Tunneling-percolation origin of nonuniversality: Theory and experiments
- 16 February 2005
- journal article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 71 (6)
- https://doi.org/10.1103/physrevb.71.064201
Abstract
A vast class of disordered conducting-insulating compounds close to the percolation threshold is characterized by nonuniversal values of transport critical exponent t, in disagreement with the standard theory of percolation which predicts t = 2.0 for all three dimensional systems. Various models have been proposed in order to explain the origin of such universality breakdown. Among them, the tunneling-percolation model calls into play tunneling processes between conducting particles which, under some general circumstances, could lead to transport exponents dependent of the mean tunneling distance a. The validity of such theory could be tested by changing the parameter a by means of an applied mechanical strain. We have applied this idea to universal and nonuniversal RuO2-glass composites. We show that when t > 2 the measured piezoresistive response \Gamma, i. e., the relative change of resistivity under applied strain, diverges logarithmically at the percolation threshold, while for t = 2, \Gamma does not show an appreciable dependence upon the RuO2 volume fraction. These results are consistent with a mean tunneling dependence of the nonuniversal transport exponent as predicted by the tunneling-percolation model. The experimental results are compared with analytical and numerical calculations on a random-resistor network model of tunneling-percolation.Comment: 13 pages, 12 figureKeywords
This publication has 68 references indexed in Scilit:
- Precise determination of the conductivity exponent of 3D percolation using exact numerical renormalizationZeitschrift für Physik B Condensed Matter, 2000
- Effect of strain on the properties of an ethylene-octene elastomer with conductive carbon fillersJournal of Applied Polymer Science, 2000
- Effect of the mold temperature on the electrical properties of carbon-black-loaded polystyrene/SB block copolymer blendsJournal of Applied Polymer Science, 1998
- Percolation Threshold of Carbon Black-Polyethylene CompositesJapanese Journal of Applied Physics, 1997
- Temperature and magnetic-field dependence of the resistivity of carbon-black polymer compositesPhysical Review B, 1997
- PRECISE DETERMINATION OF THE CONDUCTIVITY EXPONENT OF 3D PERCOLATION USING "PERCOLA"International Journal of Modern Physics C, 1996
- Composites based on micron-sized exfoliated graphite particles: Electrical conduction, critical exponents and anisotropyJournal of Physics and Chemistry of Solids, 1996
- Current distribution in the three-dimensional random resistor network at the percolation thresholdPhysical Review E, 1996
- Temperature-dependent resistivity and conduction mechanism in carbon particle-filled polymersJournal of Materials Science, 1992
- Piezoresistivity of heterogeneous solidsJournal of Applied Physics, 1987