Synthesis of strawberry-like Fe3O4@SiO2@Ag composite colloidal particles for constructing responsive photonic crystals

Well-defined Fe 3 O 4 @SiO 2 composite colloidal particles decorated with Ag nanoparticles were successfully synthesized through a simple chemical approach. These particles self-assembled into 1D chain-like photonic structures under the induction of magnetic field and diffract tunable structural colors. The hue and brightness of the structural colors are related to Ag nanoparticles deposited on the particles surface and its brightness increases with the increase of Ag concentration. This phenomenon could be the result of the superposition of photonic bandgap formed by photonic crystals and possible plasmonic property, as well as capability in absorbing stray light of Ag nanoparticles. As-prepared Fe 3 O 4 @SiO 2 @Ag colloidal particles have great potential to be applied in many crucial areas such as color displaying, biological detection and anti-counterfeiting technology.