Rare earth luminescent materials, nano-structured SiO_2 Preparation and Properties

Title: Rare earth luminescent materials, nano-structured SiO_2 Preparation and Properties Author: Jing Pan Degree-granting units: Northwestern University Keywords: sol-gel method;; rare-earth-doped SiO_2;; emission spectra;; metal ions;; core-shell structure Summary: In this paper, the sol - gel method and hydrothermal method with different types and different structures of doped nano-Si02-emitting material by fluorescence (PL) spectra, infrared absorption spectroscopy (IR), atomic force microscopy (AFM), transmission electron microscopy (TEM ) and other modern means of analysis of samples were characterized, and its luminescence mechanism is analyzed. By studying the different water content, annealing temperature on the fluorescence intensity, luminescence intensity and phosphorescence lifetime and other properties, that either powder or film form for Tb3 +-doped SiO2-emitting materials, these factors also affect the luminescence of Tb3 + performance, and the luminous intensity of the impact of the formation rare earth magnets of a competitive mechanism. The sample annealed at 750 ℃ ​​luminous intensity, with the water content increases, the first increase and later decrease after decrease. By analyzing samples of the phosphorescence properties, that the water content of the phosphorescence and fluorescence intensity of the same trend, and luminescence decay time of significant impact. Finally, to determine TEOS, ethanol and distilled water, the optimal molar ratio of 1:4:4, aging time of the day, there is an optimal annealing at 650-800 ℃ temperature makes the sample SiO2: Re3 + light most . Using sol-gel method were prepared by Zn2 +, Sn2 + and Al3 + and other metal ions doped SiO2: Re3 + light dry gel and film, films were deposited on glass and silicon. Full use of F-7000 fluorescence spectrometer analysis of different metal ions doped SiO2: Re3 + luminescence properties of samples. By changing the rare earth ion doped metal ions makes the micro-environment samples SiO2: Re3 +, Mn + luminous efficiency increases. Under the same conditions, the most luminous powder, glass-plated luminous intensity of the film, followed by plating on silicon thin-film light-emitting weakest. As the local field enhancement or energy transfer effects, the metal ion-doped SiO2: Re3 +-doped sample is less strong light; metal ion-doped samples required for optimal annealing temperature than non-doped sample is reduced; different types of metal ion-doped SiO2: Re3 + samples corresponding to the strongest light the optimum concentration of different, such as when Re is the time Tb, Zn2 + doping of the best concentration of 0.4%, while the Sn2 + 0.2%. In addition, comparing the use of hydrothermal and sol-gel method has been SiO2: Tb3 +, Zn2 + luminescence properties of samples, the http://www.chinamagnets.biz/ samples found to be using the former as the latter's strong light, mainly due to the formation of the matrix network structure is different. Sol-gel method using core-shell structures were prepared SiO2: Tb3 + coated SiO2 particles (Si @ Si-Tb) and SiO2-coated SiO2: Tb3 + particles (Si-Tb @ Si) two structures, nano-materials by changing structure makes the luminous efficiency of the sample increases. Under certain conditions, core-shell structure of the luminous intensity than the Powder SiO2: Tb3 + strong, and come to 0.8 Si @ Si-Tb-z sample highest luminous efficiency, nuclear mass 0.8g of SiO2 particles dispersed in 25ml of SiO2: Tb3 + solution, the sample obtained without aging high luminous efficiency. With the nuclear mass increases, the light also increased the number of ions, luminescence enhancement, but to a certain value, the light diminished. By analyzing the clear solution obtained after filtration and precipitation of light-emitting properties of the samples and found that the supernatant from the lower precipitation than the product of luminous intensity, and has nothing to do with the nuclear mass or structure. Degree Year: 2010