Silica-coated iron nanocubes: Preparation, characterization and application in microwave absorption

Novel cubic nanocapsules consisting of metallic iron core and amorphous silica shell were fabricated through a simple chemical reduction route followed by a Stöber process. Thus-prepared Fe@SiO2 nanocubes were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectrometer (XPS), Fourier transform infrared spectrometer (FTIR), thermogravimetry-differential thermal analysis (TG-DTA), vibrating sample magnetometer (VSM) and scalar network analysis (SNA). Comparing with that of pure iron counterparts, silica-coated iron nanocubes exhibited improved magnetic properties, oxidation resistance and microwave absorption performance. A reflection loss (RL) exceeding −12 dB was obtained in the frequency range of 8–14 GHz for an absorber thickness of 2 mm, with an optimal RL of −18.2 dB at 9 GHz. Mechanism of the improved microwave absorption properties of the Fe@SiO2 composite was discussed based on their magnetic properties and electromagnetic theory.

Graphical abstractSilica-coated iron nanocubes exhibited improved magnetic properties, oxidation resistance and microwave absorption performance as compared with the iron cubes without silica coating.Figure optionsDownload full-size imageDownload high-quality image (110 K)Download as PowerPoint slide