Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.
Nanoscale. 2011 Feb;3(2):701-5. doi: 10.1039/c0nr00497a. Epub 2010 Nov 19.
Silica coated magnetite (Fe3O4@SiO2) core-shell nanoparticles (NPs) with controlled silica shell thicknesses were prepared by a modified Stöber method using 20 nm hydrophilic Fe3O4 NPs as seeds. The core-shell NPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected area electron diffraction (SAED), and UV-Vis adsorption spectra (UV-Vis). The results imply that NPs consist of a crystalline magnetite core and an amorphous silica shell. The silica shell thickness can be controlled from 12.5 nm to 45 nm by varying the experimental parameters. The reaction time, the ratio of TEOS/Fe3O4, and the concentration of hydrophilic Fe3O4 seeds were found to be very influential in the control of silica shell thickness. These well-dispersed core-shell Fe3O4@SiO2 NPs show superparamagnetic properties at room temperature.
采用改进的Stöber 法，以 20nm 亲水性 Fe3O4 NPs 为种子，制备了具有可控二氧化硅壳层厚度的磁铁矿（Fe3O4@SiO2）核壳纳米粒子（NPs）。采用 X 射线衍射（XRD）、透射电子显微镜（TEM）、高分辨率 TEM（HRTEM）、选区电子衍射（SAED）和紫外-可见吸收光谱（UV-Vis）对核壳 NPs 进行了表征。结果表明，NPs 由结晶磁铁矿核和非晶态二氧化硅壳组成。通过改变实验参数，可将二氧化硅壳层厚度从 12.5nm 控制到 45nm。反应时间、TEOS/Fe3O4 比以及亲水性 Fe3O4 种子的浓度被发现对控制二氧化硅壳层厚度有很大的影响。这些分散良好的核壳 Fe3O4@SiO2 NPs 在室温下表现出超顺磁性。
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