Reduction recalcination behaviour and magnetic properties of nanocrystalline Mn 0˙2 Zn 0˙8 Fe 2 O 4

Abstract

Manganese zinc ferrite (Mn_0˙2Zn_0˙8Fe₂O₄) was synthesised in nanocrystalline (25 nm) powder through a hydrothermal precipitation route. The produced powder of Mn_0˙2Zn_0˙8Fe₂O₄ was isothermally reduced with pure hydrogen at 600–800°C. Based on thermogravimetric analysis, the reduction behaviour and kinetics of manganese zinc ferrite were studied. The initial ferrite powder and the various reduction products were characterised by X-ray diffraction analysis, scanning electron microscope and vibrating sample magnetometer to reveal the effect of hydrogen reduction on composition, microstructure and magnetic properties of produced samples. Also the reduced products were recalcinied at 1200°C for 3 and 6 h. Homogenous Fe/MnO/Zn nanocrystalline (70˙6 nm) composite was obtained by reduction of Mn_0˙2Zn_0˙8Fe₂O₄ powder. By recalcination of the reduced products, incomplete resynthesis of Mn_0˙2Zn_0˙8Fe₂O₄ powder was observed. The magnetic characterisation of the formed Fe/MnO/Zn composite was enhanced under the effect of reduction temperature whereas the coercivity values decreased from 120˙2 to 44˙97 Oe while the saturation magnetisation increased from 156˙2 to 194˙3 emu g^-1.