【作者】 王艳荣；

【导师】 邱克辉； 邓昭平；

【作者基本信息】 成都理工大学 ， 材料学， 2004， 硕士

【摘要】 纳米粒子以其独特的光、声、电、磁、热、催化、力学、化学活性等性质及巨大的潜在的高科技前景，成为材料科学研究的热点之一，引起世界各国科学家的极大关注。 CeO₂是一种廉价、用途极广的轻稀土氧化物。与其它无机粉体一样，纳米化后的CeO₂产生一些新的性质和新的用途。但是，目前由于尚无成熟的制备方法和技术，使纳米CeO₂的制备和应用研究仍停留于实验室阶段，所以其合成研究是十分必要的。 本文简要介绍了我国CeO₂的资源和市场以及国内外纳米CeO₂的应用现状：分析对比了纳米CeO₂制备研究现状；重点讨论了沉淀法制备纳米粉体的理论基础：结合铈（Ⅲ）离子、铈（Ⅳ）离子的氧化—还原电位分析，提出以两步沉淀法来制备纳米二氧化铈。 试验的主要研究内容： （1）通过不同沉淀剂的制备研究，选择以硝酸铈、双氧水和氨水为基本原料，经过铈（Ⅲ）离子的氧化和铈（Ⅳ）离子的沉淀两个主要过程制备纳米二氧化铈。 （2）对纳米二氧化铈制备过程中可能的一些影响因素（反应组分的浓度，沉淀剂的加入量，焙烧温度，焙烧时间等）进行了研究，并通过TG—DTA分析手段对前驱物进行热重分析；用XRD、SEM及TEM等测试手段对产物的粒度和晶型进行分析；探索了各个因素对纳米二氧化铈制备的影响及各因素间的交互作用；确定了在该试验条件下制备纳米二氧化铈比较优化的制备条件。制备出粒度在10nm左右、分散性良好的纳米CeO₂。 （3）通过团聚机理和消除方法的分析，本试验采用高分子分散剂（PVA）和改变干燥方式的应用研究以提高所得产品的分散性。 （4）通过紫外—可见光光度计研究分析对比市售二氧化铈与纳米级二氧化铈紫外吸收性能。研究表明：纳米CeO₂有很好的紫外吸收性能。但是，目前还未见到将纳米二氧化铈应用于光降解方面的研究。本试验借助于721分光光度计对纳米二氧化铈的紫外吸收光降解性能进行了初步研究。更多还原

【Abstract】 Because of its many particular properties in optics , acoustics, electricity, magnetism, heat, catalysis, mechanics, chemical activity etc, and its great potential high technology applied prospects, nanopaticle has become one of the quite popular problem in materials research field, it gains much attention of the scientist from different countries in the world.CeO2 is a cheap and of use wide light rare earth oxide material. After it becomes nanoparticle,it will show some new properties and applications like other inorganic naoparticles.However.at present, because there aren’t is no sophisticated approaches and technologies that limit its development, the preparation of the CeO2 nanoparticles still stays the experimental stage. In conclusion, it is important to synthesize and application CeO2 nanoparticles because of its extensive use.This paper has reviewed the resources of CeO2 in our country, the markets and the condition of application. The advantages and drawbacks of the important preparation methods were reviewed. It puts emphasis on the reaction mechanism of precipitation method to nanoparticals and analyzes redox potential between Ce3+ and Ce4+, puts forward a new technics named "a two-stage precipitation process" to succeed in obtaining nanocrystalline powers of cerium oxide.The main contents of this dissertation are summarized as follows.(l)By investigating and preparing the CeO2 nanoparticles with various precipitators we choosed the cerium(III) nitrate, hydrogen peroxide and ammonia as the materials to prepared the nanoparticles by a two-stage precipitation method The process differents from the generalprecipitation process. The first stage is that Ce3+ is oxidized by hydrogen peroxide, and the second is that Ce4+ is precipitated by ammonium hydroxide.(2)The affecting factors such as components in precipitation process, the add-on, add on of precipitator, calination temperature and calination time were studied in the preparation process of CeO2 nanoparticles. The TG was used to analyze the processor, the XRD, SEM and TEM were used to characterize the size of crystal type of products. By a series of designed experiments the interaction between different factors and impacts on the preparation of CeO2 nanoparticles were probed, and the optimum preparation condition was gotten. The small particle sizes of lOnm and well dispersivity of CeO2 nanoparticles were gotten.(3)The Mechanism model of forming rigid agglomeration agglomeration and elimination methods were investigated, which are the critical problem in the preparation of ultrafine partical during liquid-phase process. The methods were employed such as the distributing agent PVA of macromolecule and changing the drying method to improving the dispersivity of CeO2 nanoparticles and overcome the problem of agglomeration.(4)The ultraviolet absorption character of CeO2 nanoparticles prepared in experiment and CeO2 microparticals sold in the market were analyzed and contrasted by ultraviolet radiation-visible light photometer. The investigation indicates that CeO2 nanoparticles prepared in experiment has the good ultraviolet absorption property. However, it is not found that CeO2 nanoparticles were employed at light degradation catalysis aspect. It is preliminary studied the ultraviolet absorption character of CeO2 nanoparticles were used for degrading helianthine with the help of the 721-type spectrophotometer.更多还原