Structural and magnetic characterization of the ball-milled α-Fe2O3-Mn2O3 and α-Fe-Mn2O3 systems

In this work, the (Fe2O3)(x)(Mn2O3)(1-x) and Fe-y(Mn2O3)(1-y) systems were mechanically processed in a high-energy ball-mill. The as-milled powders were structurally and magnetically characterized by X-ray diffraction, Mossbauer spectroscopy and magnetic measurements. Under similar milling settings and conditions, dissimilar behaviors were observed in the studied systems. In the oxide-oxide system, only the bixbyite (Mn,Fe)(2)O-3 phase was obtained in all the analysed samples, whereas in the metal-oxide system, a sharp compositional dependence for the final milling products was observed. For yless than or equal to0.40, the FeMn2O4 spinel phase was detected and, for y>0.40, a wustite-like phase of the (Fe, Mn)(1-y)O type was formed. It was observed that magnetization in both systems increased with the nominal concentration, x or y, of the magnetic precursors, up to half of the concentration maximum and then it decreased as a result of structural phase transformations. (C) 2004 Elsevier B.V. All rights reserved.