Compositional and morphological design of hierarchical Co2Y@MnO2@CNTs core-shell microflowers for broadband microwave absorption application

摘要

The hexaferrite materials have been regarded as a promising candidate for the advanced electromagnetic wave absorbing (EMA) materials. Meanwhile, the flower-like morphological and hierarchical structure has been widely accepted as a critical technique to achieve both lower reflection loss (RL) and wider qualified bandwidth (QB, RL <= -10 dB) due to the induced multiple scattering and electromagnetic loss abilities for microwave absorption. In this study, core-shell nanostructure composites of Co2Y@MnO2@CNTs have been successfully synthesized by a facile one-step hydrothermal method, in which the Ba2Co2Fe12O22 (Co2Y) nanoparticles are wrapped in the carbon nanotubes (CNTs) attached hollow MnO2 microflowers. Results show that the surface morphology can be well controlled by modulating the mass ratio of Co2Y and MnO2 reactants, and the characteristic impedance can be greatly improved through the precise tuning of the conductive CNTs attachments. An ultra-wide QB value of 15.7 GHz (2.3-18 GHz) is realized within an integrated thin thickness from 1.0 to 5.0 mm, which means the composite shows excellent EMA performance in the S, C, X, and Ku band with relatively thin sample thicknesses. For example, the RLmin reached -22.6 dB at 12.6 GHz with a QB of 7.22 GHz at 1.63 mm in the Ku band, and -40.4 dB at 3.28 GHz with a QB of 3.47 GHz at 4.87 mm in the S and C band. Besides the outstanding microwave absorbent candidates, this work has also developed a novel and more generalized approach to promoting the ferrite-based high-performance EMA application by delicate nanostructure and composition design. (C) 2021 Elsevier B.V. All rights reserved.