Controllable synthesis, formation mechanism and magnetic properties of hierarchical α-Fe2O3 with various morphologies

In this paper, a simple and efficient route had been developed for morphology-controlled synthesis of hierarchical alpha-Fe2O3 superstructures assembled by nanocrystallites. All chemicals used were low-cost compounds and environmentally benign. The morphologies and structures of the alpha-Fe2O3 crystals were characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and Fourier-transform IR spectroscopy (FTIR). The results showed that different shapes of hierarchical alpha-Fe2O3 nanostructures such as peanuts-like, capsule-like, cantaloupe-like and almond-shaped could be prepared by simply varying the concentration of silicate anions and other inorganic reagents. The as-prepared alpha-Fe2O3 architectures were composed of nanorods or nanosheets at different synthesis temperature. The possible formation mechanism was described based on the experimental results. Magnetic hysteresis measurements revealed the as-prepared superstructures displayed ferromagnetic behavior with higher remanence and coercivity at room temperature, which was attributed to the superstructure or the shape anisotropy of the samples. (C) 2012 Elsevier B. V. All rights reserved.