7th INTERNATIONAL CONFERENCE ON FERRITES

J. Phys. IV France 07 (1997) C1-615-C1-616
DOI: 10.1051/jp4:19971255

IR Studies of the Phase Transformation of Fe₂O₃ → Fe₃O₄by Magnetomechanical Activation

I. Jacyna-Onyszkiewicz¹, M. Grunwald-Wyspianska² and W.A. Kaczmarek<sup>3

1</sup>  Institute of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznan, Poland
²  Department of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland
³  Institute of Advanced Studies, Research School of Physical Sciences and Engineering, Australian National University, Canberra, A.C.T. 0200, Australia

Abstract
The phase transformation of hematite αFe₂O₃ into magnetite Fe₃O₄ during wet milling in vacuum as a result of mechanochemical process has been investigated by infrared spectroscopy. The FTIR spectra were recorded in the wavenumber range kom 400 to 4000 cm^-1. Two very strong bands were generally observed : one in the range 557-577cm^-1 with shoulders in 632-693 cm^-1, the other at about 475 cm^-1. The most important 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 ferites. A little disorded was interpreted as generated by ball milling and no traces of amorphization were observed.

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