Tunable and weakly negative permittivity at radio frequency range based on titanium nitride/polyethylene terephthalate composites

Metacomposites have been induced widespread concern in the realization of negative permittivity. In this paper, composites with titanium nitride (TiN) particles homogeneously dispersed in polyethylene terephthalate (PET) resin were prepared by high energy ball-milling and adhesive hot-pressing method. The influences of TiN networks in composites on the electric and dielectric properties were investigated in detail. With the formation of conductive TiN networks, the conductance mechanism changed from hopping conduction to metal-like conduction. The tunable and weakly negative permittivity in the radio frequency range was obtained in TiN/PET composites by adjusting the frequency range and volume fraction ( v ) of TiN in composites. Negative permittivity behavior raises from the low-frequency plasma oscillation of free electrons in TiN networks, which could be analyzed by the Drude model. The impedance of TiN/PET composites were investigated by the equivalent circuit analysis, demonstrating the capacitive or inductive of the composites. This paper shows an effective way toward the tunable and weakly negative permittivity, which will promote practical applications of metacomposites in electromagnetic shielding and impedance matching fields.