【作者】 黄阳；

【导师】 唐成春； 顾长志；

【作者基本信息】 华中师范大学 ， 凝聚态物理， 2006， 硕士

【摘要】 自1991年Iijima合成纳米碳管以来，一维纳米材料因为其所具有的独特性质，使之在磁学、电子学、光学、催化以及化学传感器等方面呈现出广阔的应用前景。不断开拓并完善一维纳米材料的制备方法，以及推动对一维纳米材料特殊性能的研究和应用是当前纳米科技研究与发展的关键。本论文结合不同方法，合成并表征了几种具有特殊性能的一维纳米材料，探索了这些一维纳米材料的形成机理，并对所合成的一维纳米材料电学磁学性质进行了初步研究。论文的主要创新性结果如下： 1、提供了一种在碳纳米管表面包覆金属氧化物的比较通用的方法——醇热法。利用这种方法分别制备了Fe₂O₃、La₂O₃以及CeO₂包覆的碳纳米管一维复合结构。对材料表征显示碳管上的氧化铁包覆层是由许多取向杂乱的非晶针状Fe₂O₃以及少量晶化Fe₂O₃颗粒构成，而氧化镧以及氧化铈包覆层则一般具有均匀且致密的多晶结构。系统考察了硝酸氧化、醇热环境等在包覆过程中的重要作用，提出了可能的包覆机理。发现与块体γ-Fe₂O₃相比，包覆在碳纳米管上的氧化铁的矫顽力得到了显著增强。 2、在有三氧化二铝支撑的铁催化剂存在的情况下，将GeO₂与乙烯和氨气的混合还原性气体在750℃反应，制备了表面光滑和表面覆盖有无定性碳的单晶Ge纳米线。通过对纳米线结构和成分的分析，指出了碳包覆Ge纳米线是按照气-液-固生长机理形成的。 3、利用金属Ga与水蒸气反应，按照气-液-固生长机理制备了大量直径分布均一的Ga₂O₃纳米线，并对纳米线的结构成分进行表征。对单根氧化镓纳米线电学研究表明，利用聚焦离子束辅助沉积的Pt电极与Ga₂O₃纳米线之间存在肖特基势垒，基于电子束光刻技术，在单根Ga₂O₃纳米线上制备的Au／Ti电极与纳米线实现了较好的欧姆接触。单根氧化镓纳米线的电导对氨气以及NO₂气体非常敏感。更多还原

【Abstract】 Since the discovery of carbon nanotubes by Iijima in early 1990’s, one-dimensional nanomaterials have attracted much attention due to their unique physical, chemical and biological properties as well as their potential applications in highly active catalysts, magnetic recording media, novel fluorescent materials, building blocks for nanodevices and so on. In this dissertation, we synthesized some one-dimensional nanostructures by different methods, including metal oxide coated carbon nanotubes, carbon coated germanium nanowires and Ga₂O₃ nanowires. The magnetic of metal oxide coated carbon nanotubes and electrical properties of the individual Ga₂O₃ nanowires were also addressed. The significant results achieved in this dissertation are given as follows:1. Methanol-thermal method was proposed as an effective way of completely coating carbon nanotubes with various metal oxides including needle-like Fe₂O₃, uniform La₂O₃ and CeO₂. Based on the system investigation, we predicated that the pre-oxidation of CNTs and the acid-based methanol solution were extremely important in the coating process, and a possible mechanism was also proposed. Preliminary study of magnetic property shows that the coercivity of iron oxide has been enhanced after coating on carbon nanotubes.2. Reacting of GeO₂ with mixed reducing gas of C₂H₄ and NH₃ in the presence of Fe/Al₂O₃ catalysts at 750℃, we synthesized single- crystalline Ge nanowires covered with amorphous carbon in one step. The growth mechanism of the Ge nanowires could be attributed to the well-known vapor-liquid-solid （VLS） catalytic growth process promoted by nanoparticles attached at the end of the nanowires.3. Reacting of metal Ga with water vapor, we synthesized abundant well-crystallized β-Ga₂O₃ nanowires with narrow diameter-distribution. The crystal structure, the composition and the growth mechanism of the Ga₂O₃ nanowires were also intensively investigated. The contact properties of individual Ga₂O₃ nanowires with Pt or Au/Ti electrodes are studied respectively, finding that Pt can form Schottky-barrier junctions and Au/Ti is advantageous to fabricate Ohmic contacts with individual Ga₂O₃ nanowires. The conductivity of n-type semiconducting Ga₂O₃ nanowires is extremely sensitive to NH₃ or NO₂ even at room temperature.更多还原