Fe₃O₄-Ag heterostructure nanocrystals with tunable Ag domains and magnetic properties

Fe₃O₄-Ag dimers and multimers with tunable Ag domains and magnetic properties were prepared by a seeding growth method. The reaction mechanism based on the attraction between Ag precursor and Fe₃O ₄ particles as well as the migration of adsorbed Ag species towards the initially deposited Ag domain was proposed to explain the heterogeneous nucleation of Ag on Fe₃O₄ and the tuning of Ag crystal numbers. Ligand oleic acid, low reaction temperature, large seeding particle and nonpolar solvent are found to be favourable to the growth of Fe ₃O₄-Ag HNCs with more discrete Ag domains. The Fe ₃O₄-Ag HNCs show composition and structure related magnetization behaviour and MR contrast effect, which can be developed into a dual function material for bio-therapy when utilizing the plasmonic, fluorescent or antibacterial properties of Ag at the same time.