2, Korea University, Seoul, , Korea (the Republic of)
3, Amity University, Dubai, , United Arab Emirates
4, Minotech, Charlton, Massachusetts, United States
5, North Carolina State University, Raleigh, Indiana, United States
Recently, reduction and cancellation technology of microwave has been widely studied in military and civil areas for various applications such as radar absorption, electromagnetic interference (EMI) shielding, reduction of electromagnetic wave pollution, and wireless communication fields. Research on microwave absorption materials is widely conducted by adopting dielectric and magnetic powder material to conductive matrix, because the conductivity, dielectric constant and permeability of the materials are contributing to the microwave absorption efficiency of the materials. [1-3]
Carbon nanotubes (CNT) are good candidate materials for the conductive matrix of microwave absorption composite structures due to their high electrical conductivity, light weight, and easiness to form thin layers. Ferrite nanostructures are generally used for microwave absorbing materials due to their magnetic and dielectric property. The electromagnetic properties of ferrites are different depending on microstructural and physical properties of the ferrites such as chemical composition, crystal structure, crystallite size, particle size. Such properties can be controlled by synthesis techniques and our novel synthesis method of multi-granule nanocluster (MGNC) of magnetite (Fe3O4) by controlling the cluster and granule size with the modified hydrothermal polyol process was previously reported .
In this study, we fabricated Fe3O4 MGNC – multiwall CNT (MWCNT) composites by using the surface-engineered tape-casting (SETC) method with various granule and particle size of MGNCs. The microstructural and microwave absorption properties in X-band (8.2 GHz – 12.4 GHz) with different granule size of the nanoclusters are investigated. Design and three-dimensional (3D) printing of the 3D metamaterials based on the nanocomposite materials made up of MGNC and MWSNT are also in progress.
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 J.W. Yi, S.B. Lee, D.G. Seong, S.K. Lee, K.H. Kim, O.O. Park, Effect of iron-deposited graphene oxides on the electromagnetic wave absorbing property of polymer composite films with Fe-based hollow magnetic fibers for near-field applications, Journal of Alloys and Compounds, 663 (2016) 196-203.
 J.S. Lee, J. Myung Cha, H. Young Yoon, J.K. Lee, Y.K. Kim, Magnetic multi-granule nanoclusters: A model system that exhibits universal size effect of magnetic coercivity, Sci Rep, 5 (2015) 12135.