Universal paradigm of ternary metacomposites with tunable epsilon-negative and epsilon-near-zero response for perfect electromagnetic shielding

CaCu₃Ti₄O₁₂ (CCTO) ceramic nanocomposites incorporating graphene–carbon black (GRCB) fillers were fabricated by spark plasma sintering process. The percolative effects of conductive GRCB fillers on dielectric response of GRCB/CCTO ternary metacomposites were systematically investigated. The weakly real permittivity (ε′)-negative response (ε′ ~ − 1 × 10²) was achieved which originated from weakly low-frequency plasmonic state of free carriers within constructed GRCB networks. With enhancing three-dimensional GRCB network, the plasma frequency of metacomposites increased while the damping factor decreased. Herein, the ε′-negative values of metacomposites were tuned from − 10² to − 10⁴ orders of magnitude and ε′-near-zero (ENZ) frequencies from ~ 142 to ~ 340 MHz which substantially benefited from the moderate carrier concentration of GRCB dual fillers. The Drude model and equivalent circuit models were adopted to demonstrate dielectric and electrical characteristics. The obtained metacomposites show strong EM shielding effect along with enhanced plasmonic oscillation and even better achieving perfect EM shielding effect in ENZ media. This work achieves the tunable ε′-negative and ε′-near-zero response and more importantly clarifies its regulation mechanism in ceramic-based ternary metacomposites, which opens up the possibility of designing high-performance EM shielding materials based on metacomposites.