在强磁场下采用共沉淀-相转化法制备出了纳米级的钴铁氧体颗粒，通过SEM，XRD和VSM等分析手段，考察了磁感应强度对纳米钴铁氧体形貌及性能的影响规律。试验结果表明：无磁场及磁感应强度小于2T时，纳米钴铁氧体颗粒为球形形貌；当磁感应强度大于等于4T时，有棒状纳米钴铁氧体形成；随着磁感应强度的增大，棒状纳米颗粒数量增加，纳米钴铁氧体的晶化程度提高，磁性能(Mr、Ms、Mr/Ms)也有大幅度的提高，10T时制备的纳米钴铁氧体颗粒的剩余磁化强度(Mr)比无磁场下制备的钴铁氧体颗粒的剩余磁化强度增加了近15倍，饱和磁化强度(Ms)提高1.44倍。从磁聚合定向生长和临界磁畴角度，分析了强磁场影响共沉淀-相转化法制备的纳米钴铁氧体的形貌、晶化程度及磁性能的机理。
Cobalt ferrite nanoparticles were synthesized in high static magnetic field by coprecipitation-phase transform way, and the influences of magnetic flux density(MFD) on the shape and properties of cobalt ferrite nanoparticles was studied through SEM, X-ray diffraction and Vibrating Sample Magnetometer. It was shown that, when without magnetic field or MFD lower than 2Tesla, spheric cobalt ferrite nanoparticles was obtained, and when MFD was equal or above 4Tesla, claviform cobalt ferrite nanoparticles appeared. With the increase of MFD, much claviform cobalt ferrite nanoparticles was obtained, and the crystallization of cobalt ferrite nanoparticles became better, also the magnetic properties such as remanence magnetism, saturation magnetism and squareness ratio were increased remarkably. The remanence magnetism of cobalt ferrite nanoparticles prepared in 10Tesla magnetic field was 15 times to that without magnetic field, and saturation magnetism was elevated by 1.44 times. Based on the theory of magnetic aggregation and critical magnetic domain, the mechanism how the high static magnetic field affect the shape, crystallization degree and magnetic properties of cobalt ferrite nanoparticles by coprecipitation-phase transform way was discussed.
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