| The luminescent mechanism, applications and problems in application of rare earth complexes were summarized in the paper. The methods that rare earth complexes were doped in SiO2by sol-gel method were raised to resolve the problems of poor thermal and optical stability of rare earth complexes. The effects of SiO2 organically modified by silane coupling agent and PEG on the performance of material were researched.Eu(BA)3phen/SiO2 was synthesized by three different sol-gel methods and it has best luminescent performance by two-step-method. The optimal parameters of two-step-method were : the R was 4 ,the molar ratio of TEOS:HCl:(CH2)6N4 was 1:7.5×10-4:5×10-3, the precursor solution converted to wet gel at 40℃. Compared with Eu(BA)3 luminescent powder, Eu(BA)3/SiO2 synthesized at this condition had a narrower maximal excitation peak and a small blue shift , from 288nm to 280nm in excitation spectra. The 5D0→7F1 and 5D0→7F2 transition peak of the Eu3+ion appear at 594nm and 618nm in emission spectra and its emission intensity was three times as intensity as powder. The material was characterized by date thermal analysis and thermogravimetric analysis. The results were: thermal stability of Eu(BA)3 was enhanced when it was doped in SiO2, from 435℃ to 488℃.The effects of SiO2 organically modified by silane coupling agent and PEG on luminescence of material were researched. The results were: the material modified by silane coupling agent, its emission intensity hadn't increase and even decreased, the material modified by PEG, its emission intensity increased largely. The reason was that PEG doped in SiO2 gel prevented the quenching of the OH group to the emission of the Eu3+ ion and it was proved by IR spectra of PEG-SiO2.The material was characterized using by XRD and AFM. The results were: the material was non-crystal and monolithic material and PEG was separated well in SiO2. |
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