Communication-Tunable Negative Permittivity of Cobalt and Epoxy Composites at 3 kHz ∼ 1 MHz Frequency Regions

Negative permittivity in percolation composites has drawn much attention owing to their potential application. This study set out to explore whether tunable negative permittivity can be realized in metal composites at 3 kHz similar to 1 MHz frequency regions. When the content of cobalt is 80 wt%, the permittivity turns to negative in the test band. These findings show that the Co conductive network has formed and provides large numbers of free electrons. Meanwhile, the percolation composites with negative permittivity show inductive characteristic. This research supports the idea that tunable low-frequency negative permittivity can be realized in metal composites.