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Permittivity-Regulating Strategy Enabling Superior Electromagnetic Wave Absorption of Lithium Aluminum Silicate/rGO Nanocomposites

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journal contribution
posted on 10.04.2019, 00:00 by Siru Lu, Long Xia, Jiaming Xu, Chuheng Ding, Tiantian Li, Hua Yang, Bo Zhong, Tao Zhang, Longnan Huang, Li Xiong, Xiaoxiao Huang, Guangwu Wen
Lithium aluminum silicate (LAS) nanoparticles have been successfully loaded on graphene nanosheets by adding a silane coupling agent KH-550 by sol–gel process, hydrothermal reaction, and heat treatment process. By regulating the complex permittivity of reduced graphene oxide (rGO) by LAS nanoparticles and KH-550, LAS/rGO-KH-550 possesses excellent microwave absorption performance. The maximum reflection loss of LAS/rGO-KH-550 reaches −62.25 dB at 16.48 GHz with thickness of only 2.7 mm, and the widest bandwidth is up to 6.64 GHz below −10 dB. The LAS/rGO-KH-550 has effective absorption (99.9%) below −20 dB at all X and Ku bands (8–18 GHz). Also, the added quantity of composites in the paraffin matrix is only 20 wt %. The results demonstrate that the interfacial polarization, the Debye dipolar relaxation, the well-matched characteristic impedance, and the quarter-wavelength matching all play important roles in improving the microwave absorption properties of LAS/rGO-KH-550 nanocomposites. Consequently, the LAS/rGO-KH-550 nanocomposites can be readily applied as an ultra-wide-band, light weight, and ultra-high-performance microwave-absorbing material.