Abstract MFe2O4 nanoparticles with M = Fe, Co and Ni were prepared by three different methods (coprecipitation, sol-gel and hydrothermal synthesis). XRD patterns reveal an increase in the unit cell parameter associated to the presence of Fe2+. More intense diffraction maxima are observed for samples prepared by sol-gel. Particle size appears to be larger for Co ferrites and sol-gel samples. By contrast, smaller grain sizes are observed for NiFe2O4 and hydrothermal samples. The highest Ms appears in the Fe3O4 obtained by coprecipitation. An increment in the saturation magnetization values is found in the cobalt and nickel samples prepared by hydrothermal method. Iron and nickel samples behave as superparamagnetic materials with low blocking temperatures while CoFe2O4 samples exhibit a characteristic ferrimagnetism. Variations observed in the ZFC/FC curves of coprecipitation-prepared samples are related to both the different particle size distribution and the values of magnetic anisotropy constant.

中文翻译：

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不同合成路线制备的MFe2O4纳米粉体的结构、形态和磁性对比研究

摘要 通过三种不同的方法（共沉淀、溶胶-凝胶和水热合成）制备了 M = Fe、Co 和 Ni 的 MFe2O4 纳米粒子。XRD 图显示与 Fe2+ 存在相关的晶胞参数增加。对于通过溶胶-凝胶制备的样品，观察到更强烈的衍射最大值。Co 铁氧体和溶胶-凝胶样品的粒径似乎更大。相比之下，NiFe2O4 和热液样品的晶粒尺寸较小。最高的 Ms 出现在通过共沉淀获得的 Fe3O4 中。在通过水热法制备的钴和镍样品中发现饱和磁化值增加。铁和镍样品表现为具有低阻塞温度的超顺磁性材料，而 CoFe2O4 样品则表现出特有的亚铁磁性。