Origin of non-exponential relaxation in a crystalline ionic conductor: a multi-dimensional 109Ag NMR study

TL;DR

This study uses multi-dimensional 109Ag NMR to determine that non-exponential relaxation in a crystalline ionic conductor arises from dynamic heterogeneities, not intrinsic non-exponentiality or correlated jumps.

Contribution

It provides direct NMR evidence that non-exponential relaxation is due to rate distributions, clarifying the microscopic origin in crystalline silver conductors.

Findings

Non-exponential relaxation caused by rate distribution

No evidence for correlated back-and-forth jumps

Dynamic heterogeneities dominate relaxation behavior

Abstract

The origin of the non-exponential relaxation of silver ions in the crystalline ion conductor Ag7P3S11 is analyzed by comparing appropriate two-time and three-time 109Ag NMR correlation functions. The non-exponentiality is due to a rate distribution, i.e., dynamic heterogeneities, rather than to an intrinsic non-exponentiality. Thus, the data give no evidence for the relevance of correlated back-and-forth jumps on the timescale of the silver relaxation.