Mössbauer spectroscopy study of mechanically alloyed Fe₂O₃–(Al, Co and WC) systems

Abstract

Mössbauer spectroscopy revealed that a central hyperfine interaction doublet and an additional sextet characterized the appearance of new phases in the mechanically alloyed Fe₂O₃–Al and Fe₂O₃–Co systems. In the Fe₂O₃–Al system, the intensity of the central super paramagnetic doublet which represents small particles of iron, increased with increasing milling time from 5 to 30 h of mechanical alloying. The magnetic sextet characterizing hematite vanished in the room temperature Mössbauer spectra of samples produced after 25 h of mechanically alloying the 50% Fe₂O₃ and 50% Al system. In general XRD peak broadening was observed as a result of extensive material structural distortion and formation of small particles. Fe, Al₂O₃ and mixed iron–aluminium oxide phases were identified in the XRD patterns with a small persistence of the iron oxide up to 20 h of mechanically alloying the 1:1 system Al–Fe₂O₃. In the 50% Co–50% Fe₂O₃ system, a 55% abundant new phase CoFe₂O₄ was observed, from the Mössbauer spectra of the system. The presence of this new phase was confirmed by the XRD analysis. The high energy ball milling of WC–Fe₂O₃ revealed a more effective grinding compared to hematite alone. The hematite particles were reduced to nanosized particles.