Hierarchical structured ZnFe2O4@SiO2@RGO core–shell nanocomposites were prepared via a “coating–coating” route, and its structure, composition and electromagnetic properties were characterized. Compared with the binary composites of ZnFe2O4@SiO2, the hierarchical ZnFe2O4@SiO2@RGO ternary composites exhibited enhanced electromagnetic wave (EMW) absorption properties in terms of the effective bandwidth and minimum reflection loss (RL). Furthermore, EMW absorption properties of the prepared samples can be tuned by changing RGO content and thickness of SiO2 layer to reach the best impedance match. The minimum RL of the sample with a thickness of 2.8 mm can reach −43.9 dB at 13.9 GHz, and its effective bandwidth (RL ≤ −10 dB) was up to 6 GHz. Hence, the obtained products can be a new candidate for lightweight EMW absorbing materials.
One-dimensional (1D) ZnFe 2 O 4 @SiO 2 (ZS) nanochains were prepared with Stöber method under external magnetic field. Then, 1D ZS nanochains were covered with a uniform polydopamine (PDA) shell, and the pyrolysis process was completed to obtain 1D ZnFe 2 O 4 @SiO 2 @C (ZSC) nanochains. Finally, 1D flower-like ZnFe 2 O 4 @SiO 2 @C@NiCo 2 O 4 (ZSCNC) nanochains were fabricated through a simple hydrothermal method. The carbon layer with strong dielectric loss enabled the 1D ZSC nanochains to achieve an ultra-wide effective absorption bandwidth (EAB) of 6.22 GHz. Compared with the above nanochains, the 1D ZSCNC nanochains showed more excellent microwave absorption (MA) properties because of the unique 1D flower-like architectures having large surfaces and multiple interfaces. The sample loaded with 30 wt% 1D flower-like ZSCNC nanochains showed strong MA performances with a minimum reflection loss (RL) value of −54.29 dB (11.14 GHz) and an EAB of 5.66 GHz (11.94–17.60 GHz) at the thickness of 2.39 mm. The 1D flower-like ZSCNC nanochains with strong absorption, broad absorption bandwidth (almost the entire Ku band) and thin layer has a good application prospect for the absorption of electromagnetic waves in Ku band.
Boshuo Shi,Bo Wang,Qing Han,Shicheng Wei,Yujiang Wang,Kuiren Liu,Jianshe Chen,Daxue Fu,Binchuan Li
Constructing a reasonable dielectric-magnetic synergistic effect is an effective way to prepare high-performance electromagnetic wave absorbers. In this paper, ZnFe2O4@SiO2/C composites with a close-packed structure were successfully synthesized by an efficient condensation reaction of a silane coupling agent and high-temperature mechanochemical technology. The silane coupling agent can effectively adjust the occurrence state of ZnFe2O4 and the graphite interlayer compound, so as to realize the adjustable electromagnetic parameters. When the ratio of silane coupling agent, deionized water, and anhydrous ethanol is 1:1:1, ZnFe2O4@SiO2/C composites achieve a minimum reflection loss value (RLmin) of −52.5 dB at a thickness of 1.87 mm and a maximum effective absorption bandwidth (EABmax) of 4.16 GHz at a thickness of 2.07 mm. In addition, the EAB covers 8–12 GHz at a thickness of 1.97 mm, achieving efficient absorption of X-band electromagnetic waves. Through the optimization of structure and composition, the problems of large thickness and limited electromagnetic wave performance of ZnFe2O4/C composites are effectively improved, which provides a way for the design and large-scale preparation of ZnFe2O4-based absorbers with high electromagnetic wave absorption performance in the X-band.
危险品化学品经营许可证（带存储）