Defects in Discrete Nanocrystals of Thin‐Shelled Amorphous Carbon Induced Dipole Polarization for Boosting Broadband Response

Abstract

Discrete nanocrystals, curvature, and core‐shell structures synergistically trigger intense polarization for amorphous carbon to achieve broadband microwave absorption. However, the distinguishable effects of the defects in amorphous carbon on microwave dissipation remain challenging, and the identification of critical factors for enhancing dipole polarization requires further clarification. Herein, collective engineering of defects and concavities in thin‐shelled hollow amorphous carbon with discrete graphite nanocrystals is proposed to identify the effective pathways of dielectric loss for broadband response and strong microwave absorption. The appropriate conductive net and charge imbalance is the primary essential factor to enhance dielectric loss capacity; then defects in thin‐shelled amorphous carbon, induced intense dipole polarization, are more critical to achieve broadband response than concavity and geometry effect. As a result, the thin‐shelled hollow amorphous carbon with more defects demonstrates a more remarkable broadband response capability with an effective absorption bandwidth (reflection loss, RL≤ −10 dB) of 8.08 GHz and efficient dissipation of −80.70 dB. This work not only provides carbon microwave absorbing materials with broadband response, meanwhile strong microwave absorption but also proposes critical insights into the polarization loss mechanisms associated with defects in amorphous carbon.