【作者】 张辉；

【导师】 阙端麟； 杨德仁；

【作者基本信息】 浙江大学 ， 材料物理与化学， 2005， 博士

【摘要】 自1991年Iijima合成纳米碳管以来,一维纳米材料由于其新颖的物理、化学和生物学特性以及在纳米器件中的潜在用途成为当今纳米技术的研究热点。而一维纳米材料大量、低成本和简单有效地合成与组装无论从基础研究的角度,还是从性能与应用的角度来看,都有着特殊重要的意义。 本文主要利用化学溶液法制备多种材料的准一维纳米结构,系统地研究了各种生长条件对纳米材料形貌、尺寸、结构和性能的影响,并探索它们的形成机理,最后对ZnO准一维纳米结构做了初步的应用研究。论文的主要创新性结果如下: （1） 提出了巯基乙酸（TGA）辅助水热法合成硫化物准一维纳米材料的新方法,该技术具有简单、有效、成本低、产量大和环保等优点。利用此方法,合成了如下准一维纳米结构:六方相CdS单晶纳米棒和多晶纳米棒束;单斜相CdS多晶纳米带、纳米管和纳米纤维;正交相Bi₂S₃超长单晶纳米线和纳米花;正交相FeS单晶纳米棒;六方相SnS₂单晶纳米带以及立方相PbS单晶纳米棒等,从而证明此方法在制备硫化物准一维纳米材料方面具有普适性。系统研究了TGA辅助水热法的各种条件如:时间、先驱体溶液配比、温度、TGA、升温速率、硫源以及有机物添加剂对硫化物准一维纳米材料的形貌、大小和结构的影响。对由TGA辅助水热法制备的硫化镉纳米棒光学性质的研究表明,CdS纳米棒有三个光致发光峰,其中398nm属于TGA和CdS纳米棒络合体的发射峰;485nm属于硫化镉带间跃迁发射峰,和块体CdS相比有明显的蓝移;580nm属于硫化镉中深能级缺陷的发射峰。上述三个发射峰的叠加而形成的峰位大约在440nm左右,从而阐明了许多文献中观察到的硫化镉纳米棒的发射峰小于其吸收峰的原因是硫化镉纳米棒表面存在络合体,而非文献中提出的量子效应。 （2） 合成和发现硫化镉的亚稳新相。利用TGA辅助水热法,在低温下（100～160℃）合成了一种硫化镉的亚稳新相一单斜相,经过初步分析得到了它们的晶体学参数。研究表明:当温度高于350℃,硫化镉单斜相将首先转变为立方相,然后变成六方相。紫外可见吸收光谱表明:单斜相硫化镉禁带宽度较约为2.7eV。 （3） 提出利用准一维氧化物纳米材料为模板,结合TGA辅助水热法中的硫代反应以及后续的酸或者碱处理,合成非层状硫化物纳米管及氧化物/硫化物核壳纳米结构的新方法。该方法具有简单、有效、成本低、产量大和普遍等优点。利用此方法我们制备了ZnS纳米管以及ZnO/ZnS核壳纳米结构、SnS₂纳米管以及SnO₂/SnS₂核壳纳米结构、MnO₂/MnS₂核壳纳米结构。此外,利用阵列化的氧化锌纳米棒,衍生出阵列化的ZnS纳米管以及ZnO/ZnS核壳纳米结构。从而证明此方浙江人学博_{学位论文法可以制备各种硫化物纳米管及氧化物/硫化物核壳纳米结构。 （4）首次制备了硒纳米管。研究指出,利用水热和声化学相结合的力一法,通过控制水热时间和溶剂的种类,实现了硒纳米线和纳米管的可控制备。机理研究表明,形成硒纳米管还是纳米线是由结晶硒球的破裂与否决定的,大尺寸结晶硒球的破裂是硒纳米管的形成原因,而小尺寸硒球的定向连接是硒纳米线的形成原因。从硒纳米线和纳米管的形成机理、超声波能量的传输以及溶剂的性质（如表面张力、粘度、海森参数）出发,推导出硒纳米线和纳米管的形成条件及其经验判据。利用相似原理,我们把上述方法应用到蹄准一维纳米结构的制备中。研究表明:通过使用不同的溶剂可以实现筛纳米线和纳米管的可控制备,并发现不同于硒准一维纳米结构的形成机理。结合筛纳米线和纳米管的形成机理以及溶剂的性质推导出形成蹄纳米线还是纳米管的经验判据。 （5）利用十六烷基三甲基嗅化氨（CTAB）辅助水热法,首先在较低温下（如120℃）制备了氧化锌的纳米棒花。论文还系统地研究了水热法中各种影响因素对氧化锌纳米结构形成的影响。研究表明:在纯水热法中,提高温度和pH值可促进氧化锌的各向异性生长。利用不同的包裹分子如氨水、柠檬酸和聚乙烯醇可以对氧化锌纳米结构进行裁剪。对ZnO纳米结构形成机理的研究表明:所有氧化锌纳米结构的形成都符合极性生长理论,其生长基元是zn（oH）’]2一,各种生长条件对氧化锌纳米结构的影响主要是通过控制氧化锌核心和生长基元在先驱体溶液中的比例以及氧化锌核心的大小来实现的。在氧化锌圆盘、哑铃纳米结构和纳米棒花的光致发光谱中只存在和带间跃迁相关的发射峰,而在氧化锌纳米花的PL谱中除了存在和带间跃迁相关的发射峰外,还有和氧空位相关的发射峰。 （6）发现了溶液法制备阵列化氧化锌的二次生长现象,制备了场发射原型器件和电容式湿度传感器。该方法制备的氧化锌纳米棒具有产量大、直径细小和均匀等优点。溶液浓度的降低和由外向内的生长规律是形成双层阵列化氧化锌纳米棒的原因。对阵列化氧化锌纳米棒的场发射和湿敏性能研究表明:直径小的氧化锌阵列的场发射性能较好,其中直径为3Onm的氧化锌阵列的开启场强为ZV/pm,门槛场强为SV/pm。基于直径为30nln的氧化锌纳米棒阵列的电容式湿度传感器,其阻抗随环境湿度的增大而快速减少,阻抗与相对湿度近似成线性关系,并且湿滞回差小于10%RH,显示出较好的湿敏特性。 此外,论文还利用氧化铝模板辅助化学?更多还原

