Weakly negative permittivity from poly(butylene adipate-co-terephthalate)/FeCoNi@carbon metacomposites at the radio frequency band

Metacomposites with negative permittivity have received widespread attention in recent years due to their unique physical properties and their great application potential in fields such as electromagnetic shielding and wireless transmission. In this work, weakly negative permittivity properties at the radio frequency band are achieved by designing poly(butylene adipate-co-terephthalate)/FeCoNi@carbon composites. The alternating current conductivity, complex permittivity and impedance properties of the composites are studied. When the content of FeCoNi@carbon increases from 15 wt% to 20 wt%, the conductivity increases sharply, manifesting as percolation phenomenon. Additionally, the composites achieve a transition from positive permittivity to weakly negative permittivity with FeCoNi@carbon content increasing from 15 wt% to 20 wt% due to the formation of a percolating conductive network. The equivalent circuit model based on impedance data is also studied. The inductance appears in the equivalent circuit model, indicating that the conductive network is formed.