Hopping Transport in the Presence of Site Energy Disorder: Temperature and Concentration Scaling of Conductivity Spectra

TL;DR

This paper uses Monte Carlo simulations to explore how site energy disorder affects ionic conductivity spectra, revealing conditions under which experimental scaling behaviors can be reproduced.

Contribution

The study demonstrates that a lattice model with site energy disorder can explain the temperature and concentration scaling of conductivity spectra observed in experiments.

Findings

At low temperatures and typical concentrations, the model reproduces experimental scaling.

The model accounts for changes in ionic activation energies with concentration.

Conductivity spectra generally do not scale, except under specific conditions.

Abstract

Recent measurements on ion conducting glasses have revealed that conductivity spectra for various temperatures and ionic concentrations can be superimposed onto a common master curve by an appropriate rescaling of the conductivity and frequency. In order to understand the origin of the observed scaling behavior, we investigate by Monte Carlo simulations the diffusion of particles in a lattice with site energy disorder for a wide range of both temperatures and concentrations. While the model can account for the changes in ionic activation energies upon changing the concentration, it in general yields conductivity spectra that exhibit no scaling behavior. However, for typical concentrations and sufficiently low temperatures, a fairly good data collapse is obtained analogous to that found in experiment.