Designed synthesis of wide range microwave absorption Fe3O4–carbon sphere composite

Fe3O4–carbon sphere composite was synthesized by a simple hydrothermal method. The as-synthesized products were characterized by field-emission scanning electron microscopy (FE-SEM), energy dispersive spectrum (EDS), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and Raman spectrum. The complex permittivity and permeability of paraffin wax and Fe3O4–carbon sphere composite with different volume fraction of the composite were measured by vector network analysis. A wide region of microwave absorption was achieved due to dual dielectric and magnetic losses. When the matching thickness is 4 mm, the calculated reflection loss of the sample with 70% volume fraction of Fe3O4–carbon sphere composite exhibits a broad microwave absorption ranging from 2.5 to 18 GHz.