Fundamental questions relating to ion conduction in disordered solids

TL;DR

This paper discusses fundamental scientific questions about ion conduction in disordered solids, highlighting unresolved issues and proposing some answers, emphasizing the need for further research in this field.

Contribution

It reviews key questions in ion conduction in disordered solids and draws attention to fundamental challenges that remain unresolved.

Findings

Insights into ion transport mechanisms

Discussion on the origins of mixed-alkali effect

Identification of key challenges in the field

Abstract

A number of basic scientific questions relating to ion conduction in homogeneously disordered solids are discussed. The questions deal with how to define the mobile ion density, what can be learned from electrode effects, what is the ion transport mechanism, the role of dimensionality, and what are the origins of the mixed-alkali effect, of time-temperature superposition, and of the nearly-constant loss. Answers are suggested to some of these questions, but the main purpose of the paper is to draw attention to the fact that this field of research still presents several fundamental challenges.