Low-temperature preparation of core–shell SiC@C nanospheres toward electromagnetic wave absorption

Abstract

Spherical materials with a core–shell structure can effectively improve the impedance matching characteristics and dispersity in the matrix. Herein, SiC@C nanospheres with a core–shell structure were prepared by a magnesiothermic reduction reaction at a low temperature (<700 °C), in which in situ formed SiC nanograins were confined in a carbon shell, producing a regular core–shell structure and abundant SiC–C heterogeneous interfaces. The optimized SiC@C nanospheres with a filling ratio of 15 wt% in paraffin concurrently displayed a minimum reflection loss (RL, dB) of −54.38 dB and an effective absorption bandwidth (EAB, RL < −10 dB) of 5.2 GHz at 2.0 mm, at which both strong absorption and broadband characteristics could be achieved simultaneously. The remarkable electromagnetic (EM) absorption performance was ascribed to the core–shell structure and abundant SiC–C heterogeneous interfaces resulting in good impedance matching. This work provides strategies for the design and development of high-performance EM wave absorbing materials.