稀土掺杂二氧化钛纳微米晶体的可控合成及发光性质研究

发布时间：2018-04-24 13:33

本文选题：TiO2 + 稀土掺杂　；参考：《吉林大学》2015年博士论文

【摘要】：在过去的数十年中，因为稀土掺杂的纳微米材料在荧光粉、先进平板显示器、生物和化学标签等领域具有潜在的应用价值，所以它们受到了研究学者的广泛关注。TiO2作为半导体材料中应用最广的一种，它具有特殊的晶体结构、高折射率、低声子能量、足够的热学和环境稳定性等特点，因此将其用作稀土掺杂的主体材料已经被广泛的研究。众所周知，材料的物理、化学性质和其形貌密切相关，因此可控的合成具有特定尺寸、维度和结构的TiO2纳微米功能材料已经成为了当前的研究热点之一。本论文用水热和溶剂热法合成了多种形貌的稀土掺杂TiO2纳微米材料，通过X射线衍射仪、傅里叶红外光谱仪、扫描电子显微镜、透射电子显微镜、和选区电子衍射仪等手段对样品进行了表征测试。此外，通过荧光光谱系统的研究了各种稀土掺杂TiO2纳微米材料的发光机理和影响样品发光性能的因素。主要的研究工作包括以下几个方面： 1、以柠檬酸和乙二胺作为晶面控制剂，通过一种容易的水热合成路线制备了具有高结晶度和形貌一致的TiO2:Eu3+纺锤形纳米棒。实验结论表明柠檬酸和乙二胺的加入量能够明显的影响所得样品的形貌和尺寸。在最佳实验条件下所得的纳米棒为纺锤形结构，中心直径为60nm，长度为460nm。在紫外光激发下，未经过后续煅烧处理的TiO2:Eu3+纺锤形纳米棒显示红光发射，这对应于Eu3+的5D0-7F2跃迁。以相同的激发波长激发两种不同形貌的TiO2:Eu3+样品，可以发现TiO2:Eu3+纺锤形纳米棒比TiO2:Eu3+纳米粒子具有更高的发光强度。这主要是由于纳米粒子相比纳米棒具有更多的表面缺陷引起的。此外，通过低温位置选择光谱证明了Eu3+在TiO2晶体中处于无序的表面位置。 2、通过简单的水热法制备了一种新颖的三维（3D）花状TiO2:Eu3+微球。经过随后的高温煅烧过程（500oC，3h），其花状形貌能够完整的保持，且能得到具有高结晶度的锐钛矿晶相。扫描电镜图像显示，所得的三维花状TiO2:Eu3+微球样品表面呈现宽松多孔的花状结构，并且是由不规则形状的表面光滑的纳米片交叉组装而成，纳米片的厚度大约为10nm。根据所得样品的扫描电镜图像发现，柠檬酸（H3Cit）、乙二胺（En）和氢氟酸（HF）在花状微球的形成过程中起到至关重要的作用。此外，在紫外光激发下，煅烧后得到的三维花状TiO2:Eu3+微球样品展现了优良的红光发射，这对应于Eu3+的5D0-7F2跃迁发射。 3、以碳球为硬模板，钛酸四丁酯为钛源，乙醇为溶剂，聚乙烯吡咯烷酮为分散剂，硝酸钐为钐源，通过一种简单的溶剂热法制备了C@TiO2:Sm3+核壳微球，在电阻炉中煅烧得到TiO2:Sm3+空心球。XRD结果显示，在500°C煅烧2h所得的TiO2:Sm3+空心球为锐钛矿相。透射电镜显示，，样品为尺寸均一的空心球结构，空心球内径为55-75nm，壳层厚度为10-14nm。在紫外光激发下，TiO2:Sm3+空心球发射出特有的橙红色光，这与Sm3+的特征发射（4G5/2-6H7/2）相一致。此外，TiO2:Sm3+空心球的发光强度与Sm3+的掺杂浓度密切相关，当Sm3+的掺杂浓度为2mol%时，TiO2:Sm3+空心球有最强的荧光发射。 4、用EDTA作为螯合剂，通过一种简单方便的水热法成功制备了三维TiO2和TiO2:Eu3+核壳微球。XRD结果显示，经过水热反应得到的样品不需经过煅烧就表现为锐钛矿晶相。所得产物由许多不规则形状的直径为0.5-1.5μm的核壳微球组成。这种核壳微球的比表面积达到了134.32m2/g，远远高于P25的比表面积(50±15m2/g)。表面积大导致样品具有大量的表面缺陷，因此在紫外光激发下，由于能量经过非辐射跃迁的损失使TiO2:Eu3+核壳微球几乎不发光。然而，在紫外光的照射下，TiO2核壳微球对甲基橙水溶液具有良好的光催化降解效果，远远强于常用的光催化剂P25。这与样品具有大的表面积密切相关，大的表面积使样品表面具有更多的表面活性位点并能够吸附更多的染料分子。因为其具有优良的光催化活性，所以在降解废水中的有机染料方面有广阔的应用前景。
[Abstract]:Over the past few decades, rare earth doped nanofilms have potential applications in the fields of phosphors, advanced flat panel displays, biological and chemical labels, so they have been widely concerned by researchers as one of the most widely used.TiO2 materials, with special crystal structure, high refractive index, and high refractive index. Low phonon energy, sufficient thermal and environmental stability, so it has been widely studied as the main material of rare earth doping. It is well known that the physical and chemical properties of the materials are closely related to their morphology. Therefore, the TiO2 nano functional materials with specific dimensions, dimensions and structures have become the present. One of the hotspots of research.
In this paper, a variety of rare earth doped TiO2 nanometer materials were synthesized with water heat and solvothermal method. The samples were characterized by means of X ray diffractometer, Fourier infrared spectrometer, scanning electron microscope, transmission electron microscope, and electoral electron diffractometer. The mechanism of luminescence and the factors affecting the luminescence properties of TiO2 doped nanmicron materials are mainly studied.
1, with citric acid and ethylenediamine as the crystal control agent, the TiO2:Eu3+ spindle shaped nanorods with high crystallinity and the same morphology were prepared through an easy hydrothermal synthesis route. The experimental results show that the addition of citric acid and ethylenediamine can obviously affect the shape and size of the obtained samples. The rice rod is a spindle shaped structure with a center diameter of 60NM, and the length of 460nm. is excited by ultraviolet light, and the TiO2:Eu3+ spindle nanorods without subsequent calcinations show red light emission. This corresponds to the 5D0-7F2 transition of Eu3+. With the same excitation wavelength, two different morphologies of TiO2: Eu3+ samples can be excited, and TiO2:Eu3+ spinning nanorods can be found. The luminescence intensity is higher than that of TiO2:Eu3+ nanoparticles. This is mainly due to the more surface defects of nanorods than nanorods. In addition, the location of Eu3+ in the TiO2 crystal is proved to be in a disordered surface by the low temperature position selective spectroscopy.
