Urchin-Like Ni Microspherical Structure with Enhanced Magnetic Loss for Thin Microwave Absorber at Gigahertz

NANO ◽  
2017 ◽  
Vol 12 (03) ◽  
pp. 1750034 ◽  
Author(s):  
Yuping Sun ◽  
Zhengwu Pan ◽  
Hongming Long ◽  
Siu Wing Or ◽  
S. L. Ho ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Chemical Reduction ◽  
Magnetic Loss ◽  
Synthetic Strategy ◽  
High Anisotropy ◽  
Absorption Performance ◽  
Wet Chemical ◽  
5 Ghz ◽  
Microwave Absorption Performance ◽  
Absorption Measurements

We describe in this report a wet chemical reduction synthetic strategy for synthesizing urchin-like Ni microspherical structures, in which the nanowires self-assembled by Ni nanoparticles with the size of 5–20[Formula: see text]nm are assembled in a radial form from the center to the surface of the spherical oriented arrays. Urchin-like Ni microspherical structures exhibit the strong magnetic natural resonance peak at 7.0[Formula: see text]GHz and superior magnetic loss at 2–18[Formula: see text]GHz, originated from relatively high anisotropy energy of urchin-like shape. Electromagnetic absorption measurements show that the urchin-like Ni microspherical structures possess outstanding microwave absorption performance at 2–18[Formula: see text]GHz. An optimal reflection loss of [Formula: see text]21.98[Formula: see text]dB can be observed at 17.4[Formula: see text]GHz with a matching thickness of 1.4[Formula: see text]mm and the effective absorption (below −10 dB, 90% absorption) bandwidth is 5 GHz (12–17 GHz) with a thickness of 1.7[Formula: see text]mm. The excellent microwave absorption performance may be attributed to the good impedance, large attenuation constant and novel magnetic loss ability.

Hybrids of cobalt nanochains and polyvinylidene fluoride with enhanced microwave absorption performance

RSC Advances ◽  
2016 ◽  
Vol 6 (60) ◽  
pp. 55546-55551 ◽  
Author(s):  
Shu-Qing Lv ◽  
Ya-Fei Pan ◽  
Pei-Bo Yang ◽  
Guang-Sheng Wang
Keyword(s):  
Microwave Absorption ◽  
Polyvinylidene Fluoride ◽  
Chemical Method ◽  
Wet Chemical Method ◽  
Absorption Properties ◽  
Flexible Film ◽  
Absorption Performance ◽  
Wet Chemical ◽  
Microwave Absorption Performance

By using a simple wet chemical method and hot-molding procedure, a kind of flexible film with enhance absorption properties based on binary cobalt nanochains/polyvinylidene fluoride (PVDF) hybrids has been successfully fabricated.

scholarly journals High Efficiency Microwave Absorption Performance of Cobalt Ferrite Microspheres/multi-walled Carbon Nanotube Composites

2021 ◽  
Author(s):  
Hongmei Liu ◽  
Min Zhang ◽  
Kang Hu ◽  
Xiangkai Kong ◽  
Qiang Li ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
High Efficiency ◽  
Magnetic Loss ◽  
Spinel Ferrite ◽  
Impedance Matching ◽  
Relaxation Processes ◽  
Nanotube Composites ◽  
Multi Walled Carbon Nanotubes ◽  
Absorption Performance ◽  
Microwave Absorption Performance

Abstract In this article, spinel ferrite CoFe2O4 and multi-walled carbon nanotubes (MWCNTs) composites are constructed by a facile one-step solvothermal method. The pure phase of CoFe2O4 particles is confirmed by X-ray diffraction patterns. Microstructure analysis demonstrates that monodisperse CoFe2O4 microspheres are wound by MWCNTs. By the introduction of CNTs, there is a significant enhancement in the imaginary part of permittivity (ε″) with the composites. The champion microwave absorption performance can be achieved in the composites by the balance of complex permittivity and permeability. When the mass fraction of CNTs is 3%, a minimum reflection loss (RLmin) of the composites is as high as -46.65 dB at 14.4 GHz at a thin thickness of 1.5 mm, and the corresponding effective absorption bandwidth below − 10 dB reaches 4.91 GHz ranging from 12.41 to 17.32 GHz which covers almost the whole Ku band (12.0–18.0 GHz). In other words, this as-synthesized composites show the most outstanding specific RLmin of -31.1 dB•mm− 1. Such superior microwave absorption behaviors of CoFe2O4/CNTs originate mainly from multiple dielectric relaxation processes, enhanced impedance matching and magnetic loss, as well as the considerable interface between mesoporous CoFe2O4 hollow microspheres and CNTs, and thereby promoting microwave reflection and scattering within the samples. Our results indicate that as-fabricated CoFe2O4/CNTs composites can be a promising microwave absorbent integrating with thin thickness, strong absorption ability, and broad bandwidth absorption.

scholarly journals 3D Seed-Germination-Like MXene with In Situ Growing CNTs/Ni Heterojunction for Enhanced Microwave Absorption via Polarization and Magnetization

