【作者】 罗志强；

【导师】 张孝彬；

【作者基本信息】 浙江大学 ， 材料物理与化学， 2006， 硕士

【摘要】 一维纳米材料的制备与表征是目前晶体生长领域的重要研究方向。本论文的研究涉及两种一维纳米材料:碳纳米管及ZnO纳米棒。碳纳米管具有与金刚石相同的热导性和独特的力学性质、大的长径比以及纳米尺度的中空孔道,在场发射、电极修饰、分子电子器件、探针显微镜针尖、复合材料的增强剂、气体储存、催化剂载体等众多领域具有潜在的应用前景。ZnO是一种Ⅱ-Ⅵ族化合物半导体,属六方纤锌矿结构,其禁带宽度为3.37eV,激子束缚能为60meV。ZnO在光电、压电、铁电、铁磁等诸多领域都具有优异的性能,ZnO一维纳米结构还在激光、场发射、光波导、非线性光学、光电子器件等领域有新的潜在的应用前景。由于碳纳米管和ZnO纳米棒阵列独特的性能和潜在的应用前景,它们是所有一维纳米材料中研究得最广泛最深入的两种。高纯度纳米碳管的大量制备、ZnO纳米棒阵列的大规模制备及其掺杂则是它们被广泛应用的前提。 本论文简要综述了碳纳米管和氧化锌纳米棒的形貌、结构、物理性能、制备方法及其生长机理。以纳米碳酸钙作为催化剂载体,应用CVD法制备了碳纳米管,并详细研究了实验参数对碳纳米管合成的影响。应用化学溶液沉积法在由溶胶凝胶法制备的ZnO/Si衬底上制备了ZnO纳米棒阵列,并研究了其反应机理。应用低温水热法在ZnO/Si衬底和ZnO/Al衬底上分别制备了ZnO纳米棒和ZnO:Al纳米片阵列,并对ZnO纳米棒阵列的Ni和Co元素的水热掺杂进行了初步研究。 为了使CVD法合成的粗产物易于纯化,本文详细研究了纳米碳酸钙载体负载金属催化剂,裂解乙炔合成碳纳米管的实验参数研究,包括金属催化剂的种类和含量、反应温度和时间等。实验结果表明,产物不仅易于纯化,而且提纯工艺不会破坏碳纳米管表面的结构特征。碳纳米管的产率明显地受到了催化剂和催化剂载体热稳定性的影响。高温条件通常有利于碳氢气体的裂解和金属催化剂活性的发挥,但是纳米碳酸钙载体的分解程度也随温度的升高而加剧,从而影响到金属催化剂的团聚和分布,并导致碳纳米管产率的降低。因此,为了保证碳纳米管的产率,一个适当的中等的反应温度是必需的。 采用溶胶凝胶法在Si基底上制备ZnO前驱体薄膜(pre-coating film),经热处理后采用化学溶液沉积法在上述制备的ZnO/Si衬底上制备了窄直径分布、晶体取向高度一致的ZnO纳米棒阵列。这种方法具有大面积、大批量、工业化生产ZnO纳米棒阵列膜的潜力。促使ZnO一维生长的主要机制是低过饱和度机制。反应溶液中,ZnO晶体在ZnO/Si衬底的纳米ZnO更多还原

