Structural Transitions in Superionic Conductors

Abstract

The $\ensuremath{\alpha}\ensuremath{\rightleftarrows}\ensuremath{\beta}$ phase transition in AgI is studied with use of the new molecular-dynamics technique which allows for a dynamical variation of the shape and size of the cell. In the present model, upon heating of $\ensuremath{\beta}$-AgI, the iodine ions undergo a hep \ensuremath{\rightarrow} bee transformation and silver ions become mobile, whereas the reverse transformation is observed on cooling of $\ensuremath{\alpha}$-AgI. The calculated $\ensuremath{\alpha}\ensuremath{\rightleftarrows}\ensuremath{\beta}$ transition temperature and structural and dynamical properties are in good agreement with experiments.