Fabrication And Luminescence Properties Of RE₂Zr₂O₇?RE=Y,La? Nano Luminescent Materials

Rare-earth zirconate RE₂Zr₂O₇?RE=Y,La,Gd,Lu? possessing either pyrochlore structure or defect fluorite structure, is a new type of luminescent materials. With high refractive index, big effective atomic number and high thermal stability, this system has increasingly become the focus of recent investigations for fluorescent, display technology. In this work, RE₂Zr₂O₇ ?RE=Y, La? nanopowders were successfully synthesized by three different methods, and the fluorescence property of RE₂Zr₂O₇ ?RE=Y,La? nanopowders doped by three different active ions (Eu³⁺,Dy³⁺,Sm³⁺ were studied. X-ray diffraction ?XRD? and Scanning Electronic Microscope ?SEM? were used to characterize the crystal structure and morphology; Photoluminescence ?PL? studied the luminescence properties.Firstly, RE₂Zr₂O₇ powders were synthesized by high temperature solid state method. High temperature solid state method is simply handled, but with rather high reaction temperature. Solid state method relys on high temperature to motive atoms diffuse and combine the target products. During the process of experiments, ball-milling is used to mix the oxide raw materials intensively. From the analysis of XRD patterns, when calcinated at 1250?, there were some impurity peaks, when the temperature improved to 1450?, we got pure phase RE₂Zr₂O₇ powders, whose partical size was submicron.Then, for the sake of reducing the reaction temperature, we adopted wet chemistry methods to fabricate the nanopowders, including co-precipitation method and combustion method.Compared with samples prepared by conventional solid state method, the co-precipitation reaction temperature was reduced significantly. When calcinated at 800?, the XRD patterns of RE₂Zr₂O₇?RE=Y,La? were perfect with no impurity peaks and when it come to 1200?, the crystallinity was higher and the crystal size is about 100nm.Combustion method as one of the most commonly used methods, the reaction is effective, fast and can synthesize nanopowders with high homogeneity. All the reactants were dissolved in deionized water and prepared a solution with certain concentration, evaporate excess water till it turn into gel and then transport it onto a electric furnace, with the last drop of water evaporated, the reaction begins and finishes in a few seconds with some sparks or flames.The precursors were calcinated at different temperatures, it began to crystallize at 600? and the phase was pure, the size was nanometer.At last, Y₂Zt₂O₇?La₂Zr₂O₇??Y,La?2Zr₂O₇ with different ratios of Y/La nanopowders doped with Eu³⁺?Dy³⁺?Sm³⁺ were synthesized by Combustion method. And the luminescence properties of nano-RE₂Zr₂O₇ ?RE=Y,La? were studied.