Dielectric gradient C@SiC@SiO2 microspheres for broadband room-temperature microwave absorption

Triple-layered C@SiC@SiO 2 microspheres were successfully fabricated. • Superb RL of −62.95 dB and 3.05 GHz bandwidth are achieved at thinness. • Gradient impedance structure boosts wave penetration and attenuation. Gradient structural engineering holds great promise in boosting microwave absorption capability by realizing smooth impedance matching and manipulating electromagnetic wave transportation within materials. Herein, well-defined triple-layered C@SiC@SiO 2 microspheres with a dielectric gradient architecture are rationally constructed via hydrothermal self-assembly followed by carbothermal reduction. By delicately regulating the composition ratio of C/SiC/SiO 2 , the optimized absorber achieves outstanding room-temperature microwave absorption properties: a minimum reflection loss (RL min ) of −62.95 dB at a thin thickness of 1.73 mm, and a broad effective absorption bandwidth (EAB max) of 3.05 GHz (RL < −10 dB) at merely 1.68 mm, which covers the most of the X-band. The excellent absorption performance is synergistically contributed by the significantly optimized impedance matching originating from the three-layer dielectric gradient architecture, abundant heterogeneous interfaces inducing intense interfacial polarization, as well as rich dipoles favoring strong dipole polarization. Moreover, the gradient structure also promotes multiple scattering and reflection of electromagnetic waves, further enhancing energy attenuation. This work not only develops a high-performance microwave absorber but also offers a feasible strategy for designing gradient heterostructures toward advanced electromagnetic wave absorption applications. Download: Download high-res image (130KB) Download: Download full-size image