Enhanced absorption bandwidth in carbon-coated supermalloy FeNiMo nanocapsules for a thin absorb thickness

Large Scale Synthesis of Superparamagnetic Face-centered Cubic Co/C Nanocapsules by a Facile Hydrothermal Method and their Microwave Absorbing Properties

“…The FCC-Co/C nanocapsules-paraffin composite was prepared by uniformly mixing FCC-Co/C nanocapsules with paraffin, and the detailed descriptions can be found elsewhere [7][8][9][10][11] . The mixture was compressed into a cylinder-shaped compact, and then cut into a toroidal shape with 7.00 mm outer diameter and 3.04 mm inner diameter.…”

“…In addition, there are no detectable peaks for carbon in the XRD pattern, indicating the amorphous state of the C shells in the composite. Furthermore, since C is on the shell of the nanocapsules, it is also difficulty to detect its XRD pattern because of breaking down of the periodic boundary condition (translation symmetry) along radial direction 7 . The inset of Figure 1 shows the Raman spectrum of the products, which can provide more detailed information about the structure of the carbon 14 .…”

“…The core-shell structure improves the impedance matching between the nanostructures and the incident microwaves due to the coupling of the electromagnetic field with both the magnetic core and the dielectric shell. Some nanocapsules of this type, including FeNiMo/C, Fe/ZnO, FeCo/Al 2 O 3 , Ni/Cu oxides, etc., have been studied [7][8][9][10] . The ferromagnetic resonance and dielectric resonance of nanocomposite, essential for enhanced microwave absorption, is determined by a few physical parameters of the nanocomposites, namely, anisotropy coefficient K, damping parameter α, saturation magnetization M S , and particle shape 1 .…”

Synthesis, Characterization and Electromagnetic Properties of SnO-coated FeNi Alloy Nanocapsules

“…For carbon-coated iron nanocapsules, the absorption range for exceeding -10 dB is in 2-18 GHz for the absorber thickness of 1.54-7.50 mm and an optimal RL of -43.5 dB was reached at 9.6 GHz with an absorber thickness of 3.1 mm 12 . It is known that FeNi alloys as a kind of important soft-magnetic materials have been widely applied in the field of electronic devices and industry, in which the permalloys with nominal composition Ni81Fe19 (wt%) processes the highest permeability 13 . Liu et al synthesized a series of carbon-coated FeNi alloy nanocapsules and investigated the relationship between EM properties and microstructure in detail 9,[13][14][15] .…”

“…It is known that FeNi alloys as a kind of important soft-magnetic materials have been widely applied in the field of electronic devices and industry, in which the permalloys with nominal composition Ni81Fe19 (wt%) processes the highest permeability 13 . Liu et al synthesized a series of carbon-coated FeNi alloy nanocapsules and investigated the relationship between EM properties and microstructure in detail 9,[13][14][15] . The reflection loss (RL) in carbon-coated FeNi nanocapsules by arc discharging a Fe 90 Ni 10 ingot exceeds -10 dB in the whole Ku-band for an absorber thickness of 2 mm 14 .…”