Synthesis of Controllable Superparamagnetic Nano Fe₃O₄ Based on Reduction Method for Colloidal Clusters of...

In this paper, we designed and investigated a reduction-based method to synthesize controllably monodisperse superparamagnetic nano Fe₃O₄ colloidal clusters for magnetically responsive photonic crystals. It was shown that the addition of ascorbic acid (VC) to the system could synthesize monodisperse superparamagnetic nano Fe₃O₄ and avoided the generation of γ-Fe₂O₃ impurities, while the particle size and saturation magnetization intensity of nano Fe₃O₄ gradually decreased with the increase of VC dosage. Nano Fe₃O₄ could be rapidly assembled into photonic crystal dot matrix structures under a magnetic field, demonstrating tunability to various diffraction wavelengths. The nano Fe₃O₄ modified 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.