Synthesis and Electromagnetic and Microwave Absorption Properties of Monodispersive Fe3O4/α-Fe2O3 Composites

Fe3O4/α-Fe2O3 composites were synthesized by a one-step method. The composition and their performances were modified by adjusting the concentration of Fe3+ (FeCl3·6H2O) in the precursor solution, effectively. Compared with single-phase Fe3O4 and Fe2O3, the effective microwave absorbing ability of Fe3O4/α-Fe2O3 composites is much widened in the range 1–18 GHz, which could stem from the enhanced dipolar polarization and interfacial polarization due to lattice dislocations at the interface of Fe3O4/α-Fe2O3. The minimum reflection loss (RL) of Fe3O4/α-Fe2O3 composites reaches about −43.1 dB at a thickness of 2.0 mm, with the effective absorption band reaching 3.4 GHz (9.8–13.2 GHz). In the thickness of 1.5–3.2 mm, the width of the RL reaches 9.9 GHz (3.5–13.4 GHz). The results demonstrate that Fe3O4/α-Fe2O3 composites could be a candidate to be used as absorbers with the microwave absorption band much widened.