【作者】 孙艳艳；

【导师】 姬广斌；

【作者基本信息】 南京航空航天大学 ， 物理化学， 2010， 硕士

【摘要】 铁氧体是世界上应用最早的磁性材料,因具有软磁、硬磁、矩磁、压磁等多种磁性能被广泛应用于磁记录材料、通讯、传感、军事等领域。本文对利用纳米铸塑法(又称硬模板法)和水热-熔盐法制备晶态钴铁氧体进行了探索,主要做了如下工作:(一)、基于纳米铸塑理论,以自制的两种介孔氧化硅SBA-15和KIT-6为硬模板,不添加任何络合剂,使低熔点的硝酸钴和硝酸铁在模板孔内分解,制备出介孔复合金属氧化物CoFe2O4。探究了浸渍方法及次数、模板与前驱体的配比等对产物结构的影响;优化实验条件,按金属前驱物与模板质量比为X=3经两步溶液浸渍制备出了大比表面积(以SBA-15为模板, 155.7 m2/g)、高结晶度的介孔钴铁氧体;并通过TG-DTA等分析,探究了氧化硅模板在钴铁氧体成相中的关键作用;测试结果表明样品具有良好的软磁性,矫顽力低至106.5Oe (以SBA-15为模板)。(二)、采用熔盐法晶体生长技术,以水热法制备的钴铁氧体纳米颗粒为前驱体制备出了大尺寸(0.5~1.5μm)、正八面体形貌的钴铁氧体晶体,探索了前驱体、反应温度、保温时间、熔盐种类及用量等因素对产物形貌的影响。实验得出:在NaCl/KCl体系中,以水热反应24样品为前驱体,当反应温度为1000oC、保温时间为5h、熔盐与前驱体质量比R=5,八面体形貌晶体产率较高,粒径较均匀;磁性、吸波性能分析表明产物的矫顽力、吸波性能较前驱体有所降低。更多还原

【Abstract】 Ferrites is a conventional magnetic materials, which has been widely used in many areas, such as message recording, communication, magnetc sensor, aviation etc. In this paper, two kinds of method have been used to prepare cobalt ferrite, the main work been done is as follows:Firstly, based on the nanocasting approach, large specific surface area, highly crystallined mesoporous CoFe2O4 were synthesized through the pyrolysis of hybrid metal nitrates within the pores of two kinds of mesoporous silica, SBA-15 and KIT-6, respectively. Impregnation process, mixture ratio of templates and precursors and other factors that may affect the structure of the product were investigated; samples with a large specific surface area (as high as 155.7 m2/g for the sample templated by SBA-15) and high crystallinity were obtained under optimized conditions, via two times of impregnation according to the mass ratio of precursors/templates X=3; TG-DTA and other characterization method revealed the important part that the silica templates played in the formation of cobalt ferrite phase; magnetic test revealed good magnetic properties of the mesoporous ferrite samples with a rather low coercitivity due to the presence of a prominent proportion of superparamagnetic particles.Secondly, molten salt has been reported to be an excellent media to prepare large crystals with special morphology. Via the molten salt synthesis (MSS) route, well defined octahedral CoFe2O4 crystals with the side length of about 0.5~1.5μm were obtained in a series of molten salt systems, using CoFe2O4 nano particles pre-synthesized through the hydrothermal process as the precursor. It was found that keeping the reaction temperature at 1000 oC for 5h and with a mass ratio of R=5 were the optimal conditions to prepare uniform octahedral ferrite crystals in NaCl/KCl system; furthermore, there were great changes in magnetic and wave-absorbing properties of the samples after molten salt growth, comparing with the precursor.更多还原