Cobalt magnetic particles and carbon composite microtubes as high-performance electromagnetic wave absorbers

Abstract

Two kinds of magnetic particle and cotton-based carbon composite absorbers (PCMT/Co and CMT/Co) were synthesized based on a chemical component and morphology design principle. As confirmed by scanning electron microscopy, CMT/Co has a microtube-like structure, while PCMT/Co has a hierarchically porous microtube-like structure. Co metal particles which are encapsulated in the tubular-structure and the carbon matrix were used to improve the electromagnetic matching condition and bring magnetic loss ability. The porous and hollow structure can reduce the material's density and bring more interfaces. Therefore, through the Debye dipolar relaxation and interfacial polarization-induced dielectric loss together with the exchange resonance-induced magnetic loss, electromagnetic waves can be rapidly attenuated inside PCMT/Co and CMT/Co. At a matching thickness of 1.4 mm, PCMT/Co shows a reflection loss (RL) of −36.8 dB and an effective attenuation bandwidth (EABW, RL < −10 dB) of 6.7 GHz, while CMT/Co achieves a minimum RL value of −31.2 dB and EABW of 5.5 GHz. Considering the preparation procedure and the raw material source, PCMT/Co and CMT/Co may become promising candidates in the field of EMW absorption due to their thin matching thickness, wider bandwidth absorption, low cost and ease of synthesis.