【作者】 冯晋阳；

【导师】 赵修建；

【作者基本信息】 武汉理工大学 ， 材料学， 2008， 博士

【摘要】 纳米材料由于具有表面效应、体积效应、量子尺寸效应和宏观量子隧道效应,从而产生了许多奇异的力学、电学、磁学、热学、光学和化学等特性,因而受到广泛关注,对纳米材料制备与应用的研究已经成为材料科学研究领域备受关注的热点。金属纳米材料,尤其是贵金属金、银纳米颗粒的制备与研究一直是科技材料领域工作者研究的重点,有关金、银纳米金属颗粒的制备及性能的研究报导很多,但对于金、银纳米金属颗粒有序结构的制备与组装等方面的研究成果则很有限。另外,金属纳米颗粒所具有的表面等离子体共振使其具有了很好的光学特性。尤其近几年来,随着金、银等金属纳米颗粒的表面增强拉曼散射效应、以及荧光增强效应的进一步确认,对于金、银等金属纳米颗粒光学性能方面的研究已经成为纳米材料研究领域的一个热点。但是,这些研究主要集中在金属纳米颗粒的形貌、尺寸、发色团和局域场等方面,对于其有序纳米结构的光学性能方面的研究较少。基于上述国内外的研究现状,本论文从金属纳米有序结构的构建入手,对金、银纳米有序结构的制备进行了研究和探索,然后对所获得的金、银纳米有序结构的光学性能进行了研究,得到的主要研究成果包括以下几个方面:1.运用扩散理论和热力学基础理论,对拉伸还原技术中的结晶过程、还原反应过程进行了讨论;对玻璃拉伸中的形变进行了受力分析;结合具体的实验实现了有序银纳米颗粒在玻璃中的定向排布。微结构测试表明:玻璃样品中银颗粒呈长棒状,直径约50～100nm,长100～800nm,它们沿玻璃拉伸的方向呈定向排列。相应的工艺参数如下:晶化温度615℃,保温时间12h;拉伸温度570℃,拉伸速度120mm/min;还原压力0.25Mpa,还原温度430℃,还原时间4h。2.采用干法银离子置换-掩模板辅助照射技术,对在玻璃中可控生成有序纳米银簇进行了探索。获得了向玻璃基体中进行银离子注入的干法银离子置换的实验参数:电压1.5kV;温度350℃;时间150min。荧光光谱的研究表明,紫外光照射可以达到银的还原,并成为了卤化银结晶生成的晶核;偏振光透过光谱测试表明,经热处理和还原后玻璃中产生了银纳米簇有序化排布的结构迹象。3.依据米氏理论,对含有序纳米银颗粒玻璃的光学吸收性能进行了理论计算,并对具有不同微结构特征的样品进行了对比分析,结果显示:样品测试所得的偏光性能参数与理论计算基本一致;研究表明,样品的偏振波段带宽与样品中所含椭球形银颗粒的长径比分布状态有关,并随银颗粒的长径比分布范围增加而变宽。同时,研究表明玻璃中存在不同结构的Ag纳米颗粒,即针状的Ag颗粒和线状的Ag颗粒链,这些结构都对光的偏振效应有贡献。4.采用Z-扫描技术对含有序纳米银玻璃的三阶非线性光学性能进行了研究,结果表明:当入射光偏振方向与银纳米棒的轴向平行时,非线性折射率和非线性吸收系数均达到最大值。在入射光波波长为780nm,激光强度为1.9GW/cm²的条件下,且当光偏振方向与银纳米棒的轴向呈现垂直状态时,得到最佳的单光子品质因子W=1.6和最佳的双光子品质因子T=0.16,能够满足光开关应用所需的W＞1和T＜1的要求。5.利用二次阳极氧化法制备了平均孔径约为60nm、有序度较高的AAO模板。获得了超纯铝电化学抛光的磷酸-硫酸-乙二醇新体系的配方及工艺参数,新体系具有无污染、抛光效果良好的特点;得到了二次阳极氧化法中各工艺对AAO膜孔结构有序性影响的规律。6.利用AAO模板的有序孔结构,获得了金纳米颗粒的规则点阵,经吸收光谱测试表明,这种有序金纳米结构的可见紫外吸收峰位于536nm处,峰形尖锐,且与理想的球形金纳米颗粒的峰值位置一致。通过热处理载玻片表面镀制的掺金TiO₂溶胶,实现了金纳米颗粒的载持,对其光学性能研究中发现,该样品的可见紫外吸收峰产生了显著的红移,这主要归因于金纳米颗粒的等离子体共振吸收峰由于受到周围TiO₂颗粒的影响而产生红移所致。同时,该样品具有显著的荧光效应,在633nm处出现了很明显的荧光峰,这主要是由于金纳米颗粒的局域电场受到周围TiO₂颗粒的影响而产生改变所致。更多还原

