Preparation of graphene-carbonyl iron powder@tri-iron tetroxide composite and its better microwave absorption properties

Abstract

Carbonyl iron powder (CIP) is a magnetic material with high saturation magnetization and good thermal stability. However, CIP itself has high conductivity, which makes it difficult to match the impedance of free space when designing the microwave absorbing materials, coupled with a single loss mechanism, which inevitably limits its performance. In this paper, through the scheme of complementary properties of CIP and tri-iron tetroxide, the conductivity of CIP is reduced, the saturation magnetization of the composite material is ensured, and the impedance matching of microwave absorption is improved. Moreover, when graphene is introduced into the material system, the absorbing properties of the composite are greatly improved. A method of combining wet chemical oxidation with a bridging method to prepare reduced graphene oxide-carbonyl iron powder @ tri-iron tetroxide (RGO-CIP@Fe3O4) absorbent, which has better microwave absorption performance regarding reflectance loss and absorption bandwidth, is reported. The minimum reflection loss is − 53.3 dB at 10.9 GHz, and the maximum effective microwave absorption bandwidth (RL < − 10 dB) at 2.5 mm thickness is 6.4 GHz (11.6–18 GHz). Due to its thin thickness, light weight, strong absorption, and wide bandwidth, the composite is considered to have great potential as a new type of high-efficiency microwave absorbent.