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Here, we report a facile hydrothermal synthesis method to prepare BiFeO3 nanowire-reduced graphene oxide (BFO-RGO) nanocomposites. The unique properties of 2-D reduced graphene oxide (RGO) and 1-D BiFeO3 nanowires (BFO) were exploited to design nanocomposites to obtain high performing microwave absorber materials. The composite with 97 wt % BFO and 3 wt % RGO exhibited minimum reflection loss value of −28.68 dB at 10.68 GHz along with the effective absorption bandwidth (≥ −10 dB) ranging from 9.6 to 11.7 GHz when the absorber thickness was only 1.55 mm. First-principles calculations based on density functional theory (DFT) of BFO, graphene, and BFO-RGO nanocomposites were performed to obtain information about their electronic structures to interpret their complex permittivity and its derived properties. To the best of our knowledge, this is the first time investigations on microwave absorption properties of the BiFeO3 nanowire and BFO-RGO nanocomposites have been reported, and this nanocomposite shows its potential to be used as a lightweight, high performing microwave absorber in the X-band region.

Here, an ‘in situ’ co-precipitation reaction method has been reported for the preparation of CoFe2O4–RGO (CF–RGO) nanocomposites.

A Ni0.8Zn0.2Fe2O4 reduced graphene oxide nanocomposite has been synthesized by a simple ‘in situ co-precipitation’ technique.

CoFe2O4 nanoparticles, synthesized via a co-precipitation method at 120 °C, exhibited excellent microwave absorption properties, with minimum reflection loss of −55 dB (∼99.99%) at 9.25 GHz.

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Abstract-In this paper, studies on broadband microwave absorption and electromagnetic shielding effectiveness are reported in flexible rubber composites with low filler content of nanosize conducting carbon over 8-18 GHz frequency range of electromagnetic spectrum. Rubber based composites are prepared by loading of 1-15 wt% nanosize conducting Carbon Black (CB) in silicone rubber matrix. Effect of percentage loading of nanosize CB on DC conductivity, dielectric & microwave absorption properties and electromagnetic Shielding Effectiveness (SE) of silicone rubber composites is studied. The percolation threshold is achieved at low concentration (3 wt%) of CB in composites. The observed complex permittivity values revealed that composites with concentration of 5 wt% CB can provide more than 90% microwave absorption (Reflection Loss > −10 dB) over 8-18 GHz at composite thickness of 1.9-2.7 mm. Further, composites with concentration of 15 wt% of CB shows −40 dB SE over the broad frequency range 8-18 GHz at thickness 2.8 mm. The effect of composite thickness on microwave absorption properties and shielding effectiveness is also analyzed. Thus, the prepared rubber composites with suitable concentration of nanosize CB as filler may be used as microwave absorber in stealth applications as well as for EMI shielding of electronic equipments in various civilian and military areas.

Tetragonal BaTiO 3 bulk samples are prepared using the solidstate route in conjunction with intermediate high-temperature annealing steps. The (002) and (200) X-ray diffraction peaks near 2Ɵ~45°and 310, 520, and 720 cm -1 characteristic vibrational modes in Raman spectroscopic measurements confirm the tetragonal crystallographic structure of BaTIO 3 bulk samples. The 1100°C annealed BaTiO 3 sample showed optimal tetragonality~1.016 and the same is used for BaTiO 3 -acrylonitrile butadiene rubber (NBR) composites at different BaTiO 3 loading fractions in parts per hundred (PHR). These BaTiO 3 /NBR composite systems exhibit dual band microwave resonance, widening the operating window for microwave absorption applications. Eighty PHR BaTiO 3 /NBR composite exhibits microwave reflection losses (RL) at 9.5 and 16.5 GHz with~-9 and~-18 dB reflection losses, respectively. The onset of dual band is attributed to the ferroelectric-induced dipolar relaxation at 9.5 GHz and its second-order resonance at 16.5 GHz in such composite systems.