Synthesis of pure amorphous Fe2O3

Abstract

A method for the preparation of pure amorphous Fe2O3 powder with particle size of 25 nm is reported in this article. Pure amorphous Fe2O3 can be simply synthesized by the sonication of neat Fe(CO)5 or its solution in decalin under an air atmosphere. The Fe2O3 nanoparticles are converted to crystalline Fe3O4 nanoparticles when heated to 420 °C under vacuum or when heated to the same temperature under a nitrogen atmosphere. The crystalline Fe3O4 nanoparticles were characterized by x-ray diffraction and M¨ossbauer spectroscopy. The Fe2O3 amorphous nanoparticles were examined by Transmission Electron Micrography (TEM), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and Quantum Design SQUID magnetization measurements. The magnetization of pure amorphous Fe2O3 at room temperature is very low (<1.5 emu/g) and it crystallizes at 268 °C.