Abstract
The magnetic nanoparticle composite NiFe2O4 has traditionally been studied for high-frequency microwave absorption with marginal performance towards low-frequency radar bands (particularly L and S bands). Here, NiFe2O4 nanoparticles and nanohybrids using large-diameter graphene oxide (GO) sheets are prepared via solvothermal synthesis for low-frequency wide bandwidth shielding (L and S radar bands). The synthesized materials were characterized using XRD, SEM, FTIR and microwave magneto dielectric spectroscopy. The dimension of these solvothermally synthesized pristine particles and hybrids lies within 30–58 nm. Microwave magneto-dielectric spectroscopy was performed in the low-frequency region in the 1 MHz-3 GHz spectrum. The as-synthesized pristine nanoparticles and hybrids were found to be highly absorbing for microwaves throughout the L and S radar bands (< −10 dB from 1 MHz to 3 GHz). This excellent microwave absorbing property induced by graphene sheet coupling shows application of these materials with absorption bandwidth which is tailored such that these could be used for low frequency. Previously, these were used for high frequency absorptions (typically > 4 GHz) with limited selective bandwidth.
Highlights
The role of multifunctional materials as absorbers is significant in both antenna engineering and electromagnetic interference shielding/radar absorption
After the vessel temperature returned to room temperature at the completion of reaction, the residue was washed with DI water repeatedly to neutralize the pH and the later heated at 110°C to obtain the powder of NiFe2O4
X-ray diffraction (XRD) was carried out for both the NiFe2O4 nanoparticles and the NiFe2O4rGO hybrid to analyze the structure of the synthesized nanopowder
Summary
The role of multifunctional materials as absorbers is significant in both antenna engineering and electromagnetic interference shielding/radar absorption. Several strategies have been used to minimize the effective radar cross section and decrease the reflection and emissions as well [1,2]. Surface engineering of aerospace structures is considered as an effective tool in reducing radar signatures besides other methods like structural shaping and active and passive loadings [1,3,4,5]. Radar-absorbing coatings have employed different kinds of materials like ceramics, polymers and polymer composites have a pivotal role in surface engineering of aerospace structures [6,7]. Microwave absorber materials are characterized normally based on the absorption mechanism, i.e., dielectric absorbers, magnetic absorber and hybrid materials [8]. Dielectric absorber materials typically involve polymers and their composites, such as epoxy, olefin, polyester, PET
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