Dual nonlinear dielectric resonance and nesting microwave absorption peaks of hollow cobalt nanochains composites with negative permeability

Abstract

The permittivity and permeability behaviors of the hollow cobalt nanochains composites have been investigated in 2–18 GHz. The permittivity presents two dielectric resonance peaks at about 12.3 and 14.5 GHz, respectively, which mainly results from the cooperative consequence of the hollow structure and the one-dimensional structure of the as-synthesized Co nanochains. The negative permeability behavior within 12.3–18 GHz is attributed to radiation of the magnetic energy according to the as-established equivalent circuit model. Two strong absorption peaks of the composites nest at the resonance frequencies due to the effect of the dual nonlinear dielectric resonance and the negative permeability behavior.

Analyses on multiple resonance behaviors and microwave reflection loss in magnetic Co microflowers

“…The second resonance peak at 11.2 GHz is close to the resonance frequency reported in Ref. [13]. The third peak at 14.96 GHz is consistent with the resonance frequencies reported in hollow cobalt nanochains [13] and carbon-coated Sn nanorods [14].…”

Titanium Dioxide/Multi-Walled Carbon Nanotube Heterostructure Containing Single One Carbon Nanotube and Its Electromagnetic Properties

“…Figure 4(a) shows the RL of the MWCNT/para±n, TiO 2 /para±n and TiO 2 @MWCNT/para±n. Generally, the RL for bare MWCNT is relatively strong in X band 17 (8)(9)(10)(11)(12) and Ku band 18 (12)(13)(14)(15)(16)(17)(18), similar phenomenon has been reported by Kshirsagar and Sharon et al 19 A strong peak can be observed at about 12 GHz and a relatively strong absorption can be observed throughout the Ku band. Besides, the RL for bare TiO 2 is weak throughout the whole frequency range, even the peak value at 15 GHz is less around À7.5 dB.…”

“…3) is put forward to simulate this process. 14 It is found in Fig. 3(d) that the curve of " 00 versus " 0 exhibits a dielectric cole-cole semicircle plot.…”

Response to “Comment on ‘The electromagnetic property of chemically reduced graphene oxide and its application as microwave absorbing material’” [Appl. Phys. Lett. 100, 046101 (2012)]

“…[3][4][5][6][7][8] Nobody can give a convincing interpretation for the negative l 00 , Deng and Han 3 explain the phenomenon as the magnetic energy being radiated out, Chiu et al 7 point out it is meaningless and might be due to noise, while Chen et al 8 point out it does not arise from test error and needs further study. The electromagnetic parameters are determined via HP-5783E vector network analyzer, a sample containing 60 wt.…”

“…Watts et al 12 have reported that defects can act as polarized centers, so the defects and groups may result in relaxation under alternated field. Most published papers present the absorption at 2 mm or near to 2 mm, [3][4][5][6][7][8][9][10] therefore, we only give the absorption of r-GO at 2 mm in Ref. 1 just for the convenience of comparison.…”