On the Question of Thermal Stability and Magnetic Properties of Mn0.6Zn0.4Fe2O4 Nanoparticles Prepared by Sol-Gel Method

Mn-Zn ferrite nanoparticles of Mn_0.6Zn_0.4Fe₂O₄ composition were synthesized through sol-gel auto combustion process. The phase formation, thermal stability, morphology, and magnetic properties of as-prepared and heat treated samples have been investigated. It is observed that as-prepared spherical particles (10–40 nm) transform into single phase spinal structure of \(\sim 500\) nm long cylindrical rods of 60 nm diameter, when annealed at 1200 °C in air. Interestingly, when the samples were annealed at 600 °C in air Fe₂O₃, Mn₂O₃ impurity phases appear along with poor quality ferrite phase. On the other hand, samples annealed at 600 °C, under inert gas conditions showed well-ordered single phase spinal structure with large \(\text{M}_{\mathrm {\mathbf {s}}} =60\) emu/g and \(\text{H}_{\mathrm {\mathbf {c}}} =55\) Oe. Furthermore, it is shown that on rapid cooling, the sample from 1200 °C yields a good quality spinel structure with enhanced soft magnetic properties ( \(\text{M}_{\mathrm {\mathbf {s}}} =62.3\) emu/g; \(\text{H}_{\mathrm {\mathbf {c}}} = 3\) Oe).