Fabrication of octahedral magnetite microcrystals

Octahedral magnetite microcrystals were synthesized by a simple hydrothermal route. The morphology and structure of magnetite microoctahedrons were characterized by XRD, IR, SEM, EDS, TEM and ED. The results showed that the as-synthesized sample exhibits octahedral structures and the size ranges from 4 to 10 μm. It is suggested that the driving force for the anisotropic growth of magnetite octahedrons derives from the surface tension, the inherent crystal structure of magnetite and its chemical potential in concentrated NaOH solution. It is also found that the surfactant, NaOH concentration and reaction temperatures have great influence on the morphology and structure of the final sample. Magnetic measurements at room temperature indicate that the saturation magnetization and the coercive field of octahedral Fe3O4 are about 93.3 emu/g and 86 Oe, respectively.