Enhanced Absorption Performance of Carbon Nanostructure Based Metamaterials and Tuning Impedance Matching Behavior by an External AC Electric Field

Abstract

Metamaterials have surprisingly broadened the range of available practical applications in new devices such as shielding, microwave absorbing, and novel antennas. More research has been conducted related to tuning DNG frequency bands of ordered or disordered metamaterials, and far less research has focused on the importance of impedance matching behavior, with little effort and attention given to adjusting the magnitude of negative permittivity values. This is particularly important if devices deal with low-amplitude signals such as radio or TV antennas. The carbon/hafnium nickel oxide (C/HfNiO) nanocomposites with simultaneously negative permittivity and negative permeability, excellent metamaterial performance, and good impedance matching could become an efficient alternative for the ordered metamaterials in wave-transparent, microwave absorbing, and solar energy harvesting fields. In this study, we prepared C/HfNiO nanocomposites by the solvothermal method, and we clarified how the impedance matching and double-negative (DNG) behaviors of C/HfNiO can be tuned by an external AC electric field created by an electric quadrupole system. An external electric field allows for the alignment of the well-dispersed nanoparticles of carbon with long-range orientations order. We believe that this finding broadens our understanding of moderate conductive material-based random metamaterials (MCMRMs) and provides a novel strategy for replacing high-loss ordered or disordered metamaterials with MCMRMs.

Radio‐frequency negative permittivity in the graphene/silicon nitride composites prepared by spark plasma sintering

“…The f p is well corresponding to the frequency points of the positive‐negative transitions for Z ″ (Figure ), and negative ε′ appeared together with an inductive character ( Z ″ > 0). Similar phenomenon was also observed in many random ceramic composites . Hence it is considered that the inductive behavior is a characteristic of negative ε′ .…”

“…However, those materials have some weakness, such as chemical instability and huge negative permittivity . To overcome these restrictions, some studies were recently devoted to realize the negative permittivity in carbon/ceramic composites consisting of carbon nanotube, carbon fiber or amorphous carbon . The good chemical stability and low negative permittivity magnitude makes these composites better apply in the electromagnetic fields .…”

“…To overcome these restrictions, some studies were recently devoted to realize the negative permittivity in carbon/ceramic composites consisting of carbon nanotube, carbon fiber or amorphous carbon . The good chemical stability and low negative permittivity magnitude makes these composites better apply in the electromagnetic fields . Two‐dimensional graphene (GR) can be identified as an ideal candidate for constructing random metamaterials, due to its intrinsic plasmons, tunable electrical conductivity, high tensile strength, and excellent thermal property .…”

Negative permittivity in titanium nitride‐alumina composite for functionalized structural ceramics

“…42 Similarly, negative dielectric behavior was also observed in some cermets and polymer composites. 4,[16][17][18]22,43 Moreover, negative permittivity with plasma character can be described by the following Drude model 44 and the solid lines in Figure 4B were fitted with Equation (2). where ω p (=2πf p ) is angular plasma frequency, γ is a damping term representing dissipation of plasmon's energy to the system, i is the pure imaginary unit, ε 0 (=8.85 × 10 −12 F/m) is vacuum dielectric constant, e (=1.6 × 10 −19 C) is electron charge, n and m eff is the electrons density and effective weight.…”

“…In view of this, it would be novel electromagnetic attenuation materials if the impedance matching could be achieved. 22…”