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Ion co-doped fluorescent effect of rare earth doped nanocrystals

Author: LeiZuo
Tutor: ZhengHaiRong
School: Shaanxi Normal University
Course: Optics
Keywords: Eu3 / Tm3 / Pr3: LaF3/LaOF nanocrystals Fluorescence emission Fluorescence enhancement Symmetry
CLC: TB383.1
Type: Master's thesis
Year: 2010
Downloads: 65
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Abstract


The rare earth doped nanocrystals is the recent development of a new type of light-emitting materials. It also has the common advantages of nano-materials and rare earth ions occupy a pivotal position in the light-emitting materials. This thesis Hydrothermal Synthesis of Eu3 / Tm3: LaF3/LaOF nanocrystals and Eu3, Pr3 single blending co-doped the LaF3 and LaOF nanocrystals; application of laser spectroscopy to study the doping LaF3/LaOF nanocrystal fluorescence emission nature, the analysis of the matrix properties of the nanocrystals, the impact of the local environment of the dopant ions, as well as the nature of the dopant ions and the energy level structure factors of the nature of the fluorescence emission. The main content is divided into the following three parts: the first part describes the hydrothermal method based on the use of water and heat - the sintering process of the tetragonal structure Eu3 of Tm3 single blending codoped LaOF of LaF3 nanocrystals and of Eu3 Pr3 co-doped single blending LaOF, LaF3 nanocrystals. The second part of the study, Eu3 + fluorescence enhancement effect due to the ion codoped triggered by the local environment and the symmetry of the change, and the resulting co-doped Tm3 ion in fluoride nanocrystals. The third part the doping level structure of the ion nature and symmetry of nano-crystal matrix changes and other factors, the fluorescence emission properties of doped with rare earth ions in the matrix changes and ion codoped. Part I: the tetragonal structure LaOF: of Eu3 / Tm3; LaOF: Eu3; LaOF: of Tm3; LaOF: Pr3; LaOF: Applied Hydrothermal Synthesis and Characterization of Eu3 / Pr3 nano of crystal water hot - sintering method - sintering method synthesized having a tetragonal structure LaOF: Ln3 nano crystals. Compared synthesis techniques with conventional tetragonal structure LaOF nanocrystals, the method having a production process is simple, the preparation conditions low requirement advantages. The tetragonal structure LaOF: Eu3 / Tm3 nm crystals When the Eu3 the concentration of 1.0 mol%, found that the strongest of the red fluorescent emission corresponding to the co-doped the Tm3 the optimum doping concentration of 0.5m0l%. Part II: doping ion local environment and symmetry changes LaOF: Eu3 / fluorescence emission properties of Tm3 nanocrystals of Eu3 laser spectroscopy method the tetragonal structure LaOF: of Eu3 and LaOF: Eu3 / Tm3 Eu3 fluorescence emission. 532 nm continuous and pulsed laser excitation, observed the fluorescence radiation stems from of Eu3 the 5D1 and 5D0 two excited states. Wherein co-doped nanocrystals of Eu3 5D0 → 7F2 the forced electric dipole radiation corresponding to the transition of the red fluorescent emission intensity is significantly higher than the single doped nanocrystal the Eu3 corresponding fluorescence emission intensity, the reason is due to the incorporation of Tm3 substituted Eu3 and of La3 LaOF portion so the Eu3 ions nearest neighbor bond length in certain direction is changed due to the incorporation of the Tm3; while the interaction between ions by La3 and Eu3 becomes of La3, Eu3 ff transition between Tm3 and the role of these changes are to a certain extent increase Eu3 the local environment of the asymmetry of the Eu3 ion forbidden is further lifted, thereby Eu3 radiation intensity of the red fluorescent be greatly enhanced. Part III: the matrix structure, and the excitation light wavelength change LaF3/LaOF: LN3 (Ln3 = of Eu3 fluorescent emission of the change of the matrix structure, the Pr3 *, TM3) for the rare earth doped emitting ions in different local environments, thereby conditions change and the impact of doping ion fluorescence emission properties. The part of the laser spectroscopy method, in 532nm, 442 nm and 355 nm laser excitation matrix structure changes fluoride nanocrystals doped with rare earth Eu3, Pr3 and the Tm3 the fluorescence emission characteristics were investigated as well as The same matrix orders blending co-doped rare earth ion fluorescence emission characteristics. Basis the doping level structure of the ion nature and symmetry of nano-crystal matrix changes and other factors, the observed phenomena to explore the combination of the matrix structure changes and ion doping coexisting ions The fluorescence emission characteristic. The results showed: when the Pr3 and Tm3 respectively co-doped with Eu3 red fluorescence radiation intensity and color purity improvement.

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