Impedance spectroscopy and equivalent circuits of metal-dielectric composites around the percolation threshold

Abstract

Although tunable metal/dielectric nanoparticle composites are promising candidates for a large number of potential applications in electronics, sensor technology, and optical devices, little has been done on their high frequency behavior. Here, we demonstrate that the high frequency response in the kHz to MHz range of Ag-nanoparticles embedded in the highly flexible elastomer PDMS can, on the one hand, be tuned by strain and, on the other hand, be nicely described by common equivalent circuits. Switching on and off the different elements of the equivalent circuit, namely, resistors, constant phase elements, and inductance, the impedance spectra of the composites can be modelled even across the percolation, encompassing both the insulating phase and the metallic state.