【Abstract】 Nano-materials had many peculiar and fascinating properties in mechanics, electric magnetic,thermology,optics and chemical field,because of their basic properties of nanoparticles,such as surface effect,volume effect,quantum size effect and macroscopic quantum tunneling effect.The research and preparation of nanomaterials became a hot topic of the new times of science and technology.Reaearch on metal nano-materials,especially gold and silver metal nano-materials was always the focal point of scientists.There were many research reports about the controllable preparation and the assembly of gold and silver nanoparticles.However there were very limited results about the preparation and assembly of the ordered structure of gold and silver.For example,there were many reports on the preparation of glasses doped with gold and silver nanoprticles,but in these researches the nanoparticles only could be separated out on the surface or near the interface of block glass without spatial ordering.However,the ordered structure of gold and silver nanoparticles in the glass was necessary for opt-electronic integration,especially for all-optical integration technology.Moreover,metal nanomaterial had excellent optical properties due to the surface plasmon resonance.Especially in recent years,along with the confirmation of the surface enhanced Raman scattering effect and the fluorescence enhanced effect of gold and silver nanoparticles,the study of the performance and application of gold and silver nanoparticles had become a hot field of research.However,most research on the optical properties of it was focused on its morphology,size,fluorescein and emission field,while research on properties of the ordered structure of gold and silver nanoparticles was very limited.Basing on the current situation at home and abroad,the author firstly studied on the assembly of the ordered structure of gold and silver nanoparticles.After that,the optical properties of the ordered structure had been studied.The main results and conclusions of this dissertation were outlined as follows:1.With the diffusion theory and thermodynamics theory,the author had studied on the process of crystallization and reduction of the glass,and analyzed the stress of the glass during the stretching process.The ordered structure of silver nanoparticles arranged in the glass had been obtained.The microstructure of the glass samples was studied by FE-SEM.Silver nanorods had diameter of 50～100nm,length of 100～800nm.Corresponding technological parameters were outlined as follows:the heat treatment for crystallization was 615℃for 12h.The elongating temperature was 570℃.A stress of 75 kg was applied to the glass sample to draw at a rate of 120mm/min.The reduction was carried out at 430℃for 4h,and the hydrogen gas pressure was 0.25MPa.2.With the dry silver ion exchange and masking irradiation technology,the synthesis of silver cluster with ordered structure in the glass was studied.The experimental parameters of dry silver ion exchange were outlined as follows:1.5kV, 350℃,150min.The result showed that the silver ion could be injected into the glass by the dry silver ion exchange.The silver ion could be reduced and formed silver nucleus by UV irradiation.After the heat treatment and reduction,there was an indication of ordered arrangement of silver cluster formed in the glass.3.The optical absorption performance of the glass containing ordered structure of silver nanoparticles was calculated,contrastive analysis about the different structure of samples was done.The results showed that the polarizing performance parameters obtained from tests were consistent with the theoretical calculated results.The polarizing wavelength band of the glass sample was related to the distribution range of aspect ratio of the ellipsoid silver particles.Along with the increasing of distribution range,the band became broader.There should be two kinds of different configuration of silver nanoparticles involved in the polarization effect: one was the needle-like siver nanoparticles and another was the filament structure of silver.4.The third-order nonlinear optical properties of the glass samples were studied by Z-scan technology.The results showed that when the polarization of the laser was parallel to the elongation of the Ag nanorods,the nonlinear absorption coefficient and nonlinear refraction index reached their maximum values.At 780 nm,with a peak irradiance 1.9 GW/cm²,when the polarization of the light was perpendicular to the elongation of the Ag nanorods,the appropriate figures of merit W=1.6 and T=0.16 were obtained,which satisfied the requirement of W＞1 and T＜1 for all optical switching applications.5.By two-step anodization method,porous anodic alumina was prepared successfully,and the average diameter of the pores was about 60nm.The vitriol-phosphate-glycol system,which was adopted during the electrochemistry polishing of high purity aluminum patch,was studied.The factors that affect on ordered porous structure of AAO film were studied.The factors included the pretreatment technology,the oxidization voltage,duration time of secondary anodization and pore enlarging treatment.6.Au nanoparticles were loaded on porous alumina template surface by photoreduction technique,and spherical gold nanoparticles formed regular arrangement that was consistent with the pore structure of AAO.The UV-Vis optical absorption peak of the ordered structure of gold on the surface of AAO membrane was at 536nm,that was consistent with the absorption peak of the ideal sphere gold nanoparticles.By thermochemical reduction of titanium dioxide sol-gel system doped on glass substrate,sample of Au nanoparticles loaded on glass substrate was obtained. Test results showed that the optical absorption peak had a distinct red shift,this phenomena could be due to the change of the surface plasmons of Au nanoparticles caused by the TiO₂ crystal particles around it.Meanwhile,there was a distinct fluorescence emission at the wavelength of 633nm.With the contrastive analysis,the phenomena could be due to the change of the local electrical field of Au nanoparticles caused by the TiO₂ crystal particles around it.更多还原