Nonlinear Ionic Conductivity of Thin Solid Electrolyte Samples: Comparison between Theory and Experiment

TL;DR

This paper investigates nonlinear ionic conductivity in thin disordered electrolytes through combined experimental measurements and theoretical modeling, revealing size-dependent effects and challenging the interpretation of apparent hopping distances.

Contribution

It provides a comprehensive comparison between experimental data and theoretical models, highlighting the limitations of current interpretations of nonlinear conductivity in disordered ionic conductors.

Findings

Apparent hopping distances up to 43 Å were measured experimentally.

Nonlinearity scales with system size in the 1D theoretical model.

Nonlinear conductivity cannot generally be interpreted solely by apparent hopping distances.

Abstract

Nonlinear conductivity effects are studied experimentally and theoretically for thin samples of disordered ionic conductors. Following previous work in this field the {\it experimental nonlinear conductivity} of sodium ion conducting glasses is analyzed in terms of apparent hopping distances. Values up to 43 \AA are obtained. Due to higher-order harmonic current density detection, any undesired effects arising from Joule heating can be excluded. Additionally, the influence of temperature and sample thickness on the nonlinearity is explored. From the {\it theoretical side} the nonlinear conductivity in a disordered hopping model is analyzed numerically. For the 1D case the nonlinearity can be even handled analytically. Surprisingly, for this model the apparent hopping distance scales with the system size. This result shows that in general the nonlinear conductivity cannot be interpreted in terms of apparent hopping distances. Possible extensions of the model are discussed.