Imaging of conductive filler networks in heterogeneous materials by scanning Kelvin microscopy

This article reports a novel application of scanning Kelvin microscopy for exclusively revealing the distribution of a percolated conductive filler ne twork in heterogeneous materials. The materials under investigation are car bon black and carbon nanotube-filled epoxies with a highly inhomogeneous co nductivity distribution due to their fabrication. The Kelvin method is demo nstrated to be especially suitable for resolving the resistive particle net work in these kinds of composite materials with sample resistance levels in the megaohm range. Transmission optical microscopy reveals matches between the scanning Kelvin images and the sample morphologies, whereas the percol ating backbone cannot be distinguished in the optical micrographs. (C) 2001 John Wiley & Sons, Inc.