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Sol-Gel Synthesis of Nano-sized Phosphors and Their Properties

Author: ZhaoJinZuo
Tutor: YangZhiPing
School: Hebei University
Course: Optical Engineering
Keywords: Sol - gel method Fluorescent material Nanoscale
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 77
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Abstract


In this paper, the sol - gel method several common fluorescent materials by sol - gel method to explore and improved at lower temperatures to prepare a small particle size , dispersion, and particle size distribution is concentrated , similar to spherical fluorescent material . Optimum conditions for the resulting sample , and the optimum concentration of the activator of the test, analysis of a sample of the product structure , to study the morphology of the sample , the spectral characteristics of the resulting sample were tested , and its light emission mechanism was analyzed and inference. In this paper , the following key elements: (1) by the sol - gel method the nanoscale SR2 - xCexSi04 synthesis temperature of 900 ° C , much lower than the similar silicate materials prepared by solid desired temperature . The X -ray diffraction pattern showed that the resulting sample as a pure phase Sr2SiO4 crystal . The scanning electron microscope image shows that the sample particle size in the nanometer scale . Under 272 nm UV excitation , the sample emission spectrum of a broadband spectrum is asymmetric single peak , peak at 472 nm , typical blue- white light emission . Monitoring the 472 nm emission peak to obtain the excitation spectrum peak at 272 nm , 351 nm , the near-ultraviolet continuous spectrum . At the same time , Ce3 concentration the SR2 - xCexSiO4 luminous intensity . (2) by the sol - gel derived nano-scale CaWO4 phosphor, the emission peak at 420 nm , well-matched with the spectral sensitivity of the blue sensitive film . Its morphology and optical properties were characterized by X-ray diffraction , scanning electron microscopy and emission spectra . CaWO4 phosphor particles obtained by the method of nanoscale particle size distribution is concentrated . This phosphor is made of X -ray intensifying screen and compared with commercially available products like , can significantly improve the imaging quality of the photosensitive sheet of the intensifying screen . (3) by the sol - gel method the nano CA1 - xDyxWO4 of phosphor concentration of dy x value within the range of 0-0.04 . The crystal structure and morphology of the resulting samples were studied by XRD, SEM image . The emission spectrum from 420nm and 570nm band spectrum . The 420nm band spectrum from the W042 - molecules self-activated light-emitting , 570nm ribbon spectrum Dy the 4f → 4f transitions . By changing the doping concentration of Dy , the a CA1 - xDyxWO4 blue and yellow emission intensity ratio changes , and the cause of this change mechanism was discussed .

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