Urchin-like Fe3O4@C hollow spheres with core-shell structure: Controllable synthesis and microwave absorption

Meng Wu; Lei Rao; Lu Liu; Yuexia Li; Yuan Zhang; Ziying Ji; Guobing Ying

doi:10.1016/j.jcis.2023.06.077

Urchin-like Fe₃O₄@C hollow spheres with core-shell structure: Controllable synthesis and microwave absorption

J Colloid Interface Sci. 2023 Nov:649:313-324. doi: 10.1016/j.jcis.2023.06.077. Epub 2023 Jun 16.

Authors

Meng Wu¹, Lei Rao², Lu Liu¹, Yuexia Li¹, Yuan Zhang¹, Ziying Ji¹, Guobing Ying³

Affiliations

¹ Department of Materials Science and Engineering, College of Mechanics and Materials, Hohai University, Nanjing 211100, China.
² Department of Materials Science and Engineering, College of Mechanics and Materials, Hohai University, Nanjing 211100, China. Electronic address: raol@hhu.edu.cn.
³ Department of Materials Science and Engineering, College of Mechanics and Materials, Hohai University, Nanjing 211100, China. Electronic address: yinggb2010@126.com.

PMID: 37352562
DOI: 10.1016/j.jcis.2023.06.077

Abstract

The steadily increasing use of microwave stealth materials in aerospace flying vehicles needs the development of lightweight absorbers with low density and high thermal stability for printing or spraying. In that regard, the structural designability of typical microwave absorbers made of Fe₃O₄ seems to be a significant roadmap. In this work, a hollow spherical structure with a uniform carbon shell around the urchin-like Fe₃O₄ core (Fe₃O₄@C) was produced via a two-step hydrothermal method and annealing. The Fe₃O₄@C absorber exhibited a strong minimum reflection loss (RL_min) of -73.5 dB at the matching thickness of 3.23 mm. The maximum effective absorption bandwidth (EAB_max) was 4.78 GHz at 4.55 mm. The proposed urchin-like core-shell structure was shown to provide good impedance matching and electromagnetic loss ability due to the synergistic effect of Fe₃O₄ and C. In particular, the urchin-like structure increases the heterogeneous interfaces and effectively improves their polarization and relaxation. On the other hand, it reduces the density of the absorber and enhances multiple scattering attenuations of electromagnetic waves (EMWs). Therefore, the findings of the present study open up prospects for the design of high-efficiency lightweight microwave absorbers with specialized structures.

Keywords: Core-shell structure; Hydrothermal method; Interface polarization; Microwave absorption; Urchin-like Fe(3)O(4)@C.