Revisiting the percolation phenomena in dielectric composites with conducting fillers

摘要

The composition (φ) dependence of the effective dielectric constant (εeff) on conductor-dielectric composites is widely described as εeff∝(φc−φ)−s. This relationship has been extensively used to fit experimental results for determining the percolation behavior (percolation threshold φc and power constant s). The equation was checked using experimental results from two 0–3 nanocomposite systems with uniform microstructures. It is found that the equation can be used to fit the experimental results, but the fitting constants (φc and s) do not reflect the percolation behavior: the values of both fitting constants are dependent on the frequency (f) and temperature selected. It is also found that the fitting constant φc increases with increasing frequency selected and it is believed that this arises from the critical phenomenon, εeff∝fγ−1, for composites close to the φc.