Magnetite (Fe3O4) tetrakaidecahedral microcrystals: Synthesis, characterization, and micro-Raman study

A novel and simple method to prepare Fe3O4 tetrakaidecahedral microcrystals has been demonstrated using a two-step refluxing and calcination process. Firstly, Fe(NO3)3∙ 9H2O was dissolved in diethylene glycol by refluxing at 190 °C for 3 h. Secondly, the above solutions were injected into covered quartz crucibles and placed in a tube furnace, and the as-prepared Fe3O4 tetrakaidecahedra were obtained after calcination at 800 °C in an N2 atmosphere for 3 h. Fe3O4 tetrakaidecahedra were studied with Raman scattering spectroscopy, and a clear direct phase transition from magnetite to hematite (α-Fe2O3) due to laser irradiation was observed in the Raman scattering measurements. This oxidation route is specific to magnetite of larger crystalline size, which is coincident with the microcrystalline feature revealed by scanning electron microscopy measurements.