尖晶石型纳米铁氧体是应用最广泛的磁性纳米材料之一。基于超顺磁和强磁响应这一对矛盾特性是制约该类型材料发展的关键瓶颈，本课题拟制备正、复合和反型三种具有代表性的尖晶石铁氧体，采用联合调控磁性的方法，即通过制备由小颗粒组装的纳米簇，在保持超顺磁的同时增强其磁响应；添加稀土离子，增强纳米簇的磁响应；应用表面活性剂有效调控金属离子在尖晶石结构中四面体和八面体间隙的分布，进一步提高纳米簇的磁响应。采用微量热技术原位测量纳米簇形成过程的热谱曲线，通过解析热谱曲线获知该过程经历的不同变化和相应的热动力学参数，并关联物相结构、形貌、磁性等表征技术，研究稀土离子对纳米簇磁性的影响，考察表面活性剂对金属离子分布的调控作用，探索在表面活性剂作用下尖晶石型铁氧体纳米簇磁性质的变化规律，揭示强磁响应的超顺磁纳米簇形成机理，为研制该类型纳米材料提供新思路、新方法和理论指导。

Nanosized spinel-style ferrites (MFe2O4 M = Zn, Mn, Co et al.) are often applied in various fields due to their chemical/magnetic stability and low cytotoxicity. However, a challenge is still found for the preparation of the ferrite showing superparamagnetic property and enhanced magnetic response. In order to solve this problem, three kinds of ferrites will be synthesized as the aiming samples through a solvothermal method, such as normal, mixed, and anormal ferrites. Clusters composed of nanosized ferrites will be first prepared, which show superparamagnetic property and enhanced magnetic response. Second, rare earth elements will be added into the clusters for improving their magnetic response. The content of the rare earth element will be obtained, which the saturation magnetization of the cluster reaches the highest. Third, different kinds of surfactants will be further used to enhance the magnetic response of the ferrite through modified occupation of cationic ions, where the content of the rare earth element keeps the same as that of the sample with the maximum saturation magnetization. A microcalorimeter will be used in situ to determine the power-time curve of the sample forming processes. Samples can be obtained at every forming process based on these curves. These samples are characterized by various technologies, such as XRD, FT-IR, ICP-AES, XPS, DSC, TG, SEM, TEM, HRTEM, VSM, SQUID, and Mössbauer. Effects of rare earth elements on magnetic property of the clusters and surfactants on occupation of cationic ions at tetrahedral and octahedral sites in the spinel structure will be studied. The formation mechanism of the nanosized clusters showing superparamagnetic property and enhanced magnetic response will be investigated by combining the characterized results and the thermokinetic parameters observed through analysis of the power-time curve. These results may be very useful to give new idea, and find novel method for the formation of the nanosized ferrite with superparamagnetic property and higher saturation magnetization.