Enhanced electromagnetic wave absorption performance of novel carbon-coated Fe₃Si nanoparticles in an amorphous SiCO ceramic matrix

Tunable electromagnetic properties and excellent thermo-stability are important criteria while choosing absorbers. Here, carbon-coated Fe₃Si nanoparticles in amorphous SiCO ceramics (SiCO/C/Fe₃Si) were successfully obtained via polymer-derived ceramics (PDC) from ferric acetylacetonate modified-polysilylacetylene (PSA). By adjusting the magnetic components, the structure of the absorbers could be tuned and their bandwidth varied. The absorbers with a hybrid composition (4.35 wt% Fe) possessed a minimal reflection loss (RL) of -32 dB at 9.2 GHz with a thickness of 3.5 mm and an effective bandwidth (RL < -10 dB) of about 3.6 GHz. The absorbers (12.33 wt% Fe) were enhanced and the minimal RL value was close to -41 dB at 7.9 GHz with a thickness of 3.5 mm. Simultaneously, a broad bandwidth (RL < -5 dB) appeared and covered nearly the whole S-band (2-3.95 GHz) where the RL value reached -10 dB at 2 GHz. After the second thermal treatment under 1000 °C, the minimal RL value of the absorbers (12.33 wt% Fe) remained at -33 dB at 6.6 GHz with a thickness of 4 mm, while the effective bandwidth was 3.4 GHz with a thickness of 3 mm. In addition, the formation mechanism of carbon-coated Fe₃Si, which possibly resulted from the mesophase SiCFe alloy was also discussed. The as-prepared SiCO/C/Fe₃Si hybrid exhibits outstanding wave absorption ability and present a huge potential for the application at high temperatures.