等离子体宏量制备一维纳米结构材料及其性能研究
文献类型：学位论文
| 作者 | 胡鹏 |
| 学位类别 | 博士 |
| 答辩日期 | 2008-01-11 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 过程工程研究所 |
| 导师 | 陈运法 |
| 关键词 | 一维纳米材料 等离子体 宏量制备 掺杂 晶体结构 |
| 其他题名 | Plasma Synthesis and Property Characterization of Large Quantities of One-Dimensional Nanostructured Materials |
| 学位专业 | 化学工程 |
| 中文摘要 | 一维纳米材料由于其在基础研究以及纳米器件方面潜在的应用，使得人们对其合成、表征及物性研究产生了极大的兴趣。传统气相法和液相合成方法存在反应时间长、产物纯度不高以及产量低等缺点。本论文利用高频常压热等离子体快速宏量制备了一维结构纳米材料，并对其生长机理及性能进行了探讨，主要研究内容如下： 1. 利用等离子体合成方法一步连续制备了具有不同结构的一维纳米氧化锌及硫化锌，其产量超过了100g/h，并且晶体生长速度比传统气相法提高了约一百倍。确立了过程参数对产物形貌的影响规律，得到了具有可控长径比的纳米棒、四针状以及多针状一维结构纳米氧化锌；四针状、纳米棒、纳米带、纳米片一维纳米硫化锌及其空心结构。显微结构分析显示得到的产物均为单晶结构。光催化测试结果表明长度为2 μm的纳米棒由于氮的掺杂在紫外光区以及可见光区均展现了优异的光催化活性，因此，可适合于光催化领域的应用。 2. 提出了扩散传质控制的双向自由的气-固(VS)生长机理(two-dimensional and wall-free growth mechanism)，并通过极端条件实验验证了其生长机理，得到了具有明显双向尖端的一维氧化锌纳米结构。通过对生长模型的分析可知，氧化锌纳米棒的形成是通过{ZnO4}6-四面体沿着C轴双向重复堆积而成，而四针状纳米结构形成是由八个{ZnO4}6-四面体形成的八面体孪晶通过应力释放及针体的生长，沿四个[0001]方向生长而成。 3. 通过对氧化锌以及硫化锌晶体结构的分析，得出了等离子合成条件下晶体学结构控制的一维结构生长的规律。六方晶系的极性晶体在生长过程中受到各向异性键的控制，在接近热力学平衡条件下生长时容易通过极轴方向生长从而形成一维纳米结构。通过对具体材料的合成制备证实了理论的正确性。因此等离子合成过程提供了一种快速、宏量制备六方极性晶体一维纳米结构的方法。此外等离子高过程温度以及其可调的高活性气氛，可以制备在常规条件下难以得到的一维纳米结构材料，扩大了气相法制备一维纳米结构材料的范围。 4. 利用金属氯化物与原料共蒸发的方法，成功地制备了具有不同形貌的过渡金属（包括Mn、Ni、Cu、Co）掺杂的氧化锌以及硫化锌一维纳米结构，研究了掺杂元素对产物形貌以及性能的影响，得到了具有室温铁磁性能的Mn掺杂的ZnO纳米棒。此外，0.5%Mn掺杂的氧化锌纳米棒展现了优异的可见光催化性能。 |
| 英文摘要 | In the past several years, the synthesis, characterization and properties of one-dimensional (1D) nanoscale materials have stimulated great interest due to their attractive prospects in fundamental physical science and potential nano-device applications. However, the main drawbacks of conventional vapor deposited process and wet-chemistry routes are the small-scale quantities, long reactive time and impurity which made obstacles to further investigation and application of 1D nanostructures. In this thesis, different 1D nanostructures were selectively synthesized by plasma process, and their growth mechanism and properties were also investigated. The main results are summarized as follows: 1. 1D nanoscale ZnO and ZnS with different structures were successfully synthesized in a one step, continuous, and scaleable way by thermal evaporation of different starting materials, with closely controlled aspect ratio. The quantities of final products are more than 100 g/h, and crystal growth rate increased 100 times than that of the conventional vapor process. 1D nanostructures with different morphology, including ZnO nanorods, tetrapods and multi-pods, ZnS nanorods, nanobelts, nanoslices and tetrapods were obtained, and the influences of process parameters on the morphology of final products were investigated. The results reveal that the synthesized 1D nanostructures are single crystalline, and ZnO nanorods with length about 2 μm show excellent photocatalytic activities under UV and visible light irradiation, accordingly, they could be used in the photocatalytic field. 2. A collision-controlled two-dimensional and wall-free Vapor-Solid (VS) growth mechanism was first proposed to explain the growth process that occurred exclusively in the gas current by a flowing way, and the growth mechanism was proved by the contrasting experiment taken under extreme parameters and double-direction needlelike ZnO nanostructures were obtained. The growth model was established to explain the formation of 1D nanostructures. The nanorod was formed by stacking of {ZnO4} tetrahedra along the +C axis, and the formation of the tetrapod has two stages. Firstly, the {ZnO4} tetrahedron stacks into octahedral multiple twins structure. Secondly, the octa-twins structures grow into tetrapod crystal along the [0001] direction due to strain relaxation. 3. Anisotropic structure controlled 1D crystal growth under plasma process was concluded by analyzing the crystal structure of ZnO and ZnS. The hexagonal-structured crystals are preferential growth along their polar axis due to the anisotropic bonding in the crystallographic structure, and the conclusion was confirmed by the practical experiment. The present method provides a facile way to synthesize hexagonal-structured 1D nanostructures in a rapid, simple, and scalable way, and other hexagonal-structured materials could be achieved due to the high temperature and tunable atmosphere in plasma system. 4. ZnO:Mn+ (M=Mn, Ni, Cu, Co) and ZnS:Mn+ (M=Ni, Mn) single-crystal 1D nanostructures have been prepared via simple halide-transport chemical vapor process. The influences of doping element on the morphology and properties of synthesized products were investigated, and magnetism analysis reveals that the synthesized nanostructures all exhibit ferromagnetism under normal temperature. In addition, the 0.5% Mn doped ZnO nanorods show excellent photocatalytic activities under visible light irradiation. Accordingly, the present method is also suitable for large-scale synthesis of transition metal doped 1D nanostructures. |
| 语种 | 中文 |
| 公开日期 | 2013-09-13 |
| 页码 | 165 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1173]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 胡鹏. 等离子体宏量制备一维纳米结构材料及其性能研究[D]. 过程工程研究所. 中国科学院过程工程研究所. 2008. |
入库方式： OAI收割
来源：过程工程研究所
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