Research

2014

J.A. Davis, D. Brown, W. Henderson, “Fractal Electrode Formation in Metal-Insulator Composites Near the Percolation Threshold,’ IEEE Transactions on Nanotechnology, vol. 12, no. 5, pp. 725-733, September 2013.

J.A. Davis, D. Brown, W. Henderson, “Fractal Electrode Formation in Metal-Insulator Composites Near the Percolation Threshold,’ IEEE Transactions on Nanotechnology, vol. 12, no. 5, pp. 725-733, September 2013.

Electrical Properties of Nanocomposite Materials

Developing new materials and devices that have extremely long life cycles and deliver high bursts of energy would help to advance a variety of applications that range from mobile storage systems (e.g. for mobile computing or electric vehicles) to pulsed power technologies (e.g. for railguns or laser systems) to larger storage facilities for alternative energy generation (e.g. for wind or solar power stations).  This research effort combines both nanofabrication and numerical simulation to study the polarizability and electric field strength of material interfaces in unique composite configurations.  This investigation is predicated on a variety of observations over the past 20 years during which numerous experiments have revealed a large increase in the low-frequency capacitance of devices constructed from metal-insulator or multi-insulator composite materials.  These capacitive increases are typically reported as dramatic increases in the effective relative dielectric constants of the nanocomposite material.  A class of these metal-insulator composites that have metal particle concentrations near the percolation threshold have been shown to have a dramatic increase in the effective dielectric constant ranging from 3-8 orders of magnitude.   Multi-insulator (e.g. SiO2, Si3N4, Al2O3, and TiO2) nanocomposites have also been shown to increase the permittivity at low frequencies from 1-2 orders of magnitude. To date, there are many competing theories to explain the phenomenon behind these anomalous increases in low frequency dielectric behavior, which range from the Gor’kov-Eliashberg effect to the Maxwell-Wagner effect to percolation theory of metal-insulator transitions.

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