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

•Manganese ferrites MnFe2O4 was synthesized by microwave-assisted roasting process.•Oxidation behavior of synthetic MnFe2O4 was studied in air atmosphere.•Morphologies and magnetism property of the synthetic MnFe2O4 was clarified.•The formation mechanism and interfacial reaction of MnFe2O4 were clarified.•Manganese ferrites with a saturation magnetization of 70.5 emu/g was prepared.