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

Strontium ferrites/graphene (SrFe12O19/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 SrFe12O19 nanoparticles with a diameter of 60–70 nm were well distributed on the graphene. The formation of SrFe12O19 nanoparticles and the reduction of graphene oxide were accomplished simultaneously. The re-stacking of graphene sheets and the aggregation of SrFe12O19 nanoparticles were inhibited. The as-obtained composites exhibited better absorbing properties than the pristine SrFe12O19 particles due to the synergistic effect of SrFe12O19 and graphene. The minimum reflection loss (RL) of SrFe12O19/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 SrFe12O19 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.