用共沉淀法制备了Ni-Fe氧化物复合磁性纳米微粒，并采用Massart法合成了无表面活性剂的离子型磁性液体。用X射线衍射仪（XRD）、X射线能谱仪（EDX）、X射线光电子能谱仪（XPS）、透射电子显微镜（TEM）分别对其微粒结构及粒径进行分析，并用HH-15振动样品磁强计（VSM）测量了磁性微粒和磁性液体的磁化强度，分别用Langevin理论和类气压缩模型对磁性液体磁化曲线进行拟合。实验结果表明，Langevin理论曲线与实验曲线有较大偏差，而类气压缩模拟的曲线与实验曲线拟合的较好，且压缩参数γ随磁性液体体积分数的增大而增大。应用场致团聚效应解释了Ni2O3/γ-Fe2O3磁性液体的磁化性质。
Ni-Fe oxide composite magnetic nanoparticles prepared by chemical co-precipitation method are introduced and ionic ferrofluids without surface-active agent is made by Massart method. The microstructure and grain size are analyzed through XRD, EDX, XPS and TEM, and the magnetization vs. magnetic field is measured by vibrating sample magnetometer (VSM, HH-15). The magnetizing curves have been fitted by using Langevin theory and gas-like compression model, respectively. The results indicate that there is an obvious deviation between Langevin theory and experimental data while the gas-like compression model can fit well, and that the compression parameter γ increases with the increasing ferrofluids volume fraction. The magnetization behaviors of Ni2O3/γ-Fe2O3 ferrofluids can be well illustrated by the field induced aggregation effect.
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