One-step in situ synthesis of strontium ferrites and strontium ferrites/graphene composites as microwave absorbing materials

Strontium ferrites/graphene (SrFeO/G) composites were synthesized by a facile one-step surfactant assisted hydrothermal method. The structure, magnetic properties and electromagnetic parameters of the as-prepared composites were evaluated. Uniform SrFeO nanoparticles with a diameter of 60-70 nm were well distributed on the graphene. The formation of SrFeO nanoparticles and the reduction of graphene oxide were accomplished simultaneously. The re-stacking of graphene sheets and the aggregation of SrFeO nanoparticles were inhibited. The as-obtained composites exhibited better absorbing properties than the pristine SrFeO particles due to the synergistic effect of SrFeO and graphene. The minimum reflection loss (RL) of SrFeO/G composites with the thickness of 3 mm reached -34.8 dB at 13.6 GHz, and the effective absorption bandwidth (RL < -10 dB) was 5.7 GHz. However, the minimum RL of the SrFeO particles only reached -13.5 dB, and the effective absorption bandwidth was 4.6 GHz. A possible mechanism for the enhanced absorbing performance was proposed.