Stimulated percolation of electrical conductivity in heterogenous mixtures

In a composite of liquid dielectric with granular conducting dopant in a form of a micrometre particles of conductor, one observes the structure ordering process due to external electric field, manifested by the increase of observed electrical conductivity. The mechanism of such an ordering is similar to the phenomena occurring in the electrorheological liquids. By application of the conductor particles as an active polar dopant, the observed ordering effects take place at lower values of the electric field, compared with the ordering case of the granular dopants of an insulator. A simple theoretical description of the above mentioned phenomena was developed. They are attributed to the mutual interaction of conducting particles, having the field-induced dipole moments. The measured current increase is due to the power dissipation in the sample, related to the particle motion in viscous medium, as well as to the increase of sample capacitance. The ordering effect of such a medium consists in the mutual electrostatic interaction of the electric dipoles, induced in the dopant particles, as well as in the buildup of a linear or dendritic spatial structures with a symmetry determined by the direction of the external electric field. In the theoretical part of the work, the assumption on the coagulation of conductor particles into linear conducting structures has been used. One can search, however, the theoretical argumentation based on Flory's concept with respect to the described dipole interactions and construct the statistical sum. By the application of the mathematical method, one can discuss topology and percolation effects in such mixtures. Apart from the effects of linear, regular ordering of the composite, one can observe also the nonlinear effects, when the conducting fractal structure is being created.