Abstract:

Metacomposites' high dependence on components and percolation structures leads to an overly large regulation amplitude of negative electromagnetic (EM) parameters. This work designed a FeCo@C functional phase synthesized by electrospinning process based on a biomimetic structure similar to peanuts, and combined it with conductive polyaniline (PANI) to form a set of content gradient metacomposites. These metacomposites have successfully achieved an extremely weak epsilon-negative response (-100 < ε' < 0) in the whole 10 kHz–50 MHz frequency band. Thanks to this peanut-like derived structure of carbon-coated metal, the high plasmonic oscillation intensity of the metal is effectively limited. The filling insensitivity of these metacomposites is manifested as the epsilon-negative spectra remaining basically unchanged throughout the entire frequency band with adjusting FeCo@C content from 2 wt% to 12 wt%. The metacomposites' multi-level interfaces also connect the electron-hole double carrier conductance and the intra-chain electron jumps and inter-chain carrier transitions of the conjugated PANI to jointly construct a three-dimensional conductive network. Correspondingly, their loss tangent angles (tanδ < 0.2) are also significantly reduced compared to metal-matrix metacomposites. Further impedance analysis revealed the intrinsic inductance of the epsilon-negative FeCo@C/PANI metacomposites. Finally, we conducted EM simulation on the scattering ability of EM waves of this magnetic metacomposites and explored its applications in stealth devices, anti-EM interference, and sensitive antennas.

Key words: Metacomposites, Negative permittivity, Bionic structure, Electromagnetic shielding