【作者】 邬洋；

【导师】 王永生；

【作者基本信息】 北京交通大学 ， 光学工程， 2011， 博士

【摘要】 近年来,随着纳米稀土复合发光材料的迅速发展,核-壳发光材料已经成为当前荧光材料研究的重点。通过精确控制实验反应条件,可以根据需求制备一些特定形貌、大小和功能的核-壳结构发光材料。这种核-壳结构发光材料在保留了原有荧光材料的发光性质之外,还增加了形状规则,单分散性高,各发光中心相互独立等独特性质,可作为新型稀土发光和功能材料。本论文主要围绕以硅酸盐为基质的掺杂稀土发光材料展开,制备了核-壳结构SiO2@Zn2SiO4:Eu3+和SiO2@Sr2SiO4:Eu3+,Dy3+硅酸盐荧光材料,研究了核-壳结构硅酸盐材料包覆机理、制备工艺、微观结构和发光特性,主要内容包括以下几个方面：(1)调控Zn2Si04:Eu3+颗粒的形貌及尺寸。在硅源TEOS和醋酸锌为定量的情况下,水热反应(200℃)制备了不同形貌的Zn2Si04:Eu3+颗粒(球形颗粒粒径大小不一,平均直径约为200nm)。研究并改善反应条件(加入适量的表面活性剂正庚烷和油酸钠),获得了球形、尺寸更小的Zn2Si04:Eu3+和少量ZnO杂质。在此基础上,研究了反应物中水的量对杂质ZnO生成量的影响。(2)确定样品SiO2@Zn2SiO4:Eu3+中Eu3+的猝灭浓度。采用溶胶-凝胶法研究制备了包覆均匀、壳层光滑和厚度可控的核-壳结构SiO2@Zn2SiO4:Eu3+复合微球。建立了核-壳结构SiO2@Zn2SiO4:Eu3+复合微球的荧光寿命与猝灭浓度关系模型(荧光寿命快慢组分模型),并利用此模型对样品中Eu3+的猝灭浓度进行了详尽的分析。(3)建立理论模型。建立了核-壳结构SiO2@Zn2SiO4:Eu3+复合微球的光致发光(PL)发光强度与包覆层数和SiO2的半径的关系模型,分别讨论了包覆层数和SiO2的半径对样品的PL发光强度的影响。(4)调控SiO2@Sr2SiO4:Eu3+,Dy3+核-壳结构荧光微球的色温。实验结果表明,在紫外光激发下,核-壳结构荧光微球SiO2@Sr2SiO4:Dy3+发射出蓝光和黄光,且改变Dy3+浓度不足以影响到样品SiO2@Sr2SiO4:Dy3+的色坐标。在此基础上,我们引入Eu3+来调节核-壳结构荧光粉的色坐标和改变色温。(5)调控PL发光强度。研究了退火温度和电荷补偿剂对SiO2@Zn2SiO4:Eu3+和SiO2@Sr2SiO4:Eu3+,Dy3+核-壳结构荧光微球PL发光强度的影响。更多还原

【Abstract】 With the rapid development of rare earth nano-composites, the core-shell structure of rare earth nano-materials has become the study focus of the fluorescent material in recent years. By precise control of experimental conditions, people can synthesis core-shell luminescent and functional materials with special morphology and size according to specific needs. These core-shell luminescent materials not only retain the luminescent properties of original fluorescent materials, but also own spherical shape morphology and independent luminescent centers. In short, the core-shell luminescent materials can be used as a kind of fluorescent and functional material. Therefore, in this paper, the core-shell structure of silicate luminescent materials SiO2@Zn2SiO4:Eu3+and SiO2@Sr2SiO4:Eu3+,Dy3+ had been prepared by sol-gel method. In addition, the coating mechanism, preparation, microstructure, and optical properties of the core-shell structure of the silicate luminescent materials had been studied deeply and systematically.The main contents in this paper are as follows:(1)Regulate and control the morphology and size of Zn2SiO4:Eu3+ particles. With changing the reactant concentration of ammonia, different morphology and size of Zn2SiO4:Eu3+ particles had been prepared by hydrothermal method, in which TEOS was used as silicon source. Furthermore, the reaction conditions were studied and improved by adding an appropriate amount of surfactant (sodium oleate and n-heptane). Finally, the spherical and smaller Zn2SiO4:Eu3+ particles were obtained with a small amount of ZnO impurities in samples. On the basis of this work, the effects of the amount of water on the formation of ZnO impurities were discussed in detail.(2)Determine quenching concentration of Eu3+. The SiO2@Zn2SiO4:Eu3+ core-shell phosphors with uniform coating, smooth shell and controllable thickness were prepared by sol-gel method. Otherwise, the fluorescence lifetime model comprising of fast and slow components was built, which is used to analysis and determine the quenching concentration of Eu3+.(3)Build theoretical models of relationship between the photoluminescence (PL) emission intensities of SiO2@Zn2SiO4:Eu3+, coated layers (N) and particle size (D). According to these models, the effects of coated layers and particle size on the PL intensities were discussed, respectively.(4) Regulate and control the color temperature of SiO2@Sr2SiO4:Eu3+,Dy3+ particles. The results show that the SiO2@Sr2SiO4:Dy3+phosphors emit blue and yellow light under the near ultraviolet (UV) light (386nm) excitation, and the CIE chromaticity coordinate (x, y) cannot be changed by increasing Dy3+ content. On this basis, the CIE chromaticity coordinates (x, y) and color temperatures can be adjusted by introducing Eu3+.(5)Regulate and control the PL emission intensities. The effects of annealing temperature (T) and charge compensation (Li+) on the PL intensities of SiO2@Zn2SiO4:Eu3+and SiO2@Sr2SiO4:Eu3+,Dy3+particles were studied, respectively.更多还原