Preparation of Fe3O4 and γ-Fe2 O3 powders by magnetomechanical activation of hematite

Total phase transformation of hematite to magnetite was accomplished at room temperature by wet magnetomechanical activation of hematite. Low energy mechanical activation of the oxide surface is sufficient to effect the transformation. Oxygen bonds on α-Fe₂O₃ oxide surface are apparently broken during the mechanical activation process and oxygen is released (removed) to the dispersing polar liquid. The oxygen pressure during the process as well the nature of the dispersing liquid have a critical influence on successful and fast phase transformation. Thus, all preparations performed in air, dry conditions or with nonpolar hydrocarbons (benzene, anthracene) show that the process of hematite reduction is non existent or very slow. Normal air pressure and/or application of hydrocarbons suppress the transformation