Gram-scale synthesis of superparamagnetic Fe3O4 nanocrystal clusters with long-term charge stability for highly stable magnetically responsive photonic crystals.

We report the gram-scale hydrothermal synthesis of superparamagnetic Fe3O4 CNCs with superior long-term charge stability, which are suitable building blocks for magnetically responsive photonic crystals (MRPCs) with widely, rapidly and reversibly tunable diffractions across the visible and near IR range, as well as long-term stability of photonic performances. The scalable synthesis of Fe3O4 CNCs with excellent long-term colloidal stability will facilitate their wide application in photonics, biomedicine, catalysis and other areas.