Mossbauer spectroscopy study of aluminium substituted nickel-ferrites

Powders of Al substituted Ni-ferrites (NiAlxFe2-xO4 x = 0, 0.5, 1.0 and 1.5) were prepared using the calcination method. Mossbauer spectroscopy results of all samples show two well defined magnetic sextets corresponding to Fe3+ ions in the A (tetrahedral) and B (octahedral) sites of the spinel structure. In addition, a quadrupole doublet with quadrupole splitting of (similar to 0.53 mm/s) starts evolving upon Al substitution. This doublet is associated with a new Fe-Al-oxide phase. The X-ray diffraction patterns show, in addition to the original peaks, new peaks evolve and increase in intensity as the Al concentration increases, confirming the evolution of this new phase.