Adjustable Graphene/Polyolefin Elastomer Epsilon-near-Zero Metamaterials at Radiofrequency Range.

While epsilon-near-zero (ENZ) metamaterials have marvelously shown various application prospects, the way to construct intrinsic ENZ metamaterials and adjust their ENZ properties precisely is still uncovered. The realization of stable and broadband ENZ properties at the radiofrequency range is of great significance. Herein graphene/polyolefin elastomer (POE) intrinsic ENZ metamaterials are initially constructed via the nanohybrid process. The metamaterials possess excellent adjustable ENZ properties by adjusting the content and reduction methods of graphene. The permittivities maintain between -1 and 1 steadily with increasing graphene content, which is attributed to the moderated carrier concentration of the conductive networks in the nanohybrids. Besides, different reduction methods also have significant impacts on ENZ properties. The hydrazine hydrate reduction method increases the maximum ENZ frequency region to 126 MHz. Lorentz type resonance is reasonable for the positive-negative transition in the ENZ frequency regions. As a significant indicator of the emergence of ENZ property, the sudden peak of dielectric loss tangent is observed. This work offers novel routes to construct intrinsic ENZ metamaterials with excellent adjustability in both values of permittivity and ENZ frequency regions.