Tailorable epsilon-negative and epsilon-near-zero behavior of TiC/CCTO metacomposites: Low-frequency plasma oscillation

Epsilon-negative ( ? ′ $?\prime$ < 0) and epsilon-near-zero (ENZ) property was demonstrated in titanium carbide/copper calcium titanate (TiC/CCTO) metacomposites. Benefiting from the moderate concentration of free electrons in TiC filler and its adjustable three-dimensional (3D) networks, weakly negative permittivity ( ∼ − $\sim -$ 200 at 20 MHz) was achieved. Not only that, tailoring the negative permittivity of metacomposites from ∼ − $\sim -$ 200 to ∼ − $\sim -$ 2060, ∼ − $\sim -$ 4200, ∼ − $\sim -$ 14000 and ∼ − $\sim -$ 70000 at 20 MHz was realized by simply increasing TiC content. Besides, Drude model was used to explain the radio-frequency (RF) negative permittivity and quantified the collective plasma oscillation in TiC networks.