Two‐dimensional Ti3C2Tx/poly(vinylidene fluoride) metacomposites with weakly negative permittivity. Issue 5 (3rd January 2020) - Zhang, Yuliang
Abstract: In recent years, random metacomposites with tunable negative permittivity have aroused widespread attention because of their distinctive properties and broad potential prospects. It is indicated that an enormously negative permittivity with a large value is not conducive to performance optimizing and impedance matching. In this article, the 2D Mxene Ti3 C2 Tx was selected as the conductive phase instead of metal and carbon materials to fabricate Ti3 C2 Tx /poly(vinylidene fluoride) metacomposites. The results of dielectric properties indicated that the conductive Ti3 C2 Tx networks were formed by Ti3 C2 Tx contacting with each other near the percolation threshold (ƒc ). The as‐obtained metacomposites containing 75 wt% Ti3 C2 Tx generated percolating phenomenon. Additionally, when the fraction of Ti3 C2 Tx was below ƒc, the frequency dispersion behaviors of conductivity were in accordance with the Jonscher's power law, which proved that conducting mechanism was dependent on hopping conduction. While above ƒc, the conductivity conformed to the Drude model and Lorentz model, which demonstrated a conductive behavior. Furthermore, the real part of permittivity transformed to negative value at 75 wt%, which can be explained as the existence of the low‐frequency plasma oscillation and electric‐dipole‐induced resonance. The dielectric loss of the metacomposite was also analyzed by the imaginary permittivity spectra. Small negative permittivity values in the range of −550 to −400 were observed, owing to the low free carrier concentration in composites. The appearance of weakly negative permittivity opened up a new direction in negative dielectric materials by 2D layered Ti3 C2 Tx nanomaterials.