Recent advances in radio-frequency negative dielectric metamaterials by designing heterogeneous composites

Dielectric constant (epsilon, epsilon) is one of the basic physical parameters for materials, determining the response of materials to electromagnetic waves or electrical field; its value is generally positive. In fact, dielectric constant can also be negative, regarded as supernormal performance to some degree. The negative dielectric property has become research hotspot as an essential key for constructing metamaterials, showing unique and exotic electromagnetic properties not existing in naturally occurring materials, such as negative refraction, perfect troubles, and reverse Doppler effect. Recently, the feasibility is demonstrated to achieve negative dielectric property in conventional heterogeneous composites rather than periodic artificial arrays; drawing great attention from researchers in material science and engineering, many advances have been made and can promote the development of metamaterials and conventional electromagnetic functional materials. Here, we reviewed the recent advances in negative dielectric property designed in some heterogeneous composites, including metal composites, carbon composites, ceramic composites, conducting polymer. Besides, various strategies, including designing different microstructures, changing the working temperatures, choosing flexible matrix or fillers, electro-magnetic coupling, were summarized to precisely adjust negative dielectric property. Finally, the question unsolved and perspectives about negative dielectric property are put forward; we expect to shed light on the mechanism of negative dielectric property as well as its relationship with the material design in composition and microstructure.

Automated summary

Dielectric constant is a physical parameter that determines the response of materials to electromagnetic waves or electrical field. Negative dielectric property, a key for constructing metamaterials, has unique electromagnetic properties. Recent advances have demonstrated the feasibility of achieving negative dielectric property in heterogeneous composites.