Fabrication, magnetic properties and self-assembly of hierarchical crystalline hexapod magnetites

Abstract

We report a facile and surfactant-free solvothermal approach for the shape controlled synthesis of magnetite (Fe₃O₄). Hierarchical branched hexapod magnetites with various secondary structures can be prepared from ferrocene by using different solvents and tailoring experimental parameters. The as-prepared hexapods were characterized by X-ray diffraction, room temperature ⁵⁷Fe Mössbauer spectroscopy, and scanning and transmission electron microscopy. Compared with bulk magnetite, the obtained Fe₃O₄ hexapods are single crystals and exhibit different ferrimagnetic behavior with relatively high specific saturation magnetization (90–128 emu g⁻¹) and large coercivity (223–238 Oe) values depending on their size and morphology. Self-organization of the shape-anisotropic hexapod crystals has been achieved for the first time by evaporation-mediated assembly. The well-defined hexapod Fe₃O₄ crystals will be attractive as promising building blocks for the bottom-up design of advanced materials and devices which may have applications in many fields.