A combined molecular dynamics simulation, experimental and coupling model study of the ion dynamics in glassy ionic conductors

Dielectric relaxation measurements of the ion dynamics in glassy, molten and crystalline ionic conductors show general properties independent of chemical composition and structure. These include the appearance of a near-constant loss at high frequencies/low temperatures and the transition to a many-particle ion-hopping regime at lower frequencies. We use a combination of molecular dynamics simulation, experimental data analysis and the coupling model to characterize the ion dynamics in the near-constant-loss regime, the transition zone, and the many-particle ion-hopping regime. An improved understanding is gained of the origin of the near-constant loss and the evolution of the ion dynamics, from short times when the ions are caged, to long times when they are no longer caged but participate in the many-particle dynamics, giving rise finally to dc conductivity. Reasons are given to refute criticism of use of the electric modulus to represent and interpret experimental data.