中国科学技术大学
博士学位论文
姓名：***
申请学位级别：博士
专业：无机化学
指导教师：***
20100420
摘要
本论文旨在探索利用晶体结构来控制性的构建一些具有特殊尺寸、特殊形貌和图案的高度规则的无机多级微纳结构材料，结合“自上而下”（Top-Down）和“自下而上”（Bottom-Up）的方法，通过反应物和目标产物的结构分析来设计性的可控合成特定纳米材料的特定形貌，这种路线不仅对我们了解纳米材料合
成提供了另外一个途径，同时也给理论分析纳米材料的形成本质原因提供了可能的理想指导。本论文的主要研究内容如下：
1. 作者通过利用了晶体结构的自范性和刻蚀机理结合的方法，也就是所谓的“自上而下”（Top-Down）的方法来构建分级制结构的PbSe纳米晶体。该PbSe 分级制结构形成是碱性诱导下的刻蚀与刚性分子1,10-phen吸附保护竞争的结果。通过大量的实验优化了反应的动力学因素，使得该结构具有良好的重复性、较高的产率和可操控性，为以后的性质研究提供了保证。采用“自上而下”（Top-Down）的方法来构建分级制结构的方法，也为其他材料分级制结构的构建提供了思路。
2. 作者首次采用维生素C热解的方法来构筑肾结石成份之一的四方相的水合草酸钙，整个过程中不需要利用机添加剂来调节晶体的生长，该微晶具有规则的四方棱柱形貌，且结晶性好。并采用“自上而下”（Top-Down）固相制备方法来获得相应四方棱柱状的多孔碳酸钙，并研究了多孔碳酸钙对无机水合盐类相变材料的限域效应。合成的多孔碳酸钙是无毒且环境友好的，将其应用到无机盐相变领域能够成功地解决无机水合盐相变过程中遇到的常见难题，如相分离和过冷现象.这也表明多孔碳酸钙有可能应用于未来的“智能屋”中。
3. 作者利用晶体生长的各向异性，在外加表面活性剂的条件下，通过“自下而上”（Bottom-Up）的方法实现了一维纳米结构在三维空间的自组装，实现了晶体生长的各向异性和Ostwald熟化机理的完美结合。
使用该法首次获得了大量花状结构的VO2。这种特殊结构的VO2纳米材料作为水相锂离子电池的电极材料呈现出了良好的锂电性质。
4. 作者对钒氧化合物材料中四价的VO2体系进行了设计性合成并对其不同的晶体结构进行了X射线精细吸收结构光谱的初步研究。我们成功地利用简单的水热合成方法实现了对VO2（A）和VO2（B）两相的可控合成，阐明了两相之间的转化关系。进一步地，晶体结构分析和第一性原理计算表明VO2（A）比VO2（B）更稳定。这为进一步研究通过结构特点来控制VO2材料的合成奠定了基础。关键词：自上而下 自下而上 分级制结构 结构与性能相关
ABSTRACT
In this dissertation, our goal is to explore to construct higher ordered micro-/nanostructures with specific sizes, shapes, and hierarchies by applying either “top-down” way or “bottom up” way. Moreover, based on understanding the morphology and crystal structural characteristics of the final product, the corresponding structure-dependent properties of the as-obtained inorganic hierarchical micro-/nanomaterials were also investigated in our dissertation. The main parts of the results are summarized briefly as follows:
1. Based on the self-modeling of the product’s crystal and the “top-down” way on the basis of an etch
ing process, we successfully realized the construction of PbSe hierarchical superstructures. The formation process involves the competition between protection of 1, 10-phen and etching of OH- induced etching in crystal facet of PbSe. This facile “top-down” way on the basis of an etching process could also be extended to the preparation of other hierarchical superstructures of functional inorganic materials.
2. For the first time, the authors developed a new and convenient route to plant high-quality calcium oxalate dehydrate (COD) tetragonal prisms from the C2O42-source of slow decomposition of L-ascorbic acid. Furthermore, the COD crystals which were obtained in the absence of commonly used polymers or surfactants show impressive higher ordered tetragonal prisms. Subsequently, using COD tetragonal prisms as an important in-situ template, we reasonably design a top-down solid-phase strategy to successfully fabricate macroscaled porous CaCO3 tetragonal prisms with different pore sizes. The as-obtained CaCO3 tetragonal prisms with the different pore sizes are overall safe and environment-friendly, and the application of non-toxic nanoarchitectures as support matrix successfully mitigates the common problems for phase change materials of inorganic salts such as phase separation and supercooling-effect, showing the prospective signs for the application of energy-saving field in the future “smart-house” systems.
生活中最常见纳米技术
3. The authors successfully developed the combination of the anisotropic growth of the product’s crystal and the “bottom-up” route on the basis of self-assembly process to realize the assembly of one dimensional nanostructures into three dimensional hierarchical flowerlike micro-/nanostructures. Novel flowerlike VO2 (B) micro-/nanostructures were synthesized on a large scale by the perfect combination of
both the anisotropic growth of crystal and Ostwald ripening mechanism. Electrochemical measurements predict that flowerlike VO2 (B) possesses favorable discharge capacity, and capacity retention, which suggest its potential applications in cathode materials for aqueous lithium-ion batteries.
4. Pure single-crystalline metastable tetragonal VO2 (A) and monoclinic VO2 (B) phase nanostructure have been successfully synthesized via one-step hydrothermal method by hydrolysis of VO(acac)2. It is found that the phase composition (ratio of VO2 (A) to VO2 (B)) of the products increases with increasing the reaction temperature. Therefore, VO2 nanostructure with controlled phase compositions can be obtained in high yields. Both structural analysis and the first-principle calculations reveal the formation from VO2 (B) to VO2 (A) shows a crystallographic shear mechanism. X-ray absorption fine structure spectroscopy (XAFS) has been used as the basic analyti
c tool. For the first time, X-ray absorption spectroscopy (XAS) of the V L edge and O K edge was performed on the different VO2 phase. Here, we gave the electronic structures of two different kind of VO2.
Key Words: top-down, bottom-up, hierarchical structure, structure- related properties
中国科学技术大学学位论文原创性和授权使用声明
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作者签名：___________
2010年4 月20 日
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