Study on the formation and phase transformation of 1D nanostructured Fe3O4 particles under an external magnetic field

This paper described the preparation of one-dimensional (1D) chains of Fe3O4 particles via oxidation–coprecipitation phase transformation under an external magnetic field (EMF). The phase transformation of magnetite (Fe3O4) under an EMF was investigated using the as-obtained Fe3O4 as the control. Fe3O4 nanoparticles formed a 1D chain structure under a low EMF during preparation. Higher EMF values accelerated the phase transformation of Fe3O4. Analysis of the mechanism of this phenomenon showed that the EMF accelerated the dissolution of the 1D Fe3O4 nanocrystals, resulting in a sufficient Fe(III) concentration for alpha-lepidocrocite (α-FeOOH) nucleation. α-FeOOH was further transformed into an alpha-hematite (α-Fe2O3) under the EMF via the catalytic effect of Fe(II) ions.