green emissions of the (La, Ce, Tb)PO4nanoparticles. The intensity of the aggregates can be about10times as that of the80nm-sized individual ones. This study may provide a useful but convenient strategy in the improvement and application of nanophosphors.(2) To meet the need of the market, we did some working in the rare earth green phosphates and synthesized by high-fired reaction. LAP is superior to CAT, because of the outstanding stability and luminescence efficiency. In addition, luminous flux of LAP is high in fluorescent lamps. There is a big application market for LAP and it is also necessary to do more studies and explorations.(3) Quantum cutting could be theoretically obtained for Eu3+-doped Gd compounds, because the Gd3+excitation of6GJ—6PJ and the Eu3+excitation of7FJ—5Do are well overlapping. And it is helpful for improving the luminescence efficiency and the brightness of phosphors when quantum cutting happen. So we prepared Eu3+Gd3+codoped Y2O3red phosphors by high-temperature solid state reaction and discussed their characteristics such as the brightness, granularity, spectrum and luminous flux.