Synthesis and Microwave-Absorbing Properties of Al₂O₃ Coated Polyhedral Fe Nanocapsules Prepared by Arc-Discharge Method

Abstract

Al2O3coated polyhedral Fe nanocapsules were prepared by arc-discharging a Fe-Al(8at%Al) alloy. High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy, and network analyzer were employed to investigate the microstructures, compositions and electromagnetic properties (2-18GHz). The reflection loss R(dB) of the nanocapsules reaches to -50.5dB at 7.9GHz with a 3mm thickness, and EM absorption properties(RL<-20dB) in the 5.2~16.1GHz range with thickness range of 1.67-4.7mm. The excellent Microwave-absorption properties of as-prepared nanocapsules are ascribed to shape anisotropy and core/shell structure.

Iron-containing nanomaterials: synthesis, properties, and environmental applications

“…Al 2 O 3 coated polyhedral Fe nanocapsules were prepared by arc-discharging a Fe-Al (8 atom% Al) alloy. 110 In addition, mobilization and deposition of iron nano and sub-micrometer particles (INSMP) in a porous medium were investigated using a water-saturated glass micromodel. 111 It was shown that there were dense aggregations at the pores as the concentration of INSMP increased.…”

Microwave absorption behaviour of MWCNT based nanocomposites in X-band region

“…both dielectric and magnetic component is a wellconsidered topic in the field of EMI shielding and RAMs [13][14][15][16][17][18]. As the electromagnetic radiation has both dielectric and magnetic component, so it is obvious that both dielectric and magnetic material is effective for the absorption of microwave radiation.…”

Enhanced dielectric loss induced by the doping of SiC in thick defective graphitic shells of Ni@C nanocapsules with ash-free coal as carbon source for broadband microwave absorption

“…Similar to the permittivity curves, the tanδ ε of the Ni@C A nanocapsules exhibits red shift and tanδ µ stands for magnetic loss ability. Generally speaking, the magnetic loss is mainly composed of domain loss, hysteresis loss, eddy current loss and natural resonance loss [3][4][5][6][7][8][9][10][11][12][13]. The magnetic field in the EM wave is too weak to reduce hysteresis; therefore, the hysteresis loss should not be considered.…”

“…Nanocapsules-in which the magnetic nanostructure works as a core and the dielectric material acts as a shell-can effec tively enhance thermal stability, improve the electron trans port properties, optimize EM absorption performance, and colligate the magnetic characteristics of the integral materials [8]. Compared with oxides (SiO 2 , ZnO, CuO and Al 2 O 3 ) and conductive polymer, carbonaceous materials have proved to be potential candidates for EM absorbers, due to their high performance compared to cost, low density, good thermal sta bility and excellent corrosion resistance [8][9][10][11][12][13]. Among the carbonaceous candidates, onionlike carbon (OLC) is com posed of a concentric graphite layer with interplane distance of 0.34 nm.…”