超顺磁性Fe_3O_4@SiO_2复合纳米粒子的制备、表征和性能研究

Preparation,Characterization and Properties of Superparamagnetism Fe_3O_4@SiO_2 Composite Nanoparticles

采用化学共沉淀法制备了超顺磁性Fe3O4纳米粒子,用改进的Stber方法在Fe3O4纳米粒子外面包覆一层SiO2。采用IR、XRD、SEM、PPMS等方法对Fe3O4纳米粒子和Fe3O4@SiO2复合纳米粒子进行了表征。分析研究了Fe3O4@SiO2复合纳米粒子的磁学性能和热稳定性。结果表明:Fe3O4@SiO2复合粒子比Fe3O4纳米粒子有更好的热稳定性和分散性。Fe3O4@SiO2复合粒子的饱和磁化强度(Ms)随着正硅酸乙酯(TEOS)浓度的升高而下降,随着氨水浓度的升高而先增加再减小,呈线性依赖关系。且Fe3O4纳米粒子在600℃热处理3h后已经完全转化为Fe2O3,复合粒子在800℃热处理后仍然只显示Fe3O4的物相。

Superparamagnetic Fe3O4 nanoparticles were prepared by chemical coprecipitation method,and a silica film was coated onto the surface of magnetite（ Fe3O4） nanoparticles through the modified Stber method. The Fe3O4 nanoparticles and Fe3O4@SiO2 composite nanoparticles were characterized by means of X-ray diffraction（ XRD）,fourier transform infrared spectra（ FTIR）,scanning electron microscope（ SEM） and physical property measurement system（ PPMS）. The magnetic properties and thermal stability of the composite nanoparticles were studied. The results show that the Fe3O4@SiO2 have better thermal stability and dispersion than the magnetite nanoparticles. The Msof Fe3O4@SiO2 composite nanoparticles decreases as TEOS concentration increasing,increases first and then decreases as ammonia concentration increasing. The Fe3O4 nanoparticles completely transform into Fe2O3 heated at 600 ℃ for 3h,and the composite particles are the Fe3O4 single phase after heating at 800 ℃.