A study of nanosized magnesium ferrite particles with high magnetic moment

• Highest magnetisation (M) among nano sized magnesium ferrite particles was obtained.
• The obtained magnetisation was nearly double of furnace cooled bulk sample.
• Coercivity (Hc) is anti correlated to M for samples with different heat treatment.
• Coefficient of non saturation of magnetisation in M–H loop (a), is correlated with Hc.
• Hc, M and a are explained in terms of cation distribution obtained using NNéel model.

Nano-sized magnesium ferrite particles were prepared by sol gel combustion synthesis and were either furnace cooled or quenched after calcining at various temperatures ranging from 300 to 800 °C. A magnetisation value of 61 emu/g was obtained at 5 K for sample calcined at 800 °C and quenched in liquid nitrogen temperature. This is one of the highest reported values of magnetisation obtained from quenching at such a lower temperature. An estimate of the number of Fe3+ ions on A and B sites was made after applying Néel Model on the magnetisation values measured at 5 K. It was estimated that Fe3+ ions segregates out from both sites disproportionately so as to cause a net decrease in the overall moment. The resultant cation distribution is found to be consistent with the coercivity data.