Enhanced microwave absorption properties of carbonyl iron/Fe3O4 composites synthesized by a simple hydrothermal method

Carbonyls iron powders (CIPs)/Fe3O4 composites have been prepared by a simple hydrothermal method through controlling the pH value of the reaction system. The obtained products were characterized by X-ray diffraction (XRD), Raman spectrum, scanning electron microscopy (SEM), superconducting quantum interference device magnetometer (SQUID), thermogravimetry–differential thermal analysis (TG–DTA), etc. The microwave absorption properties of the CIP/Fe3O4 composites were measured by vector network analysis (VNA). A wide region of microwave absorption was achieved due to the high permeability of CIP/Fe3O4 composites (pH = 13). When the matching thickness is 2 mm, the reflection loss of the sample exceeding −10 dB was obtained at the frequency range of 8.7–15.0 GHz, with an optimal reflection loss of about −38.1 dB at 11.5 GHz. A possible mechanism of the improved microwave absorption properties of the composites was discussed.

► Higher imaginary part of the complex permeability and higher electric resistivity achieved because of the ferromagnetic property of Fe3O4. ► The reflection loss of the sample exceeding −10 dB was obtained at the frequency range of 8.7–15.0 GHz. ► The optimal reflection loss of −38.1 dB was achieved at 11.5 GHz for the thickness of 2.0 mm.