【作者】 王莉；

【导师】 张新荣； 朱永法；

【作者基本信息】 清华大学 ， 化学， 2004， 博士

【摘要】 纳米技术是21世纪最前沿的科研领域之一,而纳米材料和纳米结构则是纳米科技中的重要组成部分。基于纳米结构对纳米材料性质的影响,本文分别制备了碱土金属铝酸盐纳米颗粒、碳酸盐纳米线和非化学计量比碱土金属铝酸盐多孔纳米球,并研究了纳米结构对材料光学和催化性质的影响。本论文获得的主要成果如下:1、利用非晶态络合物法在温度低于传统方法500℃条件下获得了物相纯正的尖晶石结构SrAl2O4和BaAl2O4纳米粉体,成功实现了高温纳米材料的低温合成,而且该种方法制备的纳米粉体在1000℃下仍具有很好的稳定性;2、研究发现SrAl2O4 和BaAl2O4纳米粉体在还原前后虽然粉体的组成、结构和形貌没有发生明显变化,但出现了在紫外-可见-近红外全波段吸收的特性,初步研究表明该光学特性同纳米粉体中的氧缺陷浓度有关;3、采用气-液界面反应法制备了均匀的长径比大于1000的SrCO3和BaCO3纳米线,并根据纳米线的形成过程及其影响因素提出了“优势生长→自组装→结构重组”的纳米线生长机理;4、研究发现纳米结构对材料的催化性能具有显著影响。实验结果表明,SrCO3纳米线的活性明显高于SrCO3纳米颗粒,进一步研究发现两种纳米结构催化剂的表面活性中心的分布也具有明显差异;5、利用SrAl2O4 和BaAl2O4纳米粉体在乙醇溶液中的水解反应,成功制备了直径40-100 nm的MAl4O7(M=Sr,Ba)介孔纳米球,并发现通过调节乙醇浓度、加热方式和加热时间可以实现对纳米球内部结构的有效调控,在此基础上,提出了“颗粒模板-原位反应”的纳米球形成机理。更多还原

【Abstract】 Nano-science and technology is one of the most advanced research fields in 21th century, and the investigations on nano-materials and nano-structures are of particular importance. On the basis of the significant effects of nano-structure on nano-materials’ properties, the interest of this dissertation is focused on preparation and property investigation of nano-materials. MAl2O4 nano-particle, MCO3 nano-wire and MAl4O7 nano-sphere (M = Sr or Ba) were fabricated successfully. The relationship between nano-structure and property has also been investigated in detail. In general, novel preparation methods and some new properties were provided to synthesis and application of these nano-materials. The main contents of this report are as follows:Using amorphous hetero-nuclear complexes as precursors, pure spinel SrAl2O4 and BaAl2O4 nano-particles were successfully synthesized at low calcinations temperature, which was about 500℃ lower than that in conventional methods. Nano-structure of these nano-particles showed high stability even at 1000℃, indicating that high-temperature materials can be easily prepared at a relatively low temperature by this method.The investigation indicates that nano-structure has great effect on the optical property of SrAl2O4 and BaAl2O4. A simple reduction process can make these nano-particles show uniform adsorption throughout UV-VIS-NIR, in spite that their composition, crystal structure and morphology did not change after this process. Further study indicates that the unique optic performance is related to the concentration of oxygen vacancy in nano-particles.Uniform SrCO3 and BaCO3 nano-wires with high aspect ratio of over 1000 were successfully prepared using a simple gas-liquid reaction. And a formation mechanism described as “preferentially growth→self-assemble→restructure” has been proposed. It has been found in this work that one-dimensional structure has great effect on the catalytic property of nano-materials. The activation temperature of formaldehyde <WP=6>and ethanol decreased 230℃-300℃ when catalyzed by SrCO3 nano-wires. Our results showed that nano-wires had obviously higher catalytic activity than nano-particles, and such an improvement in the catalytic activity could be attributed to the different distribution of active centers on nano-wires and nano-particles.MAl4O7 (M = Sr,Ba) porous nano-spheres were successfully prepared by hydrolyzing of SrAl2O4 and BaAl2O4 nano-powder in ethanol-H2O solution, and the interior structure of these nano-spheres can be easily prepared by controlling concentration, heating mode and heating time. Based on the results obtained above, a formation mechanism described as “template-in situ reaction” was proposed.更多还原