Hierarchical porous Fe3O4/RGO nanocomposite powders as high performance microwave absorbers

Abstract

Fe3O4/reduced graphene oxide (RGO) composite powders were prepared by solution combustion synthesis method. The effects of fuel type; glycine and urea; on the structure, microstructure, magnetic, and microwave absorption properties were characterized by modern methods. A mixture of α-Fe2O3 and Fe3O4 phases was obtained by the urea fuel, while the glycine fuel led to the pure Fe3O4 phase. The scanning and transmission electron microscopy showed the Fe3O4 nanoparticles were distributed on the ultrathin RGO sheets. With the addition of RGO, the saturation magnetization increased up to 84 emu/g due to the higher amounts of the magnetite phase. The Fe3O4/RGO composite powders synthesized by the urea fuel showed a reflection loss (RL) of −28 dB with effective bandwidth of 1.4 GHz in the C1 band at the matching thickness of 3.7 mm. However, the pristine Fe3O4 powders prepared by the glycine fuel had higher absorption properties, including higher RL of −33 dB and broader bandwidth of 3 GHz in the Ku band at the matching thickness of 1.2 mm. In addition to the higher magnetic and dielectric losses, the higher microwave absorption performance was attributed to the better impedance matching property caused by the porous microstructure.