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Key Words:Fluorine compounds;Bandwidth - Carbon nanofibers - Dielectric losses - Manganese oxide - Microwaves - Oxides - Shells (structures)
Abstract:Microwave absorption materials have drawn significant attention due to their potential application in information safety and military stealth. In this work, we report a facile strategy to synthesize carbon nanofiber/MnO<inf>x</inf> core-shell composites (CNF@MnO<inf>x</inf>) in order to collaborate their advantage for high-performance microwave absorption application. Through a simple ozone pretreatment process, ultrathin MnO<inf>x</inf> nanoflakes can be uniformly coated onto CNFs by a hydrothermal method. The mixture of several MnO<inf>x</inf> forms coexists in CNF@MnO<inf>x</inf> composites because of the readily available crystalline phase transformation from different manganese oxides. The investigation of microwave absorption properties shows that the absorbing capabilities CNF@MnO<inf>x</inf> composites have significant improvement compared to the pure CNFs and most of single-phase manganese oxides. The minimum reflection loss for CNF@MnO<inf>x</inf> can arrive at −47.2 dB at 9.4 GHz with a thickness of 2.8 mm, and the widest effective absorption bandwidth was measured to be 5.0 GHz. Furthermore, polymorphic MnO<inf>x</inf> endows CNF@MnO<inf>x</inf> with selective-frequency microwave absorption. The dramatic enhancement of microwave absorption is ascribed to dielectric loss, magnetic loss, impedance matching and geometrical effect. Hence, the present CNF@MnO<inf>x</inf> may be a capable candidate for strong-absorption, broadband and lightweight microwave absorber.<br/> © 2019 The Authors
Volume:183
Issue:
Translation or Not:no