基于统计数学原理的LED氮化物荧光材料优化合成、晶体结构解析与能量传递机理研究

发布时间：2018-03-29 09:29

本文选题：白光LED(发光二极管)　切入点：荧光粉　出处：《合肥工业大学》2015年硕士论文

【摘要】：白光LED(发光二极管,Light emitting diode)灯作为第四代绿色光源以其高效、节能、环保、低成本等优点在现代社会己部分取代传统照明光源,全部取代指日可待,其性能与人们生活息息相关。与黄、绿色荧光材料相比,红色荧光材料还有待于进一步研究。由于良好的热稳定性和化学稳定性,宽的激发和发射光谱带,氮化物Sr2Si5N8:Eu2+红色荧光粉引起了广泛关注。但是严格的合成条件、高昂的成本限制了其在白光LED中的应用。为此,论文探索了以金属氧化物为原料的LED氮化物红色荧光粉Sr2Si5N8:Eu2+;盈和条件合成方法,通过采用田口优化设计与酒精湿磨的高能球磨工艺,对SrCO3与Si3N4展开单独球磨以及对SrCO3和Si3N4共同球磨的混料方式,藉助红外光谱、x射线衍射与荧光光谱对球磨中间产物和高温固相反应终端产物的化学键、晶体结构与荧光光谱分析表明,球磨过程中Si-N键的破损以及Si3N4原料中氧含量偏高是LED氮化物红色荧光粉Sr2Si5N8:Eu2+合成过程中产生杂相的主要原因。对此,我们采用保护Si3N4原料中Si-N键的完整性,对SrCO3单独球磨的工艺措施成功探索出利用SrCO3原料合成高纯Sr2Si5N8:Eu2+;定光粉的新工艺。论文在研究了单质复色荧光粉Li2SrSi04:Eu2+,Ce3+扣Eu2+与Ce3+之间能量关系的基础上发现现有的Li2SrSi04晶体结构(ICSD167334)认为的Li2SrSi04具有三方结构(空间群p3121(152)),其中Sr只有一种格位,不能很好地解释实验测得的Li2SrSi04:Eu2+,Ce3+的激发和发射光谱。论文采用XRD、荧光光谱、高分辨透射电子显微镜、脉冲纳秒光学参量振荡器等分析方法,结合GSAS晶体结构精修软件,解出了一种新的Li2SrSi04晶体结构,为单斜晶系,空间群为C121,其中Sr存在两种格位。针对深紫外LED应用, 论文研究了YBO3基质中发光中心Bi3+和Sb3+离子与Eu3+离子之间的能量传递关系,研究结果表明,Bi3+能够把激发能有效传递给Eu3+,但是与Bi3+具有相同ns2电子构型的Sb3+由于激发和发射带之间大的斯托克斯位移,导致Sb3+离子的发射带与Eu3+的激发带不匹配,不能将激发能有效传递给Eu3+。
[Abstract]:As the fourth generation green light source, the white LED (Light emitting Diode) light source has partially replaced the traditional lighting source in modern society, all of which will be replaced by the near future with its advantages of high efficiency, energy saving, environmental protection and low cost. Its properties are closely related to people's lives. Compared with yellow and green fluorescent materials, red fluorescent materials need to be further studied. Due to their good thermal and chemical stability, wide excitation and emission spectra, The application of nitride Sr2Si5N8:Eu2 red phosphors in white LED is limited by the strict synthesis conditions and high cost. Therefore, the paper explores the Sr2Si5N8:Eu2 nitride red phosphors using metal oxides as raw materials. By using Taguchi optimization design and alcohol wet milling technology, the mixing method of SrCO3 and Si3N4 and SrCO3 and Si3N4 are developed. The chemical bonds, crystal structure and fluorescence spectra of the intermediate products of ball milling and the end products of high temperature solid state reaction were analyzed by means of X-ray diffraction and fluorescence spectra. The damage of Si-N bond during ball milling and the high oxygen content in Si3N4 raw material are the main reasons for the formation of heterogenous phase in the synthesis of LED nitride red phosphor Sr2Si5N8:Eu2. Therefore, we protect the integrity of Si-N bond in Si3N4 raw material. The preparation of high purity Sr2Si5N8:Eu2 by using SrCO3 raw material was successfully explored in the process of single ball milling of SrCO3. Based on the study of the energy relationship between Eu2 and Ce3, it is found that the existing Li2SrSi04 crystal structure (ICSD167334) shows that the Li2SrSi04 has a tripartite structure (space group p3121t152n), in which Sr has only one lattice. The excitation and emission spectra of Li2SrSi04:Eu2 Ce3 measured by experiment can not be explained well. In this paper, XRD, fluorescence spectrum, high resolution transmission electron microscope, pulse nanosecond optical parametric oscillator and GSAS crystal structure refinement software are used. A new Li2SrSi04 crystal structure, which is monoclinic and space group C121, is obtained. For the application of deep ultraviolet LED, the energy transfer relationship between Bi3 and Sb3 ions and Eu3 ions in YBO3 matrix is studied. The results show that Bi3 can effectively transfer the excitation energy to Eu3, but Sb3 with the same ns2 electron configuration as Bi3 has a large Stokes shift between the excitation and emission bands, which leads to the mismatch between the Sb3 emission band and the Eu3 excitation band. The excitation energy can not be effectively transferred to Eu3.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN312.8

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