Preparation and formation mechanism of different α-Fe2O3 morphologies from snowflake to paired microplates, dumbbell, and spindle microstructures

Different morphologies of alpha-Fe2O3 crystals including snowflake-like, paired microplates, dumbbell, column, and spindle microstructures have been prepared though a hydrothermal reaction in K-3[Fe(CN)(6)] solution with different pH values at 140 degrees C. The influences of the experimental conditions, such as pH value and reaction time on the morphologies of the as-prepared alpha-Fe2O3 crystals, have been studied. The morphologies and structures of the alpha-Fe2O3 crystals have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Selected-area electron diffraction confirms that the snowflake-like microstructure and paired microplates grow along the [001] direction, respectively. A possible growth process of alpha-Fe2O3 crystals with varied morphologies from sixfold snowflake-like to the column-like microstructure has been proposed. Additionally, magnetic investigations show that the alpha-Fe2O3 crystals with column-like microstructures exhibit a weakly ferromagnetic property at room temperature.