IR STUDIES OF THE PHASE-TRANSFORMATION OF FE2O3-DOUBLE-RIGHT-ARROW-FE3O4 BY MAGNETOMECHANICAL ACTIVATION

The phase transformation of hematite alpha-Fe2O3 into magnetite Fe3O4 during wet milling in vacuum as a result of mechanochemical process ha s been investigated by infrared spectroscopy. The FTIR spectra were re corded in the wavenumber range from 400 to 4000 cm(-1). Two very stron g bands were generally observed: one in the range 557-577 cm(-1) with shoulders in 632-693 cm(-1), the other at about 475 cm(-1). The most i mportant feature is a very strong dependence of the intensities of the main absorption bands on the milling time of the sample. In addition, there was a broad band in the 3000-3700 cm(-1) region related to the appearance of a certain number of OH groups in the spinel lattice. The results are discussed assuming the theoretically indicated active IR modes for ferrites. A little disorded was interpreted as generated by ball milling and no traces of amorphization were observed.