Synthesis, permeability resonance and microwave absorption of flake-assembled cobalt superstructure

To meet the demands of high-efficient microwave absorption materials, cobalt superstructure was synthesized and characterized. As SEM confirmed, the cobalt superstructure was assembled by flakes. The size of cobalt superstructure was about 10μm, and the thickness of the flake was about 500nm. The permittivity and permeability were investigated as a function of frequency in the microwave range of 1–18GHz. Based on the LLG equation and exchange resonance mode, three magnetic resonances, including one natural resonance and two exchange resonances were discussed. The calculated reflection loss (RL) indicated the cobalt superstructure indicated the cobalt superstructure has potential application as a promising candidate for microwave absorption. The maximum RL reached as high as −77.29dB with a matching thickness of 1.5mm, and the effective bandwidth with a reflection loss less than −10dB was 3.6GHz from 9.85 to 13.45GHz. For cobalt superstructure, magnetic loss mainly contributed even more than dielectric loss to the microwave absorption. •The cobalt superstructure were synthesized and characterized.•The multiple magnetic resonances were studied for cobalt superstructure based on the LLG equation and exchange resonance mode.•The maximum reflection loss of cobalt superstructure reaches to −77.29dB.