Hydrothermal Synthesis of Ultrafine α-Fe2O3 and Fe3O4 Powders

Ultrafine α-Fe2O3 and Fe3O4 particles were prepared through a hydrothermal process at 150°C from a (NH4)2SO4·FeSO4·6H2O solution in the presence of hydrazine. These products were characterized by X-ray diffraction and transmission electron microscopy. The formation of pure α-Fe2O3 and Fe3O4 powders was strongly influenced by the pH values of the aqueous solution.