Single-source-precursor derived SiOC ceramics with in-situ formed CNTs and core–shell structured CoSi@C nanoparticles towards excellent electromagnetic wave absorption properties

Abstract

In this work, novel CNTs/CoSi/SiOC nanocomposite ceramics with<em> in-situ </em>formed multi-walled carbon nanotubes (CNTs) and core-shell structured CoSi@C nanoparticles were successfully prepared <em>via</em> a single-source-precursor derived ceramic approach. The polymeric precursor characterization as well as phase evolution, microstructure and electromagnetic wave (EMW) absorption properties of the ceramics was investigated in detail. The results show that the <em>in-situ</em> formed CNTs and magnetic CoSi@C nanoparticles provide a synergistic effect on both dielectric loss and magnetic loss, leading to outstanding EMW absorption properties of the ceramics annealed at only 1100 °C, as follows: 1) For the Co feeding 6.25 wt.%, the minimum reflection loss (RLmin) is -53.1 dB and the effective absorption bandwidth (EAB) is 4.96 GHz (7.12-12.08 GHz) with a ceramic-paraffin hybrid sample thickness of 3.10 mm, achieving the full X-band coverage; 2) For the Co feeding 9.09 wt.%, the RLmin value of -66.4 dB and the EAB value of 3.04 GHz (8.4-11.44 GHz) were achieved with a thickness of only 2.27 mm. Therefore, the present CNTs/CoSi/SiOC nanocomposite ceramics have potential applications for thin, lightweight and efficient EMW absorption in harsh environments.