反相微乳液法制备超顺磁性核壳Fe_3O_4@SiO_2纳米颗粒

Preparation of Superparamagnetic Core-Shell Fe_3O_4@SiO_2 Nanoparticles by Reverse Microemulsion

分别用一步法和两步法在Tritonx-100/正己醇/环己烷/水反相微乳液体系中,以纳米Fe_3O_4粒子为核,利用正硅酸乙酯在碱性条件下水解制备纳米Fe_3O_4@SiO_2纳米颗粒。通过XRD、FT-IR、SEM、TEM和VSM对复合颗粒的晶体结构、结合状态、表面形貌、微观特征和磁学特性进行了表征。结果表明,2种方法制备的Fe_3O_4核均为尖晶石结构,SiO_2壳均为无定形结构;复合颗粒呈球形,且团聚在一起;相比较而言,一步法分散性较两步法要好;两者都具有超顺磁性,在室温、外场为1T时磁化强度分别为23emu/g、11emu/g。

One-step and two-step methods are used to prepare silica-coated magnetic nanoparticles（Fe3O4@SiO2 ）. In both methods, the Fe3（h nanoparticles are used as seeds to prepare Fe3O4@SiO2 nanaoparticles in the Triton X-100/hexanol/cyclohexane/water reverse microemulsion system via hydrolysis of tetraethyl orthosilicate（TEOS） under basic condition. The structural, morphologival, and magnetic properties of the coated nanoparticles are then characterized by XRD, FT-IR,SEM,TEM,and VSM. The results show that the structure of the Fe3O4 core is spinel structure, the SiO2 shell is amorphous, they both exhibit spherical morphologies and the nano-spherical particles form clusters. Compared with the two-step method, the particles that are made by one-step method show better dispersivity. The two kinds of coated particles all have superparamagnetic behavior. Their magnetization are 23emu/g and 11emu/g respectively, with an additional magnetic field of IT at room temperature.