Shamshirgar Ali Saffar, Rojas Hernández Rocio E, Tewari Girish C, Fernández José Francisco, Ivanov Roman, Karppinen Maarit, Hussainova Irina
Department of Mechanical and Industrial Engineering, Tallinn University of Technology, 19086 Tallinn, Estonia.
Department of Chemistry and Materials Science, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.
ACS Appl Mater Interfaces. 2021 May 12;13(18):21613-21625. doi: 10.1021/acsami.1c02899. Epub 2021 Apr 27.
Graphene is currently attracting attention for radiation absorption particularly at gigahertz and terahertz frequencies. In this work, composites formed by graphene-augmented γ-AlO nanofibers embedded into the α-AlO matrix are tested for X-band absorption efficiency. Composites with 15 and 25 wt % of graphene fillers with shielding effectiveness (SE) of 38 and 45 dB, respectively, show a high reflection coefficient, while around the electrical percolation threshold (∼1 wt %), an SE of 10 dB was achieved. Furthermore, based on the dielectric data obtained for varying fractions of graphene-/γ-AlO-added fillers, a functionally graded multilayer is constructed to maximize the device efficiency. The fabricated multilayer offers the highest absorption efficiency of 99.99% at ∼9.6 GHz and a full X-band absorption of >90% employing five lossy layers of 1-3-5-15 and 25 wt % of graphene/γ-AlO fillers. The results prove a remarkable potential of the fillers and various multilayer designs for broad-band and frequency-specific microwave absorbers.
石墨烯目前在辐射吸收方面备受关注，尤其是在吉赫兹和太赫兹频率下。在这项工作中，对嵌入α - AlO基体中的石墨烯增强γ - AlO纳米纤维形成的复合材料进行了X波段吸收效率测试。含有15 wt%和25 wt%石墨烯填料的复合材料，其屏蔽效能（SE）分别为38 dB和45 dB，显示出高反射系数，而在大约电渗流阈值（~1 wt%）时，实现了10 dB的SE。此外，基于不同比例添加石墨烯/γ - AlO填料所获得的介电数据，构建了功能梯度多层结构以最大化器件效率。所制备的多层结构在约9.6 GHz时具有99.99%的最高吸收效率，并且采用1 wt%、3 wt%、5 wt%、15 wt%和25 wt%的石墨烯/γ - AlO填料的五个损耗层实现了全X波段大于90%的吸收。结果证明了这些填料以及各种多层设计在宽带和特定频率微波吸收器方面具有显著潜力。
