Analyzing the strong influence of the cationic environment on the charge carrier’s jumping in a superionic conductor

Abstract

In this work the relationship between the structure of a solid ionic material and its ionic dynamics has been studied by impedance spectroscopy, differential scanning calorimetry and molecular dynamics simulation. Nanometric samples of AgI were synthesized to study the cation dynamics when it reaches its superionic behavior. The observed thermal events corresponded to the changes obtained on the dc conductivity behavior. This correspondence was microscopically explained by the ion dynamics revealed in the molecular dynamics simulation. The comprehensive analysis made it possible to confirm the weak short-range interactions between silver cations and iodide anions and exposed that the most mobile cation jumps are constrained by their neighbor cations. This finding explains the Kohlrausch–Williams–Watts β parameter value of 0.9 in the α phase where the AgI becomes a superionic conductor, an aspect that becomes essential to design a superionic conductor by doping ionic conductor materials.