Maxwell Displacement Current and Nature of Jonsher's "Universal" Dynamic Response in Nanoionics

Abstract

New notion - Maxwell displacement current on potential barrier - is introduced in the structure-dynamic approach of nanoionics for description of collective phenomenon: coupled ion-transport and dielectric-polarization processes occurring during ionic space charge formation and relaxation in non-uniform potential relief. We simulate the processes: (i) in an electronic conductor/advanced superionic conductor (AdSIC) ideally polarizable coherent heterojunction, (ii) in a few strained monolayers of solid electrolyte (SE) located between two AdSICs forming coherent interfaces with SE. We prove the sum of ionic current over any barrier and Maxwell displacement current through the same barrier is equal to the current of current generator. "Universal" dynamic response, Re s*(w) ~ s^n (n < 1), was found for frequency-dependent conductivity s*(w) for case (ii) with an exponential distribution of potential barrier heights in SE. The nature of phenomenon is revealed. The amplitudes of non-equilibrium ion concentrations (and induced voltages) in space charge region of SE change approximately as ~ w^-1. Amplitudes yield a main linear contribution to Re s*(w). The deviation from linearity is provided by the cosine of phase shift fi between current and voltage in SE-space charge but cos fi depends relatively slightly on w (near constant loss effect) for coupled ion-transport and dielectric-polarization processes.