氧化物同轴纳米电缆的组装技术及其光学性能的研究

发布时间：2019-03-21 20:07

【摘要】：随着纳米材料在人们日常生产生活中的广泛应用,氧化物同轴纳米电缆作为其中独特的一员,集核壳异质结构和纳米材料的基本特性于一体,在近年来成为一个新的研究热点。ZnO禁带宽度为3.37 eV,激子束缚能高达60 meV,是能够吸收紫外光至可见光的廉价氧化物。纳米ZnO由于存在大量缺陷,在常温下易发出蓝绿光,广泛的应用于荧光材料。Y_2O_3具有耐热,抗腐蚀、高温稳定性,高介电常数等优异的光学性能。掺入三价Eu~(3+)后,是一种优良的红色荧光材料。结合同轴纳米电缆结构特性及以上各类材料发光性能,能够通过调整外部激发条件或内部物质含量调整材料的发光性能,实现白光发光。本文主要通过利用XRD、SEM、TEM、PL等现代材料研究方法对制备的材料的物象、微观结构、光学性能以及材料的结构——性能之间的联系进行的表征和分析。具体工作内容如下:1.采用氧化铝模板先电辅助沉积后溶胶凝胶法制备Eu_2O_3/ZnO同轴纳米电缆,ZnO壳层厚度为15 nm,芯层直径为30 nm。ZnO为纤锌矿结构、Eu_2O_3为体心立方结构。在200 nm~500 nm波长激发下,发射光谱中出现随着激发波长降低而降低的ZnO带隙发光(380 nm)与间隙锌绿光发射平台(400 nm~500 nm)。在200 nm~245 nm波长范围内激发下,出现宽的Eu~(3+)离子的~5D_0→~7F_1为主的跃迁,证实了系统存在能量电荷转移和能量传输的过程。在250 nm~295 nm波长范围内激发下,发光以Eu~(3+)的~5D_0→~7F_2跃迁为主。395 nm和465 nm激发下存在Eu_2O_3的~7F_0→~5L_6和~7F_0→~5D_2跃迁直接吸收,出现反常的黄光和红光发射。发射峰强度和位置随着激发波长的改变而改变,实现了通过调整外界条件,调制同轴电缆的发光性能。在280 nm激发下,Eu_2O_3/ZnO同轴纳米电缆发出白色的光。2.采用氧化铝模板先电辅助沉积,后溶胶凝胶法,制备ZnO:Tb~(3+)/Y_2O_3:Eu~(3+)同轴纳米电缆,壳层厚度为20 nm,芯层直径为30 nm。250 nm波长激发下,发射光谱中ZnO绿光发射很强证明了同轴纳米电缆存在大量缺陷。以554 nm和612 nm为监控波长的激发光谱中出现均出现氧空位吸收峰,证实了氧空位参与与稀土离子之间的能量传递。同时出现较强的Eu~(3+)离子的~7F_0→~5D_2跃迁,证明了材料中Eu~(3+)大部分进入Y_2O_3非反演对称中心C_2位置。250 nm波长激发下随着Eu~(3+)掺杂量的增加,红色荧光随之增加。Tb和Eu的摩尔比在4:2和5:2时样品实现白光发射。实现了通过改变内部稀土含量,调制纳米电缆的发光性能。
[Abstract]:With the wide application of nano-materials in people's daily production and life, oxide coaxial nanowires, as one of the unique members, integrate the core-shell heterostructure and the basic properties of nano-materials in one. The band gap of 3.37 eV, exciton binding energy up to 60 meV, is a cheap oxide which can absorb ultraviolet light to visible light. Due to a large number of defects, nano-ZnO is easy to emit blue-green light at room temperature, and is widely used in fluorescent materials. Y _ 2O_3 has excellent optical properties such as heat resistance, corrosion resistance, high temperature stability, high dielectric constant and so on. Doped with trivalent Eu~ (3), it is an excellent red fluorescent material. Combined with the structure characteristics of coaxial nanowires and the luminescent properties of all kinds of materials above, white luminescence can be achieved by adjusting the external excitation conditions or the content of internal materials to adjust the luminescent properties of the materials. In this paper, the object image, microstructure, optical properties and the relationship between the structure and properties of the prepared materials are characterized and analyzed by means of modern material research methods such as XRD,SEM,TEM,PL and so on. The specific contents of the work are as follows: 1. Eu_2O_3/ZnO coaxial nanowires were prepared by alumina template electrodeposition followed by sol-gel method. The thickness of ZnO shell was 15 nm, core layer diameter was 30 nm.ZnO wurtzite structure and Eu_2O_3 was body centered cubic structure. At 200 nm~500 nm wavelength excitation, ZnO band gap luminescence (380 nm) and gap zinc green emission platform (400 nm~500 nm).) appear in the emission spectrum, which decrease with the decrease of excitation wavelength. Under excitation in the wavelength range of 200 nm~245 nm, the transition of the wide Eu~ (3) ion is dominated by the ~ 5D_0 ~ 7F_1, which proves that there is a process of energy charge transfer and energy transfer in the system. Under the excitation in the wavelength range of 250 nm~295 nm, the ~ 5D_0 ~ 7F_2 transition of Eu~ (3) is dominant. The ~ 7F_0 ~ 5L_6 and ~ 7F_0 ~ 5D_2 transitions of Eu_2O_3 are directly absorbed under the excitation of 395 nm and 465 nm. Abnormal yellow and red emission occurs. The intensity and position of the emission peak change with the change of the excitation wavelength, and the luminescence performance of the coaxial cable is modulated by adjusting the external conditions. Under the excitation of 280 nm, Eu_2O_3/ZnO coaxial nanowires emit white light. The ZnO:Tb~ _ (3) / Y _ 2O _ 2O _ 3 / EU ~ (3) coaxial cable was prepared by alumina template electrodeposition and then sol-gel method. The thickness of the shell layer was 20 nm, and the diameter of the core layer was 30 nm.250 nm. The strong green emission of ZnO in the emission spectrum proves that there are a lot of defects in coaxial nanowires. Oxygen vacancy absorption peaks appeared in the excitation spectra with 554 nm and 612 nm as monitoring wavelengths, which confirmed that oxygen vacancies were involved in the energy transfer between rare earth ions and oxygen vacancies. At the same time, strong ~ 7F_0 ~ 5D_2 transitions of Eu~ (3) ions are observed. It is proved that most of the Eu~ (3) in the material enters the position of C ~ (2 +) at the asymmetric symmetry center of Y_2O_3. Under the excitation of 250 nm wavelength, the doping amount of Eu~ (3) increases with the increase of the doping amount of Eu~ (3). The red fluorescence increases and the molar ratio of TB and Eu is 4:2 and 5: 2. The white light emission of the sample is achieved. The luminescent properties of nanowires are modulated by changing the content of inner rare earth.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1

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