Preparation and microwave absorbing properties of graphene oxides/ferrite composites

摘要

The graphene oxides (GO) and the graphene-based composites have been synthesized successfully by Hummer method and Hydrothermal-calcination process, respectively. The effects of solvent (water, ethylene glycol, glycerol and glycol-glycerol), the consumption of graphite oxides (GO = 0.1, 0.5, 1.0, 2.0 wt%) on the crystallization, morphology and performance of the target samples have been investigated. The obtained samples have been characterized by FTIR, XRD, SEM and HRTEM. The precursors obtained through hydrothermal process are composed of 80 nm ferromagnetic polyhedral particles and the uniformly distributed covering GO layers. After calcination, the 200 nm ferromagnetic nanoparticles can be achieved on the surface of graphene films. The results indicate that the optimized samples can be obtained at GO = 0.1 wt% under water system. Also, the electromagnetic properties and microwave absorbing performance have been measured by VNA. The addition of GO is conducive to improve the absorbing property of ferrites by shifting the reflectivity peak into lower frequency range and sharping the maximum value. At GO = 0.1%, the maximum RL peaks can reach —17.15 dB at 3.3 GHz, with the bandwidth below -10 dB ranging from 2.8 to 3.8 GHz under 3 mm thickness. For GO = 1.0 wt%, twin peaks appear at 4.3 and 15.6 GHz of 3.5 mm thickness, and the bandwidth below -10 dB reaches 2.6 GHz (10.3-12.9 GHz) at 1.5 mm thickness.