【作者】 陈东；

【导师】 李家俊；

【作者基本信息】 天津大学 ， 材料学， 2008， 博士

【摘要】 Fe、Ni金属纳米粒子具有磁性金属微粉材料、纳米金属材料和纳米磁性材料的多种优点;核壳型Ni/Au磁性金属纳米粒子作为一种新型的复合纳米功能材料在生物医学等领域有着广阔的应用前景。由于传统制备方法的限制,纳米粒子往往存在粒度分布不均、分散性差等问题,且无法对纳米粒子的微观形貌做到精细控制。反相微乳液体系为纳米材料的可控制备提供了新的可能。本论文通过在反相微乳液体系中还原Fe、Ni金属盐的方法制备Fe、Ni纳米粒子,研究了Ni金属盐溶液与乳化剂的配比对纳米粒子粒径的影响,并通过改变这一配比制备了具有不同粒径大小,且单分散的Ni纳米粒子。在此基础上,利用氧化还原-转移金属化反应制备了具有核壳结构的Ni/Au磁性金属纳米粒子,研究了用于制备核壳型纳米粒子的Ni粒子粒径和体系中的氯金酸加入量对Ni核粒径和Au壳层厚度的影响,并通过采用具有不同粒径的Ni金属纳米粒子和控制产氯金酸加入量的方法,实现了对Ni核粒径和Au壳层厚度的控制。本研究制备的Fe、Ni、核壳型Ni/Au磁性金属纳米粒子完全由Fe、Ni和Au构成,不含有其它杂质。对于核壳型Ni/Au磁性金属纳米粒子,包裹Ni核的Au壳层可以有效地减缓Ni核的氧化速度。核壳型Ni/Au磁性金属纳米粒子的截止温度随着Ni核的减小从53 K降低到16 K。在截止温度以下,纳米粒子表现出铁磁性;在截止温度以上,纳米粒子表现出理想的超顺磁性。此外,通过反相微乳液法合成了一种可作为催化剂前驱体的Ni基类水滑石化合物,研究了乳化剂类型对制备过程的影响,发现采用由阴离子乳化剂和非离子乳化剂体系组成的混合型乳化剂体系可以制得理想的纳米级水滑石化合物。与传统的共沉淀制备法相比,通过反相微乳液法制备的催化剂具有更小的Ni晶粒,更好的热稳定性,更高的比表面和Ni金属分散度,而且,Ni颗粒在载体中也分散得更加均匀。更多还原

【Abstract】 Fe and Ni nanoparticles possess the merits of magnetic metal fine powders, nanometer metals, and nanometer magnetic materials. As a new kind of nanometer functional composite materials, core/shell Ni/Au nanoparticles have broad applications in biomedical field. However, due to the limitations of the traditional preparation methods, it is difficult to get nanoparticles with uniform diameters, and to control the morphology elaborately. Reverse microemulsion provids a new possible method to resolve these problems.In this work, Fe2+, Ni2+ cations were reduced in the reverse microemulsionsystem to prepare Fe, Ni nanoparticles, and the relations between the Ni nanoparticle diameters and the ratios of Ni2+ solution to emulsifier were investigated. On this basis, core/shell Ni/Au nanoparticles were prepared through a redox-transmetalation method, and the diameters of Ni nanoparticles, the amount of added HAuCl4 which affected the morphology of core/shell Ni/Au nanoparticles was discussed. The morphology was found determined by these factors. The Fe, Ni, and core/shell Ni/Au nanoparticles prepared in this work was pure, without any impurities. For core/shell Ni/Au nanoparticles, the gold shells could effectively slow down the oxidation of the Ni cores. The block temperature of the core/shell Ni/Au nanoparticles decreased from 53K to 16K, with the decreasing of the Ni cores. When the temperature below the block temperature, the sample was ferromagnetic, while above the temperature the sample was superparamagnetic.In addition, Ni-based hydrotalcite-like compounds was synthesized through the reverse microemulsion method, which could be used as catalyst precursor. The type of emulsifiers which could affect the synthesis process was investigated. The mixture of anion emulsifier and cation emulsifier were able to provide a proper system for the syntheis of hydrotalcite-like compounds. Compared with the conventional coprecipitation method, the catalyst obtained from reverse microemulsion exhibited finer Ni crystal grains, higher specific surface, better thermal stability, and uniform dispersion.更多还原