| SiO2 nano-meter luminescent materials with different types of doping or of different structure were prepared by the sol-gel and hydrothermal methods. The samples were characterized by Fluorescence Spectrum (PL), Fourier Transform Infrared Spectroscopy (FT-IR), Atomic Force Microscope (AFM) and Transmission Electron Microscope (TEM). And the luminous mechanism was studied in this paper.Through the research of different factors such as the molar ratio of H2O and annealing temperature to the fluorescence, phosphorescence intensity and phosphorescence lifetime of the sample, it showed that all the factors had influence on the luminous intensity of Tb3+doped SiO2 xerogels or films, and resulted a competitive mechanism. With the increasing amount of water, the luminous intensity of the samples annealed at 750℃first weakened, then enhanced and last weakened again. Through analyzing the phosphor properties of the samples, we found that the variation curves of the phosphorescence and luminescence intensity vs. the molar ratio of H2O showed the same trend. And the molar ratio of H2O also largely affects the decay time of the phosphorescence. Additionally, the optimum mole ratio of TEOS:ETOH:H2O is set as 1:4:4. The aging last one day, and the optimum annealing temperature at which the luminescent intensity of SiO2:Re3+samples are strongest existed in the extent from 650 to 800℃.SiO2:Re3+ luminescent xerogels and films doped Zn2+, Sn2+, Al3+ and other metal ions were prepared respectively by the sol-gel method, and the films were coated on the aerogel glasses or Si chips. The luminescent property of different metal ions doped SiO2:Re3+ samples with different forms were analyzed by making full use of the F-7000 fluorescence spectrometer. It was expected that the addition of metal ions can change the microcosmic environment of sample, as a result, the luminous efficiency of SiO2:Re3+, Mn+ would increase. Under the same conditions, the powder performed the strongest luminous intensity, followed by the film coated on glass as and Si substrate in turn. Due to the effect of local field increasing or energy transfer, the luminescent intensity of the metal ions doped SiO2:Re3+ samples were stronger than that of non-doped SiO2:Re3+ sample; the optimum annealing temperature also became lower; it corresponded to the different optimal concentrations of doped metal ions when the samples emitted the strongest light respectively, such as 0.4% for Zn2+, and 0.2% for Sn2+. In addition, the luminous intensity of the sample of SiO2:Tb3+, Zn2+ prepared through the hydrothermal method is weaker than that of the sample prepared by sol-gel preparation, mainly because of different formation of matrix network. In order to increase the luminous efficiency of rare earth doped SiO2 samples by changing the structure of nano-materials, two kinds of core-shell structures were introduced, including SiO2:Tb3+ coated SiO2 nano-spheres particles (Si@Si-Tb) and SiO2 coated SiO2:Tb3+ nano-spheres particles (Si-Tb@Si). Under a certain condition, the luminous intensity of core-shell structure was stronger than that of the powders, conclusively, the 0.8Si@Si-Tb-z sample reached the highest luminous intensity, which means that the production obtained from SiO2 nano-spheres with 0.8g nuclear quality scattering in the 25ml SiO2:Tb3+ solution without aging had a higher luminous efficiency. With the increasing of nuclear quality, numbers of ions also increased, leading to higher luminous intensity. However, the light began abating when the nuclear quality increased to a certain value, probably because the concentration quenching effect of the luminous ions happened. Through the analyzing the luminous property of the clarifying solution and the deposition samples after filtering, it showed that the luminous intensity of the products of the upper clarify solution are stronger than that of the precipitation no matter how much nuclear quality. |
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