The effect of urea-to-nitrates ratio on the morphology and magnetic properties of Mn0.8Mg0.2Fe2O4

Mn_0.8Mg_0.2Fe₂O₄ ferrite was synthesized using flash auto-combustion technique using urea as fuel. The effect of the urea-to-nitrates ratio was examined and found to affect the samples characteristics. The as-burnt powder was crystallized in single-phase spinel structure of cubic symmetry. The lattice parameter was decreased with increase in the urea-to-nitrates ratio (n) while the crystal size increased from 21 to 42 nm with n changing from 6.67 to 10. The coercivity increases while the saturation and remanence magnetization decreases with increase in n. This was attributed to the disturbance of the spin order as a result of the surface effects.