Hierarchical brain-coral-like structure (3D) vs rod-like structure (1D): Effect on electromagnetic wave loss features of SrFe12O19 and CoFe2O4

Morphological configuration plays a vital role in regulating the absorption performance of magnetic materials. Herein, a novel challenge is discussed on electromagnetic loss features of two hard and soft magnetic materials with hierarchical brain-coral like structure and rod-like structure. In this study, pure SrFe12O19 (Sr) as hard magnetic component and CoFe2O4 (Co) as soft magnetic component with two distinct morphologies were successfully synthesized by facile hydrothermal and solvothermal methods. In the first approach, electromagnetic loss features of rod and brain-coral-like particles were investigated, and in second approach-according to the obtained results-microwave absorption performance of a mixture of hard/soft magnetic components with hierarchical structure were evaluated. The minimal reflection loss (RL) for brain-coral-like particles of individual Sr and Co samples were -17.6 dB (at 18.8 GHz with 9 mm thickness) and -31.2 dB (at 8.1 GHz with 10 mm thickness), respectively, which show far better performance than rod-like structure. Remarkably, the composite of Sr and Co micro-particles with hierarchical structure exhibited strong RL value of-38 dB with 2.6 GHz effective absorption bandwidth at the thickness of 2.5 mm, with a filling ratio of 40 wt%. According to the results, it is founded that the electromagnetic loss features are crucially boosted via hierarchical configuration of magnetic materials. Increment in complex permittivity and permeability, accounting for the formation of cross linked networks in the hierarchical structure, promoted the interfacial polarization phenomena with different relaxation times and appearance of multi resonance peaks.