Ultraweakly and fine-tunable negative permittivity of polyaniline/nickel metacomposites with high-frequency diamagnetic response

Metacomposites have drawn considerable attention due to their enticing prospect in electronic and dielectric devices, which meanwhile unfortunately suffered from extremely high negative permittivity ( ε'  < 0). Herein, we put forward a strategy to suppress the plasma oscillation in metacomposites and thereby constrain the value of negative permittivity by introducing the semiconductive polyaniline to construct polyaniline/nickel (PANI/Ni) metacomposites. Weakly negative permittivity was obtained at a magnitude of 10 2 over the whole test frequency band, which is remarkably lower by at least three orders of magnitude than that of most metacomposites. The ε′ -negative value was resultantly fine-tuned by about 10 2 with equally adjusting Ni content. Lorentz and Drude models were employed to describe ε′ -negative spectra, indicating that both dielectric resonance and plasma oscillation contributed to negative permittivity. Negative susceptibility of ε′ -negative materials was mainly ascribed to high-frequency diamagnetic response within Ni networks. The well-designed PANI/Ni metacomposites with weakly and fine-tuning negative permittivity can greatly benefit the practical applications on electromagnetic (EM) shielding, microwave absorption and novel EM sensors.