Preparation and characterization of MnFe2O4 by a microwave-assisted oxidative roasting process

Abstract

An innovative and effective technological process is proposed to synthetize spinel manganese ferrite (MnFe2O4) by a microwave-assisted oxidization roasting process. In the current paper, the effect of operating variables on the formation mechanism of Fe-MnO systems for synthesizing spinel MnFe2O4 is initially investigated to reveal the oxidation mechanism and phase transformation during the microwave–assisted oxidative roasting process. The synthetic MnFe2O4 microparticles with a saturation magnetization (Ms) of 70.5 emu/g, a coercivity (Hc) of 4.65 Oe and a ratio of the saturation magnetization to remanent magnetization (Ms/Mr) of 0.055 were successfully prepared by heating for 30 min at 1000 °C in an air atmosphere. The MnFe2O4 samples exhibited normal and inverse spinel crystal structures, inevitably coexisting and co-transforming simultaneously at high temperature (≥950 °C). Furthermore, this innovative and effective technological process can be extended to fabricate other spinel ferrite particles of interest.