title: Facile Hydrothermal Synthesis of Fe3O4/C Core-Shell Nanorings for Efficient Low-Frequency Microwave Absorption.
abstract: Using elliptical iron glycolate nanosheets as precursors, elliptical Fe3O4/C core-shell nanorings (NRs) [25 ± 10 nm in wall thickness, 150 ± 40 nm in length, and 1.6 ± 0.3 in long/short axis ratio] are synthesized via a one-pot hydrothermal route. The surface-poly(vinylpyrrolidone) (PVP)-protected-glucose reduction/carbonization/Ostwald ripening mechanism is responsible for Fe3O4/C NR formation. Increasing the glucose/precursor molar ratio can enhance carbon contents, causing a linear decrease in saturation magnetization (Ms) and coercivity (Hc). The Fe3O4/C NRs reveal enhanced low-frequency microwave absorption because of improvements to their permittivity and impedance matching. A maximum RL value of -55.68 dB at 3.44 GHz is achieved by Fe3O4/C NRs with 11.95 wt % C content at a volume fraction of 17 vol %. Reflection loss (RL) values (≤-20 dB) are observed at 2.11-10.99 and 16.5-17.26 GHz. Our research provides insights into the microwave absorption mechanism of elliptical Fe3O4/C core-shell NRs. Findings indicate that ring-like and core-shell nanostructures are promising structures for devising new and effective microwave absorbers.
authors.affiliation: College of Chemistry and Life Sciences, Zhejiang Normal University , Jinhua, Zhejiang 321004, China.|College of Chemistry and Molecular Sciences, Wuhan University , Wuhan, Hubei 430072, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Wu
authors.affiliation: College of Chemistry and Life Sciences, Zhejiang Normal University , Jinhua, Zhejiang 321004, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Liu
authors.affiliation: College of Chemistry and Molecular Sciences, Wuhan University , Wuhan, Hubei 430072, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Zeng
authors.affiliation: College of Chemistry and Life Sciences, Zhejiang Normal University , Jinhua, Zhejiang 321004, China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Cui
authors.affiliation: College of Chemistry and Life Sciences, Zhejiang Normal University , Jinhua, Zhejiang 321004, China.
authors.forename: Yanting
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: College of Chemistry and Life Sciences, Zhejiang Normal University , Jinhua, Zhejiang 321004, China.
authors.forename: Yana
authors.initials: Y
authors.lastname: Li
authors.affiliation: College of Chemistry and Life Sciences, Zhejiang Normal University , Jinhua, Zhejiang 321004, China.
authors.forename: Guoxiu
authors.initials: G
authors.lastname: Tong
keywords: Fe3O4/C; hydrothermal method; magnetic property; microwave absorption; nanoring