中文摘要：

以溶剂热法制备的高磁饱和强度 Fe3O4纳米颗粒为核，正硅酸乙酯（TEOS）为前驱体，采用 St？ber 方法，在乙醇/水溶液中，通过氨水催化水解硅醇盐，制得核壳结构的 Fe3O4/SiO2复合磁性微球。对制备的样品的物相结构、形貌和磁性能进行了测试表征。结果表明：制备的 Fe3O4/SiO2磁性微球呈球形，粒径分布均一，SiO2壳层圆整光滑，厚度为40～70 nm。X 射线衍射分析显示，Fe3O4/SiO2磁性微球具有尖锐的 Fe3O4特征衍射峰，表明包覆过程没有破坏 Fe3O4的晶体结构，其室温下的磁滞回线呈顺磁性,且比饱和磁化强度为30 A·m2/kg。此外，对 SiO2壳层的包覆机理进行了探究。

英文摘要：

The Fe3O4/SiO2 magnetic core-shell composite microspheres were synthesized via the hydrolysis of silicon alkoxides catalyzed by ammonia in ethanol/water solution by a modified St-ber method with Fe3O4 nanoparticles as cores synthesized using tetraethyl orthosilicate （TEOS） as a precursor by a solvothermal method. The morphology, structure and magnetic properties of Fe3O4/SiO2 magnetic composite microspheres were characterized. The results show that the as-prepared Fe3O4/SiO2 magnetic microspheres exhibit a spherical shape and uniform particle size distribution. Moreover, SiO2 shells are round and smooth and their thickness is around 40-70 nm. According to the analysis by X-ray diffraction, Fe3O4/SiO2 magnetic microspheres possess sharp Fe3O4 characteristic diffraction peaks, indicating that the coating process does not destroy the crystal structure of Fe3O4. The hysteresis loop exhibits its superparamagnetism at room temperature and a specific saturation magnetization intensity of 30 A·m2/kg. In addition, the mechanism of coating SiO2 shell was also discussed.