α-Fe2O3 Nanocrystals: Controllable SSA-Assisted Hydrothermal Synthesis, Growth Mechanism, and Magnetic Properties

alpha-Fe2O3 nanocrystals with different morphologies were successfully synthesized by a facile 5-sulfosalicylic acid dihydrate (SSA)-assisted hydrothermal process, in the absence of any template or surfactant in the system. The chelating ligand SSA, pH values of Fe-SSA complex solution, and alkaline reagents play important roles in the morphological control of the alpha-Fe2O3 nanostructures. Magnetic hysteresis measurements reveal that the size of the nanostructures has a remarkable effect on the magnetic properties at room temperature. A possible formation mechanism for controllable synthesis of these alpha-Fe2O3 nanocrystals was proposed. In addition, the successful synthesis of honeycomb-like hierarchical Ni(OH)(2) structures and Co3O4 microspheres in our experiments gave further evidence for the wide applicability of the SSA-assisted hydrothermal synthesis process. The results suggest that this process may be a convenient and effective approach to controllable synthesis of a variety metal oxides and hydrates nanostructures.