COMPARATIVE-STUDY OF THE MECHANOCHEMICAL ACTIVATION OF MAGNETITE (FE3O4) AND MAGHEMITE (GAMMA-FE2O3)

A comparative study on the kinetics and mechanism of mechanochemical a ctivation (by high energy grinding) of magnetite (Fe3O4) and maghemite (gamma-Fe2O3) has been carried out. It has been established that duri ng the activation the crystal lattice is distorted and phase and struc ture transformations occur. The phase compositions of intermediate and final products are registered by Mossbauer spectroscopy and X-ray ana lysis. It was found that the end product of mechanochemical activation of Fe3O4 and gamma-Fe2O3 is highly dispersed hematite. The kinetics o f phase changes are determined for the two iron oxides which are chara cterized by different valency states and cation distributions in the s pinel lattice. The different rates of phase transformations have been explained by a phonon mechanism of energy dissipation for maghemite an d a mixed phonon-electron mechanism for magnetite.