Hierarchical waxberry-like V2O3@Co/Co3O4/Ni absorbers with remarkable microwave absorption via regulation of magnetic and dielectric loss

The design of microwave absorbers with hierarchical architectures are garnering increasing attention, but the regulation of the dielectric/magnetic loss remains a challenge. Herein, waxberry-like V2O3@Co/Co3O4/Ni (VCN-x) absorbers are fabricated by hydrothermal and annealing process, with magnetic Co/Co3O4/Ni uniformly riveted on the surface of V2O3 microspheres. The morphological evolution of Co/Co3O4/Ni, including nanoparticles, nanosheets, and nanoflowers, was modified by introducing different content of Co and Ni particles. This enrichment the multiple heterogeneous interfaces leads to an enhancement in interfacial polarization. This enhancement is attributed to the internal core-double shell structure, abundant intrinsic defects, and multiple interfaces, VCN-x absorbers exhibit remarkable microwave absorption (MA) performance and a broad effective absorption band (EAB). The enrichment of multiple heterogeneous interfaces leads to an enhancement in interfacial polarization. This enhancement is attributed to the internal core-double shell structure, the presence of abundant intrinsic defects, and the existence of multiple interfaces within VCN-x absorbers. As a result of these structural characteristics, VCN-x absorbers demonstrate exceptional MA performance and exhibit a broad EAB. At a thickness of 2.26 mm, the minimum reflection loss (RLmin) is −59.6 dB. By varying the matching thickness between 1.60 mm and 2.26 mm and by adjusting the EAB from 3.8 GHz to 6.8 GHz, the EAB of VCN-x absorbers can encompass the CKu band.