2, a novel three-dimensional (3D) flower like TiO2:Eu3+ microsphere was prepared by a simple hydrothermal method. After the subsequent high temperature calcination process (500oC, 3H), the flower morphology of the microspheres could be kept intact and the crystalline phase of anatase with high crystallinity was obtained. The scanning electron microscope images showed that the surface of the three-dimensional flower like TiO2:Eu3+ microspheres showed loose surface. The porous, flower like structure is formed by the cross assembly of irregular surface smooth nanoscale. The thickness of the nanoscale is about 10nm., according to the scanning electron microscope images of the obtained samples, the citric acid (H3Cit), the ethylenediamine (En) and the hydrofluoric acid (HF) play a vital role in the formation of the flower shaped microspheres. The three dimensional flower like TiO2:Eu3+ microspheres samples prepared by calcination showed excellent red emission, corresponding to the 5D0-7F2 transition emission of Eu3+.
3, using carbon sphere as a hard template, four butyl titanate as a titanium source, ethanol as a solvent, polyvinylpyrrolidone as a dispersant, samarium nitrate as a samarium source, C@TiO2:Sm3+ nuclear shell microspheres were prepared by a simple solvent heat method. The result of the calcined TiO2:Sm3+ hollow sphere.XRD results in a resistance furnace showed that the TiO2:Sm3+ hollow spheres obtained from the calcined 2h of 500 degree C were anatase. The transmission electron microscope shows that the sample is a homogeneous hollow sphere structure, the inner diameter of the hollow sphere is 55-75nm, the shell thickness is 10-14nm. excited by the ultraviolet light, the TiO2:Sm3+ hollow sphere emits unique orange red color light, which is in accordance with the characteristic emission of Sm3+ (4G5/2-6H7/2). In addition, the luminescence intensity of the TiO2:Sm3+ hollow sphere is closely related to the doping concentration of Sm3+. Cut correlation, when the doping concentration of Sm3+ is 2mol%, the TiO2:Sm3+ hollow spheres have the strongest fluorescence emission.
4, using EDTA as a chelating agent, three dimensional TiO2 and TiO2:Eu3+ core shell microspheres have been successfully prepared by a simple and convenient hydrothermal method. The results show that the samples obtained by hydrothermal reaction are anatase phase without calcination. The product is composed of a number of irregular shaped nuclear shell microspheres with a direct diameter of 0.5-1.5 micron. The core shell is a core shell. The specific surface area of the microspheres reached 134.32m2/g, far higher than the specific surface area of P25 (50 + 15m2/g). The large surface area caused the samples to have a large number of surface defects. Therefore, under ultraviolet light, the TiO2:Eu3+ nuclear shell microspheres were almost not luminescent due to the loss of energy through the non radiation transition. However, under ultraviolet light, the TiO2 core shell microspheres were used. Methyl orange aqueous solution has a good photocatalytic degradation effect, far stronger than the common photocatalyst P25. which is closely related to the large surface area of the sample. The large surface area makes the surface of the sample more surface active site and can adsorb more dye molecules. Because of its excellent photocatalytic activity, the wastewater is degraded in the wastewater. The organic dyes are widely used in the future.

【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TB383.1;O614.411

【参考文献】