【Abstract】 Recently, synthesis and characterization of one-dimensional （1D） nanostructures have become the focus of intensive research in crystal growth. In this thesis, two kinds of 1D nano-materials , i.e. carbon nanotubes （CNTs） and ZnO nanorods, have been synthesized. Many potential applications have been proposed for CNTs , including field emission displays, modified electrodes, nanometer-sized semiconductor devices, probes, high-strength composites, energy storage and energy conversion devices and catalysts support, based on their good thermal conductivity similar to diamond, the special mechanical property, the high aspect ratio and hollow structure with nano-scale of carbon nanotubes. Zinc oxide （ZnO） is a novel II -VI compound semiconductor with a wide direct bandgap （3.37ev）, a high excitation binding energy （60mev） and a hexagonal wurtzite structure. ZnO is a unique material that exhibits optoelectronic, piezoelectronic, ferroelectric and ferromagnetic multiple properties, and many new potential applications have been proposed for its 1D nanostructures, including laser, field emission of electron, wave-guide of photons, non-linear optics and optoelectronic devices. However, the mass production of high quality CNTs, doping and synthesis of ZnO 1D nanostructures in large scale are the preconditions of their applications.In the thesis, the morphologies, structures, physical properties, preparation methods and growth mechanism of CNTs and ZnO nanorods were briefly reviewed. The syntheses of CNTs by CVD method using nanocrystalline CaCO₃ as catalyst support were discussed in details, especially the effects of experimental parameters on the CNTs syntheses. Moreover, well-aligned ZnO nanorod arrays were fabricated by chemical solution deposition on Si substrate （ZnO/Si substrate） which was spin coated with ZnO sol as nucleation seeds, and the growth mechanism of the ZnO nanorod arrays was discussed in details. ZnO nanorod arrays and ZnO:AI nanoplate arrays were respectively prepared on ZnO/Si and ZnO/Al substrates by a low temperature hydrothermal method. The possibility of using this hydrothermal method to synthesize Zn_1-xCo（Ni）_xO diluted magnetic semiconductor was also discussed.In order to easily remove catalyst impurities, nanocrystalline CaCO₃ was used as catalyst support. Some important parameters were investigated in the thesis, such as composition and content of metallic catalyst, reaction temperature and time, et al. The purification of the rawproduct could be achieved in one step, possessing little structural destructivity. The yield of CNT was greatly affected by the stability of the catalyst and its support at reaction temperature. Though a higher temperature usually results in a larger extent of disassociation of hydrocarbon gas and a better activation of catalytic metal, the disintegration of calcium carbonate was also strongly correlated to the elevated temperature. The distribution and agglomeration of the catalytic nanoparticles tightly depended on the condition of catalyst support. The rapid decomposition of the catalyst would decrease the CNT yield. So a moderate temperature is necessary for a high CNT yield.Mono-dispersed and well-aligned ZnO nanorod arrays were fabricated by chemical solution deposition on Si substrate （ZnO/Si substrate） which was spin coated with ZnO sol as nucleation seeds. This facile technique greatly facilitates the approach to scale-up fabrication of aligned ZnO nanorods with relative low-cost at a remarkably low temperature. The growth mechanism of ZnO nanorod is anisotropic growth, kinetically controlled by low super-saturation. In the reaction system, heterogeneous nucleation occurs firstly on nano-ZnO film of the substrate, and the growth process of ZnO nanorods is actually continuing the growth of grain of nano-ZnO film. The nano-ZnO film of substrate has critical influence on the morphology of ZnO nanorod arrays. The uniformity of morphology, distribution of diameters and orientation of ZnO nanorods are controllable by adjusting the process of nano-ZnO film substrates.Highly aligned ZnO nanorod arrays with a narrow diameter distribution of the ZnO nanorods were fabricated on ZnO/Si substrate by a low temperature hydrothermal method. The average diameter of the ZnO nanorods increases with the higher concentration of the aqueous. The process to prepare ZnO/Si substrates also has strong influence on the orientation and distribution of the diameter distribution of the ZnO nanorod arrays. In the same reaction aqueous, ZnO:Al nanoplate arrays have been synthesized on the ZnO/Al substrates. The ZnO:Al nanoplates are single-crystalline with wurtzite structure, and the normal direction of the nanoplate is [001]. Al ions doping is considered as an important role in the growth of the ZnO: Al nanoplates, which was also proved in another reaction system. Using this hydrothermal method, the Co and Ni elements could not be doped into the ZnO nanorods by only elevate the synthesis temperature.更多还原