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Preparation and Luminescence Properties of Rare Earth Ions Eu, Tb Doped the Unitary or Binary System of SiO2 and TiO2 Nano-materials

Author: QiXia
Tutor: WangXiGui
School: Inner Mongolia Normal
Course: Inorganic Chemistry
Keywords: Monodisperse SiO2 nanoparticles Nano - SiO2-TiO2 particles Stober sol - gel method Sol - gel method . Luminescence properties Rare earth Tb3, Eu3
CLC: TB383.1
Type: Master's thesis
Year: 2010
Downloads: 118
Quote: 0
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Abstract


This thesis Stober sol - gel method of rare earth the of Eu 3 (Tb 3 ) doped nano-silica luminous material. TEM tests through the sample, the sample is a nano-spherical particles with a certain monodisperse. FT-IR, XRD tests show that the samples were annealed amorphous rare earth the of Eu 3 (Tb 3 ) doping does not change SiO < / sub> mesh structure. The sample PL spectra nanomaterials prepared luminous efficiency luminous efficiency is less than the material, but in the nano-materials, quenching concentration of the rare earth ion doped been greatly improved. The papers also prepared rare earth the of Eu 3 doped nano-composite oxide TiO 2 -SiO 2 light-emitting materials. The FT-IR of the sample analysis by TiO 2 , SiO 2 between the occurrence of a role, forming a Ti-O-Si bond; sample TGA-DTA, XRD , SAED fully proved this point: when the titanium silicon molar low TiO 2 is highly fragmented in the free amorphous SiO 2 ; When titanium silicon molar ratio when Si 4 entering of TiO 2 lattice replaced part of Ti 4 location, thereby forming a Ti-O-Si structure, Eu 3 radius (0.113nm) than Ti 4 radius (0.068nm) large, so Eu 3 can not be easily replaced Ti 4 position, but evenly dispersed in the TiO 2 nanocrystalline TiO 2 crystal interface formation of Ti-O-Eu bond. In addition, the sample annealing temperature in the acid-catalyzed 300 9 00 ° C range (base-catalyzed samples annealed to 800 ℃), XRD sample remains anatase phase, indicating that the Ti- formation of O-Si bond is conducive to stability samples anatase base catalyzed samples did not stabilize the anatase phase of the sample under acid catalysis, the crystallinity is also not perfect, the acidic conditions more conducive anatase formation. Sample SEM, TEM shows that the sample particle size distribution was prepared by the two methods are more uniform, morphology, homogeneity, showing certain monodisperse spherical nanoparticles. The excitation spectra, emission spectra of the samples: ① The nano-titanium dioxide TiO 2 469nm so capable of producing oxygen vacancy emission peak at 465 nm Eu 3 ions 7F0 → 5D2 absorption transition with a large overlap, the energy transfer, such that the excitation wavelength by the ultraviolet region extended to the visible region; ② when the moles of titanium silicon relatively high Si 4 into the TiO 2 of the lattice, a substituted a portion of the position Ti 4 , electron traps of the structure can be formed, and this structure is conducive to the transfer of energy in the matrix, Eu 3 5D0 → 7F2 electric dipole transition intensity is greatly enhanced the composite oxide the Eu 3 of the luminous intensity higher than that in the pure titania strength; ③ acid catalyzed the luminous intensity of the samples under more alkaline catalyzed the luminous intensity of the sample has been significantly enhanced, rare earth Eu 3 doping concentration boundaries has also been improved, anatase phase structure of the sample than rutile phase is more conducive to the sample matrix absorbs energy and be able to absorb the energy efficiently transmitted to the light emitting center; ④ Since the nano-particles in the surface and interface effects resulting resonance energy transfer by nanoparticles boundary hinder reduced excitation from the luminescent center is transmitted to the probability of quenching center, while between the transmission frequency of the light-emitting center is greatly increased, so the samples prepared in the concentration of rare earth ions doped boundaries than bulk materials have been improved, and the emission intensity is significantly enhanced. In summary, these properties of the nano-emitting material is expected to become a potential application of the light emitting material.

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