Fast-ion conduction and flexibility of glassy networks

TL;DR

This study investigates how the electrical conductivity of AgI-AgPO3 glasses changes with composition, revealing phase transitions that influence ion mobility and network flexibility, supported by experimental and theoretical analysis.

Contribution

It identifies two rigidity phase transitions in glassy electrolytes and links these to changes in ionic conductivity, combining experimental and theoretical insights.

Findings

Conductivity increases with AgI content, especially in the flexible phase.

Two thresholds at 9.5% and 37.8% AgI mark phase transitions.

Power-law increase in conductivity in the flexible phase.

Abstract

We observe two thresholds in the variations of electrical conductivity of dry solid electrolyte (AgI)x(AgPO3)1-x glasses, when the AgI additive concentration x increases to 9.5% and to 37.8%. Raman scattering complemented by calorimetric measurements confirm that these thresholds are signatures of the rigidity phase transitions; at x = 9.5% from a stressed rigid to an isostatically (stress free) rigid phase, and at x = 37.8% from isostatically rigid to a flexible phase. In the flexible phase, the electrical conductivity seems to increase as a power of x, this is in good agreement with the theoretical prediction based on 3d percolation.