Synthesis and Excellent Microwave Absorption Properties of ZnO/Fe₃O₄/MWCNTs Composites

Abstract

ZnO nanocrystals were introduced into Fe 3 O 4 /MWCNTs composites to improve the impedance matching and electromagnetic (EM) wave attenuation of the system. The as-synthesized ZnO/ Fe 3 O 4 /MWCNTs composites were characterized by X-ray di®raction, vibrating sample magnetometer,¯eld-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy. SEM and TEM images showed that Fe 3 O 4 microspheres 100-200 nm in size connected MWCNTs. Analysis of EM parameters revealed that the impedance matching of the ZnO/Fe 3 O 4 /MWCNTs composites was considerably improved after ZnO nanocrystals were introduced. The ZnO/Fe 3 O 4 /MWCNTs composites exhibited a highly e±cient microwave absorption (MA) capacity within the tested frequency range of 2-18 GHz. The optimal re°ection loss of EM waves was À38:2 dB at 6.08 GHz with an absorber thickness of 3.5 mm. The excellent MA properties of the composites could be attributed to the improved impedance matching, interfacial polarization, and combined e®ects of dielectric and magnetic losses.

Two-dimensional materials and one-dimensional carbon nanotube composites for microwave absorption

“…For investigating the microwave absorption performance of MoS 2 and MoS 2 /CNT nanohybrids, MoS 2 or MoS 2 /CNT nanocomposites are mixed with paraffin and then the frequency dependence of the electromagnetic parameters was obtained from the VNA. Figures 4(a The real and imaginary parts of the relative complex permittivity stand for the energy storage ability and the energy dissipation ability of the microwave absorption materials [6,10,17,34]. For pure MoS 2 with a nanoflower structure, there is no distinct undulation of the real (e¢ » 5. )…”

“…An ideal microwave absorber should be broadband, have strong absorption and be lightweight. According to the transmit line theory, the RL frequency dependence of MoS 2 and MoS 2 /CNT nanohybrids can be calculated by the following equations [1,2,17]:…”

“…Microwave absorption performance has been related to structure, which has been illustrated in many studies [14]. As an important member, CNTs have been a research hotspot for microwave absorption in recent years [2,9,[15][16][17][18][19]. The reasons are as following: first, CNTs were the most representative one-dimensional nanomaterials with large specific surface area, high aspect ratio and a large number of dangling keys, which is beneficial for multiple reflections and the relaxation loss of microwaves in CNT networks [20].…”

One‐Pot Hydrothermal Synthesis of Co3O4/MWCNTs/Graphene Composites with Enhanced Microwave Absorption in Low Frequency Band

“…In general, the MAMs include ferrites, metallic oxides, carbon materials and conducting polymer etc. At present stage, ferromagnetic metals (Fe, Co, Ni) and their oxides have been widely investigated for the advantages of strong absorption ability, high efficiency, low cost and so on, e. g. Wu et al .…”

“…Therefore, as a kind of functional material, the microwave absorption materials (MAMs) which can dis-sipate the electromagnetic (EM) by converting the EM radiation energy to heat or other energy have drawn more and more attentions. [1][2][3][4] In general, the MAMs include ferrites, [5][6][7] metallic oxides, [8][9][10] carbon materials [11,12] and conducting polymer [13,14] etc. At present stage, ferromagnetic metals (Fe, Co, Ni) and their oxides have been widely investigated for the advantages of strong absorption ability, high efficiency, low cost and so on, e. g. Wu et al [15] prepped porous CoÀ Co 3 O 4 hybrid hollow spheres via hydrogen reduction.…”