强磁性Fe_3O_4纳米粒子的制备及其性能表征

Preparation and Characterization of Nano-size Fep_3O_4 Particles with Strong Magnetism

采用共沉淀法在无N2气保护下制备了比饱和磁化强度达到75 9emu g的强磁性Fe3O4纳米粒子。在用NaOH溶液沉淀Fe3+和Fe2+混合溶液的过程中,考察了n(Fe2+)∶n(Fe3+)、晶化时间、晶化温度、总铁浓度和NaOH溶液浓度等条件对Fe3O4纳米粒子的粒径分布及磁性的影响。当n(Fe2+)∶n(Fe3+)=5 5∶1 0,晶化时间为2h,晶化温度为50℃时,Fe3O4纳米粒子磁性最佳。所制得的Fe3O4粒子为结晶完整、具有较高纯度和粒径分布均匀的立方体形纳米颗粒;其相变温度随着Fe3O4纳米粒子粒径的减小而降低。Fe3O4纳米粒子的等电点约为pH=7 2。

Nanosize Fe3O4 particles with strong magnetism (σs=759 emu/g) were prepared by coprecipitation of Fe2+ and Fe3+ with aqueous NaOH solution.The results indicate that the size and magnetism of the Fe3O4 particles can be effectively controlled by changing the conditions of preparetion.Nanosize Fe3O4 particles with strongest magnetism are synthesized under the optimum conditions of n(Fe2+)∶n(Fe3+) 55∶1,aging time 2 h and aging temperature 50 ℃.The Fe3O4 particles obtained are wellcrystallized cubic particles with high purity and narrow particle size distribution.The phase transfer temperature of nanosize Fe3O4 particles decreased noticeably with decreasing particle size.The isoelectric point (IEP) of nanosize Fe3O4 particles is at pH=72.