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Xiao Li ◽  
Wenbin You ◽  
Chunyang Xu ◽  
Lei Wang ◽  
Liting Yang ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Seed Germination ◽  
Microwave Absorption ◽  
Magnetic Loss ◽  
Impedance Matching ◽  
Matching Condition ◽  
Ni Nanoparticles ◽  
Absorption Performance ◽  
Microwave Absorption Performance

Highlights Benefiting from the possible “seed-germination” effect, the “seeds” Ni2+ grow into “buds” Ni nanoparticles and “stem” carbon nanotubes (CNTs) from the enlarged “soil” of MXene skeleton. Compared with the traditional magnetic agglomeration, the MXene-CNTs/Ni hybrids exhibit the highly spatial dispersed magnetic architecture. 3D MXene-CNTs/Ni composites hold excellent microwave absorption performance (−56.4 dB at only 2.4 mm). Abstract Ti3C2Tx MXene is widely regarded as a potential microwave absorber due to its dielectric multi-layered structure. However, missing magnetic loss capability of pure MXene leads to the unmatched electromagnetic parameters and unsatisfied impedance matching condition. Herein, with the inspiration from dielectric-magnetic synergy, this obstruction is solved by fabricating magnetic CNTs/Ni hetero-structure decorated MXene substrate via a facile in situ induced growth method. Ni2+ ions are successfully attached on the surface and interlamination of each MXene unit by intensive electrostatic adsorption. Benefiting from the possible “seed-germination” effect, the “seeds” Ni2+ grow into “buds” Ni nanoparticles and “stem” carbon nanotubes (CNTs) from the enlarged “soil” of MXene skeleton. Due to the improved impedance matching condition, the MXene-CNTs/Ni hybrid holds a superior microwave absorption performance of − 56.4 dB at only 2.4 mm thickness. Such a distinctive 3D architecture endows the hybrids: (i) a large-scale 3D magnetic coupling network in each dielectric unit that leading to the enhanced magnetic loss capability, (ii) a massive multi-heterojunction interface structure that resulting in the reinforced polarization loss capability, confirmed by the off-axis electron holography. These outstanding results provide novel ideas for developing magnetic MXene-based absorbers.

scholarly journals Microwave Absorption Performance of Graphene Nanoplatelets Dispersed SiC

2019 ◽  
Vol 69 (5) ◽  
pp. 437-441 ◽  
Author(s):  
Anil Kumar Maurya ◽  
Saurabh Mr ◽  
Samarjit Singh ◽  
Abhishek Kumar
Keyword(s):  
Microwave Absorption ◽  
Reflection Loss ◽  
Graphene Nanoplatelets ◽  
Enhanced Absorption ◽  
Microwave Attenuation ◽  
Microwave Signals ◽  
Absorption Performance ◽  
Sic Composites ◽  
5 Ghz ◽  
Microwave Absorption Performance

Microwave absorption performance of graphene nanoplatelets based SiC composites have been studied in the present work. Graphene nanoplatelets were dispersed at varying weight fractions viz. 0.5, 1, 2, 2.5 and 3 wt.% in SiC using ultrasonication and ball milling methods. Microwave attenuation behaviour of the prepared composites have been observed in the 2-18 GHz range. The results reflect that dispersion of graphene in SiC proves to be very instrumental in attenuating the incident microwave signals translating into enhanced absorption. The enhancement in the microwave absorption performance is due to the presence of conductive graphene nanoplatelets which is very instrumental in promoting conduction and polarisation losses in the composite translating into enhanced absorption. For 3 wt.% graphene nanoplatelets dispersion in SiC, the value of reflection loss (RL) was obtained as -38.67 dB at 14.67 GHz frequency for 2.2 mm thickness with the corresponding bandwidth of 5 GHz.

scholarly journals Effect of Reaction Time on Microwave Absorption Properties of Fe3O4 Hollow Spheres Synthesized via Ostwald Ripening

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2921 ◽  
Author(s):  
Wei Huang ◽  
Yujiang Wang ◽  
Shicheng Wei ◽  
Bo Wang ◽  
Yi Liang ◽  
...  
Keyword(s):  
Reaction Time ◽  
Microwave Absorption ◽  
Ostwald Ripening ◽  
Impedance Matching ◽  
Hollow Spheres ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Magnetic Structures ◽  
Absorption Performance ◽  
Microwave Absorption Performance

Hollow magnetic structures have great potential to be used in the microwave absorbing field. Herein, Fe3O4 hollow spheres with different levels of hollowness were synthesized by the hydrothermal method under Ostwald ripening effect. In addition to their microstructures, the microwave absorption properties of such spheres were investigated. The results show that the grain size and hollowness of Fe3O4 hollow spheres both increase as the reaction time increases. With increasing hollowness, the attenuation ability of electromagnetic wave of Fe3O4 spheres increases first and then decreases, finally increases sharply after the spheres break down. Samples with strong attenuation ability can achieve good impedance matching, which it does preferentially as the absorber thickness increases. Fe3O4 hollow spheres show the best microwave absorption performance when the reaction time is 24 h. The minimum reflection loss (RL (min)) can reach −40 dB, while the thickness is only 3.2 mm.

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