Shell Thickness-Dependent Microwave Absorption of Core–Shell Fe3O4@C Composites
Top Cited Papers
- 22 July 2014
- journal article
- research article
- Published by American Chemical Society (ACS) in ACS Applied Materials & Interfaces
- Vol. 6 (15), 12997-13006
- https://doi.org/10.1021/am502910d
Abstract
Core–shell composites, Fe3O4@C, with 500 nm Fe3O4 microspheres as cores have been successfully prepared through in situ polymerization of phenolic resin on the Fe3O4 surface and subsequent high-temperature carbonization. The thickness of carbon shell, from 20 to 70 nm, can be well controlled by modulating the weight ratio of resorcinol and Fe3O4 microspheres. Carbothermic reduction has not been triggered at present conditions, thus the crystalline phase and magnetic property of Fe3O4 micropsheres can be well preserved during the carbonization process. Although carbon shells display amorphous nature, Raman spectra reveal that the presence of Fe3O4 micropsheres can promote their graphitization degree to a certain extent. Coating Fe3O4 microspheres with carbon shells will not only increase the complex permittivity but also improve characteristic impedance, leading to multiple relaxation processes in these composites, thus the microwave absorption properties of these composites are greatly enhanced. Very interestingly, a critical thickness of carbon shells leads to an unusual dielectric behavior of the core–shell structure, which endows these composites with strong reflection loss, especially in the high frequency range. By considering good chemical homogeneity and microwave absorption, we believe the as-fabricated Fe3O4@C composites can be promising candidates as highly effective microwave absorbers.Keywords
Funding Information
- China Postdoctoral Science Foundation (2013M541394)
- Harbin Institute of Technology (HIT.BRETIII.201223)
- National Natural Science Foundation of China (21003029, 21101041, 21371039)
- Fundamental Research Funds for the Central Universities, China (B201411)
- Natural Science Foundation of Heilongjiang Province (B201405)
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