Synthesis, structure and electromagnetic properties of Mn–Zn ferrite by sol–gel combustion technique

The electromagnetic absorbing behaviors of a thin coating fabricated by mixing Mn–Zn ferrite with epoxy resin (EP) were studied. The spinel ferrites Mn1−xZnxFe2O4 (x=0.2, 0.5 and 0.8) were synthesized with citrate acid as complex agent by sol–gel combustion method. The microstructure and surface morphology of Mn–Zn ferrite powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The complex permittivity and complex permeability of the fabricated ferrite/EP composites were investigated in terms of their contributions to the absorbing properties in the low frequency (10 MHz to 1 GHz). The microwave absorption of the prepared ferrite/EP composites could be tailored by matching the dielectric loss and magnetic loss and by controlling the doped metal ratio. The composites with the ferrite composition x=0.2 are found to show higher reflection loss compared with the composites with other compositions. It is proposed that the prepared composites can potentially be applied in electromagnetic microwave absorbing field. - Highlights: • We designed and synthesized Mn1−xZnxFe2O4 (x=0.2, 0.5 and 0.8), with citrate acid as complex agent by the sol–gel combustion method. • Citrate acid as the complex agent overcomes the aggregation of ferrite resulting in high purity and homogeneous particles. • We investigated the electromagnetic absorbing performance of a fabricated thin coating by introducing Mn–Zn ferrite into epoxy resin (EP). • The Mn0.8Zn0.2Fe2O4 composite coatings could achieve the satisfactory absorbing value of −17 dB at 800 MHz. • The prepared composites can potentially be used for the application in electromagnetic microwave absorbing field