关键词: Flower-like NiO/SiCw, Dielectric loss, Interfacial polarization, Microwave absorption

Abstract: Toward the increasingly serious problem of electromagnetic wave pollution, the development of absorbing material with the properties of the light, thin, wide, strong, and multiple applications scenarios is still a huge challenge. Herein, the core-shell nickel oxide/silicon carbide whiskers (NiO/SiCw) with variational NiO morphologies (tulle-, flower, and rod-like) were designed and fabricated via a facile pre-hydrothermal method and post-annealing process. For the NiO shell morphology, it can effectively be controlled by the proportion of Ni(NO₃)₂·6H₂O, NH₄Cl, and CO(NH₂)₂. The structure of NiO/SiCw samples was investigated by XRD, SEM, XPS, TEM, and N₂ absorption-desorption. Compared to other morphologies of NiO, the flower-like NiO/SiCw possess a porous structure and large surface area that can benefit from the multiple reflections and attenuation of the microwave. As an absorber, the composite with the flower-like NiO/SiCw filler loading of 50% manifests a superior microwave attenuation capability due to its special porous structure, good impedance matching, and large dielectric loss induced from heterojunction interfacial polarization. The minimum reflection loss of flower-like NiO/SiCw is up to -56.8 dB with a thickness of 1.9 mm, and the maximum effective absorption bandwidth (EAB) reaches 5.17 GHz. The as-prepared flower-like NiO/SiCw with strong absorption, thin thickness, and width EAB can meet the potential requirements for microwave absorption materials under oxidation environments.

Key words: Flower-like NiO/SiCw, Dielectric loss, Interfacial polarization, Microwave absorption