Boosting microwave absorption performance of bio-carbon flakes via magneto-alignment

Abstract

Besides composition, macrostructure of a material is also crucial to its microwave absorption performance. In this work, we demonstrate a magneto-alignment effect on the microwave absorption property of the bio-carbon flakes synthesized from phoenix tree leaves. When a magnetic field is applied, the prepared bio-carbon flakes tended to be aligned into a desired direction due to their diamagnetic feature. Moreover, a rotating magnetic field has a better magneto-alignment effect than a static one, which significantly boosts microwave absorption efficiency. By adjusting parameters, conditions have been optimized, i.e., 10 wt% mass concentration, 760 Gs magnetic field intensity, and 15 rpm rotating speed. At optimized conditions, the maximum reflection loss of −49.7 dB at 6.6 GHz and the maximum effective bandwidth of 4.9 GHz (10.66–15.56 GHz) are achieved. It is discovered that the maximum reflection loss of the sample treated in a rotating magnetic field is 4.6 and 5.85 times higher than that of the sample treated in static and non-magnetic field conditions, respectively. This work provides a simple and environmentally friendly physical route to modify the macroscopical order degree and enhance the microwave absorption performance of carbon materials.

Keywords

• Magneto-alignment
• Phoenix tree leaves bio-carbon flakes
• Microwave absorption
• Rotating magnetic field
• Static magnetic field