【作者】 刘淑贞；

【导师】 钱逸泰；

【作者基本信息】 中国科学技术大学 ， 无机化学， 2010， 博士

【摘要】 本论文旨在探索和研究微尺度(微米～纳米)金属硫化物半导体材料,如PbS、CuS、Ni3S2、NiS、ZnS等,在生物小分子辅助下获得具有特殊形貌和结构的半导体纳米材料,系统研究结构、形貌、尺寸和性能之间的关系,根据试验结果提出了其可能的生长机理,探讨了它们的光学性质,从而获得一些制备自组装微纳米材料的规律。我们以PbS、Cus、Ni3S2、NiS、ZnS为例,通过改变反应条件,如反应物的摩尔比、混合溶剂的体积比、反应温度、反应时间等,有效地控制了产物的形貌。本论文的主要研究内容包括以下三个部分：1.丰富和发展了生物小分子辅助法和溶剂热合成技术。在乙醇胺—水混合溶剂体系中,由L-蛋氨酸分子辅助及参与反应,控制合成了不同形貌的PbS微米晶体。通过改变反应温度、乙醇胺／水的体积比及反应物的摩尔比,有效控制了产物的形貌。研究了鱼骨状结构的PbS枝晶的光学性质(光致发光光谱),中心位于423 nm处有一个强的蓝光发射峰。同时,根据实验结果,我们提出了鱼骨状枝晶的PbS微米晶体的可能的生长机理是先成核后生长的过程。该工作对于选择合适的生物小分子(既能做结构导向剂,又能做硫源),实现IV-VI族金属硫化物半导体微纳米材料的形貌控制方面具有一定的指导意义。该研究结果发表在The Journal of Physical Chemistry C (2009,113,13002)上2.设计出乙醇-水反应体系,在此体系中,合成了由纳米颗粒自组装而成的微米实心立方块结构的CuS晶体,据我们所知,CuS的这种立方块状结构非常新颖,还是首次得到。实验表明,乙醇／水的体积比,对产物的形貌有很大的影响。研究了实心立方块结构的CuS晶体的紫外-可见吸收光谱,在675 nm处有一个宽的吸收峰,与文献中的结果相比,有了显著的红移,这种不寻常现象在光学领域有应用的潜力。根据实验结果,我们提出了先成核后生长的由纳米颗粒构成的CuS微米实心立方块的可能的形成机理。3.我们用L-蛋氨酸这种生物小分子既作为结构导向剂,又作为硫源,在乙醇胺-水的混合溶剂中控制合成了不同物相和形貌的各种硫化镍微米晶体和硫化锌微米晶体。系统研究了不同反应条件对产物物相和形貌的影响。例如,通过控制原料Ni(Ac)2-7H2O和L-蛋氨酸的摩尔比从1：2变化到1：1,我们可以得到Ni3S2(由纳米颗粒组装而成的呈现放射状的微米球)和NiS(表面有棱的微米管及由小棒组装成的花状结构)这两种不同物相和形貌的硫化镍微米晶体。通过调节乙醇胺／水组成的混合溶剂的体积比,我们制备了不同形貌的纤锌矿(花状结构和类似于球的结构基元构成的链状结构)；当溶剂改为NH3·H20和水组成的混合溶剂、其他反应条件保持不变时,我们得到了闪锌矿的硫化锌(由纳米片组装成的微米球)。研究了不同结构和形貌的硫化锌的发光性能。根据实验结果,我们提出了Ni3S2(由纳米颗粒组装而成的呈现放射状的微米球)的可能的形成机理。该工作对于选择合适的条件来实现硫化物半导体微纳米材料的物相和形貌的控制合成方面具有一定的指导意义。更多还原

【Abstract】 The goal of this dissertation is to explore and study semiconductor metal sulphides micro and nano-scale materials such as PbS, CuS, Ni3S2, NiS, ZnS with special structures and novel morphologies via the assistance of L-methionine, and is to investigate the relationship among their structures, morphologies, sized and capabilities. Based on the experimental results, a possible growth mechanism was proposed to explain the formation of the as-synthesized architectures. And the optical properties of the obtained products were also studied. According to the results, some kinds of rules were drawn to synthesize micro and nano-scale materials which are self-assembled. Taking semiconductor metal sulphides such as PbS, CuS, Ni3S2, NiS, ZnS for example, by adjusting the reaction parameters, such as the molar ratio of the reactants, the volume ratio of the mixed solvents, the reaction temperature, the reaction time, the crystal structure and the morphology of the products can be effectively controlled.The main contents of the dissertation can be summarized as follows:1. PbS fishbone-like architectures were synthesized by using a biomolecule (L-methionine)-assisted approach in a mixture solvent made of ethanolamine (EA) and distilled water. Additionally, other PbS homogeneous morphologies (e.g., hexapod-like, coralloid, dendritic) were obtained through altering the experimental parameters, such as the molar ratio of the reactants, the volume ratio of ethanolamine (EA) and distilled water. Meanwhile, the optical properties of the as-synthesized PbS fishbone-like architectures were characterized by photoluminescence spectrum at room-temperature and a strong blue light peak centered at a wavelength of 423 nm is observed. Simultaneously, according to the experimental results, a possible growth mechanism was proposed to explain the formation of PbS fishbone-like architectures. The present work proves thatⅣ-Ⅳsemiconductor micro-or nanocrystals with controlled phase and morphology can be achieved via solvothermal route by selecting some appropriate biomolecule which acts as not only structure-directing agent but also sulfur source. The above results of research have been published in Journal of Physical Chemistry C.2. A reaction solution made of absolute ethanol and distilled water was developed to synthesize CuS micrometer-sized solid cubes which were composed of close-ordered nanoparticles via a biomolecule (L-methionine)-assisted approach. To our best knowledge, it is for the first time that the morphology of CuS cubes is obtained. Based on the experimental results, the volume ratio of absolute ethanol and distilled water played a key role on the morphology of the products. The optical properties of CuS cubes were investigated by UV-vis absorption and a broad absorption peak centered at a wavelength of 675 nm is observed, and the unusual phenomena may have potential applications in the optical field.3. Nickel sulphides microcrystals and zinc sulphides microcrystals (including wurtzite and zinc blende) with tunable phase and morphology were synthesized by using L-methionine molecule as structure-directing agent and sulfur source in a mixture solvent made of ethanolamine (EA) and distilled water. It was found that the phase and the morphology of nickel sulphides could be controlled by adjusting the Ni/S ratio of the reactants, that the phase and the morphology of zinc sulphides could be controlled by changing the solvent. For instance, with the molar ratio of Zn(Ac)2-2H2O to L-methionine increasing from 1:2 to 1.5:1, Ni3S2 microspheres composed of nanoparticales and NiS microtubes with several edges on the surface and NiS complex microflower-like structures can be successively obtained. By adjusting the volume ratio of ethanolamine (EA) and distilled water, various morphologies of wurtzite ZnS were obtained (microflower-like structure and a chain of semi-spheres). When the mixture solvent was replaced by NH3-H2O and distilled water, microspheres-shaped blende zinc ZnS were obtained. Meanwhile, the optical properties of ZnS with different phase and morphology were investigated by photoluminescence spectrum. According to the experimental results, a possible growth mechanism was proposed to explain the formation of Ni3S2 sphere-like architectures.更多还原