Superparamagnetic iron oxide nanoparticles for full-color photonic materials with tunable properties

Abstract

Abstract To obtain full-color tunable photonic materials, superparamagnetic nanoparticles with a tunable particle diameter and highly charged surfaces were synthesized through a modified solvothermal process. Compared with polyelectrolyte-capped nanoparticles, citrate-capped nanoparticles are simple, cost-effective, and suitable as building blocks of tunable photonic materials. The reflection spectra of superparamagnetic colloid under a varing magnetic field covers a broad wavelength range of approximately 420–820 nm due to the assembly of Fe3O4 nanoparticles. The effect of the optical properties of colloids on variables such as the nanoparticle size, nanoparticle concentration, ionic strength, and pH value was studied. After superparamagnetic Fe3O4 nanoparticle was coated with a layer of silicon dioxide, their reflection spectra covered the electromagnetic range from the visible to near-infrared region. Superparamagnetic colloids can produce structural colors with engineered nanostructures, which indicates that citrate-capped Fe3O4 nanoparticles and Fe3O4@SiO2 core-shell nanoparticles as photonic materials are promising candidates for achieving full-color display.