Synthesis of Controllable Superparamagnetic Nano Fe3O4 Based on Reduction Method for Colloidal Clusters of Magnetically Responsive Photonic Crystals

In this paper, we designed and investigated a reduction-based method to synthesize controllably monodisperse superparamagnetic nano Fe3O4colloidal clusters for magnetically responsive photonic crystals. It was shown that the addition of ascorbic acid (VC) to the system could synthesize monodisperse superparamagnetic nano Fe3O4and avoided the generation of γ-Fe2O3impurities, while the particle size and saturation magnetization intensity of nano Fe3O4gradually decreased with the increase of VC dosage. Nano Fe3O4could be rapidly assembled into photonic crystal dot matrix structures under a magnetic field, demonstrating tunability to various diffraction wavelengths. The nano Fe3O4modified by polyvinylpyrrolidone (PVP) and silicon coated could be stably dispersed in a variety of organic solvents and thus diffracted different wavelengths under a magnetic field. This is expected to be applied in various scenarios in the field of optical color development.