Electric field induced structural color changes of highly monodisperse hollow Fe3O4@C colloidal suspensions

Abstract Highly dispersed hollow Fe 3 O 4 @C nanoparticles with controllable particle sizes were prepared. Hollow Fe 3 O 4 @C nanoparticles were chosen not only because of their low density and high optical contrast, but also because of high refractive index, better optical properties. Corresponding colloidal suspension of hollow Fe 3 O 4 @C photonic crystals in propylene carbonate showed a highly adjustable structure color change upon applying of electric fields. After being stored for 28 days in propylene carbonate solution, these colloidal suspensions can still diffract visible lights when an electric field was applied, which is attributed to low density. Based on the dielectric spectroscopy analysis of hollow Fe 3 O 4 @C and SiO 2 @Fe 3 O 4 @C colloidal suspensions,a dielectric loss model has been proposed to explain the effect of surface properties on the assembly.