Microwave absorption performance of porous heterogeneous SiC/SiO₂ microspheres

It is confirmed that the composites with multiple components and plentiful heterogeneous interfaces have been considered as preferred efficient electromagnetic (EM) wave absorbers. The special structure for hollow, porous, and core-shell has good adjustable dielectric properties. Herein, porous heterogeneous SiC/SiO₂ microspheres are prepared based on the self-assembly technology and carbothermal reduction strategy. The structural evolution and composition control of porous heterogeneous SiC/SiO₂ microspheres can be achieved by adjusting the carbothermal reduction temperature. The results indicate that structure and composition have a significant effect on the absorption performance. Especially, when the temperature is 1400 °C, the porous heterogeneous SiC/SiO₂ microspheres exhibit the most excellent EM wave absorption properties; the minimal reflection loss (RL_min) value is −54.68 dB at 8.99 GHz. The maximum effective bandwidth (EAB_max) for RL_min < −10 dB reaches 8.49 GHz, exhibiting absorption capacity in almost all bands (S, C, X, and Ku bands). It can well satisfy the comprehensive requirements of efficient EM wave absorption absorbers for lightweight and broad EAB characteristics. The excellent performance is due to the strong interfacial polarization caused by plentiful heterogeneous interfaces between different phases. Meanwhile, a highly porous structure and SiO₂ phase can regulate complex dielectric constant, leading to better impedance matching. This work provides useful thinking for the design of efficient EM wave absorption absorbers.