【Abstract】 Since the discovery of carbon nanotubes in early 1990’s, quasi one-dimensional nanomaterials have received intensive interests due to their novel physical, chemical, and biological properties as well as the potential applications in nanodevices. Large-scale, cost-effective, simple and practical synthesis and assembly of one-dimensional nanomaterials is of importance for the fundamental research and application.In the dissertation, the quasi one-dimensional nanostructures of a variety of functional materials have been synthesized by chemical solution routes. The effects of synthetic conditions on the morphology, size, structure and properties of the nanomaterials have been systematically investigated. Moreover, the formation mechanisms of the as synthesized nanostructures have been elucidated. Finally, the application of ZnO nanostructures has been preliminarily addressed. The significant results achieved in this dissertation are given as below:(1) The quasi one-dimensional nanomaterials of sulfides have been fabricated by a novel thioglycolic acid (TGA) assisted hydrothermal method. Compared to previous method, it has simple, practical, cost-effective, large-scale and environment-friendly advantages. The quasi one-dimensional nanostructures of sulfides prepared by this method include: single crystalline hexagonal CdS nanorods and polycrystalline nanorod bundles; polycrystalline monoclinic CdS nanobelts, nanotubes and nanfibers; single crystalline tetragonal Bi2S3 ultra-long nanowires and nanoflowers; single crystalline tetragonal FeS nanorods; single crystalline hexagonal SnS2 nanobelts and single crystalline cubic PbS nanorods. It has been well proved that the TGA-assisted hydrothermal method is extensively applicable in the synthesis of one-dimensional nanomaterials of sulfides.The effects of synthetic conditions of the TGA-assisted hydrothermal process including the time, constituents of precursor solution, temperature, TGA, temperature ramping rate, sulfur source and organic additive, etc. on the morphology, size and structure of the one-dimensional sulfide nanomaterials have been investigated. The investigation of optical properties of CdS nanorods prepared by the TGA-assisted hydrothermal process indicates that there are three photoluminescence (PL) bands of CdS nanorods at 398, 485, and 580 nm, respectively. Among them, the PL band at 398 nm originates from the emission of the complex of CdS nanorods, and the PL band at 485 nm arises from the band to band emission, which is blueshifted in comparison to that of the bulk CdS, while the PL band at 580 nm is resulted from the deep-level withinthe bandgap of CdS. The superimposition of the above-mentioned three bands leads to a wide band at 440nm, which accounts for the reason that the peak wavelength of PL emission band is shorter than that of absorption band is not quantum size effect but the existence of the complex clusters in the surface of CdS nanorods.(2) A new sub-phase of CdS has been fabricated. The monoclinic CdS has been derived by the TGA-assisted hydrothermal process at low temperatures of 100-160 ℃ . Preliminary study of X-ray diffraction (XRD) pattern results in their crystallographic parameters. The further study indicates that the monoclinic phase of CdS can firstly be transformed into the cubic phase and then into the hexagonal phase when annealed at temperatures larger than 350℃. The ultra-violet absorption spectra (UV-vis) reveal that the bandgap of the monoclinic CdS is about 2.7eV.(3) A novel route to the synthesis of sulfide nanotubes and oxide/ sulfide core-shell nanostructures derive from one-dimensional oxide nanomaterials by the sulfuration reaction during the TGA-assisted hydrothermal process and the subsequent acid or alkali treatment has been presented. Compared to previous methods, it has simple, practical, cost-effective, large-scale and extensively applicable advantages. Based on this route, ZnS nanotubes, ZnO/ZnS core-shell nanostructures, SnS2 nanotubes, SnO2/SnS2 core-shell nanostructures, and MnO2/MnS更多还原