Mössbauer spectroscopic investigations of nanophase iron oxides synthesized by thermal plasma route

Magnetic nanoparticles of iron oxide were synthesized by transferred arc plasma induced gas phase condensation method. Structural, morphological and magnetic studies of the as synthesized powder were carried out using X-ray diffraction, transmission electron microscopy and Mössbauer spectroscopy. These studies have revealed the simultaneous nucleation and condensation of different magnetic phases with a broad size distribution of the nanoparticles which is peaked at 30-50 nm and ranges from 10 nm to 80 nm. ⁵⁷Fe Mössbauer spectra recorded at various temperatures (5 K-300 K) in presence of external magnetic field (at 5 K) have suggested the presence of different phases of iron oxide with sizable amounts of γ-Fe₂O₃ and α-Fe₂O₃ in addition to Fe₃O₄. The relative concentrations of these phases have been obtained by a self consistent spectral area analysis and were found to be 44:22:34 (%).