Modulating the negative permittivity of metacomposites by adjusting inductance and capacitance with the incorporation of Ag and Ag@SiO2

Metacomposites that have tunable negative permittivity show broad application potential in the domain of electromagnetics. In this study, the impregnation method was employed to successfully synthesize and impregnate silver (Ag) and silica-coated Ag (Ag@SiO₂) nanoparticles into a carbon cloth (CC) matrix. The content ratio of Ag and Ag@SiO₂ was regulated to adjust the negative permittivity of the composites. The results showed that a conductive network gradually formed in the composites and plasma oscillations occurred with the increase of Ag content, which thereby increased alternating current (AC) conductivity and the absolute values of negative permittivity. After Ag@SiO 2 nanoparticles were added, however, the conductive network was disrupted, which reduced electrical conductivity. Ag@SiO₂ regulated the frequency dispersion behavior of negative permittivity through Lorentz resonance. Thus, negative permittivity and frequency responses were successfully adjusted via the adjustment of the ratio between the inductive (Ag) and the capacitive (Ag@SiO₂) components in the composites. The findings offer a novel approach for designing lightweight metacomposites with precisely adjustable negative permittivity and frequency response characteristics.