Induced polarization: Simulation and inversion of nonlinear mineral electrodics |
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Authors: | Olu Agunloye |
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Institution: | (1) Geotechnical Research Laboratory, Brink Jones & Co. Ltd., U.I. P.O. Box 9390, Ibadan, Nigeria |
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Abstract: | Graph-theoretic representations are used to model nonlinear electrodics, while forward and inverse simulations are based on
reaction rate theory. The electrodic responses are presented as distorted elliptical Lissajous shapes obtained from dynamic
impedance over a full cycle. Simulations show that asymmetry in reaction energy barrier causes slight asymmetry in the shape
of the response ellipse and hardly affects the phase angle of the complex electrode impedance. The charge transfer resistance
and the diffusion constraints tend to have opposite effects. The former causes reduction in the phase angle, tending to make
the impedance purely resistive. Both of these mechanisms show saturation effects. Charge transfer resistance at its limit
forces a thin S-type symmetry on the Lissajous patterns, while with diffusion control the size of the Lissajous patterns begins
to reduce after saturation. The fixed layer causes substantial increase in the phase angle and tends to “enlarge” the Lissajous
patterns. It is responsible for the hysteresis-like shapes of the Lissajous patterns when superimposed on strong charge transfer
resistance. This study shows that it is quite possible to deduce the mechanisms that control the electrodic processes by inverting
electrodic parameters from “observed” distorted, nonelliptical Lissajous patterns characteristic of nonlinear electrodics.
The results and qualities of the inversion technique are discussed. |
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Keywords: | Nonlinear electrodics Inversion Mineral descrimination |
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