Construction biomass carbon@BaFe12O19 composites for excellent microwave absorption performance in mid-to-low frequency

In order to cope with the era of artificial intelligence, the centralized use of massive high-power computing equipment will release excessive electromagnetic waves, which leads to serious electromagnetic pollution problems. Therefore, microwave absorbing materials have been proposed to solve this problem, especially microwave absorption (MA) in the low-frequency region is a major challenge in the development of carbon-based absorbers. In this work, BaFe₁₂O₁₉ was deposited on the surface of biomass carbon by hydrothermal method and calcination method. Sheep bone carbon (C) treated with hydrochloric acid functioned as the matrix, and the C@BaFe₁₂O₁₉ core-shell composites with high MA properties were prepared. The lowest reflection loss (RL_min) in the C-band (4–8 GHz) is −67.6 dB (3.52 mm), and the effective absorption bandwidth (EAB) achieves 4.27 GHz (4–6.7 GHz and 16–18 GHz). It effectively encompasses 67.5 % of the frequency range within the C-band. The porous structure of C@BaFe₁₂O₁₉ helps to facilitate enhanced multiwall reflection and scattering of electromagnetic waves. Concurrently, this facilitates enhanced interfacial polarization. The introduction of BaFe₁₂O₁₉ can effectively enrich the loss mechanism while optimizing the impedance matching of C and improving the attenuation capabilities. Therefore, the C@BaFe₁₂O₁₉ composite has special significance for the radiation interference of the fifth generation (5G) technology and the shielding absorption of C-band radar waves.