Novel peanut-like α-Fe2O3 superstructures: Oriented aggregation and Ostwald ripening in a one-pot solvothermal process

In this work, novel peanut-like alpha-Fe2O3 superstructures were prepared successfully by a simple one-pot solvothermal method independent of surfactants or templates. The as-obtained products were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The SEM and TEM results revealed that the peanut-like superstructures had thin waists and hemispherical ends, and were composed of hematite nanoplatelets (end sections) and irregular blocks (center sections). By properly monitoring the reaction condition and component of the reaction system, the morphology of the alpha-Fe2O3 superstructures can be tuned to be elliptic, rhombic and olive-like. Based on a series of contrast experiments, the probable growth mechanism and fabrication process involving oriented aggregation and Ostwald ripening of the peanut-like structures were proposed. The magnetic hysteresis measurement indicated that the as-obtained alpha-Fe2O3 superstructures exhibited ferromagnetic behaviors with wide open M-H loop (the coercivity of the sample was 3836.9 Oe). (C) 2011 Elsevier B.V. All rights reserved.