Computational Insights into Dion-Jacobson Type Oxide Ion Conductors.

Dion-Jacobson type materials have recently emerged as a new structural family of oxide ion conductors, materials important for applications in a variety of electrochemical devices. While some attempts to improve their ionic conductivity have been reported, a detailed understanding of the underlying oxide ion diffusion mechanisms in these materials is still missing. To explore the structure-property relationships leading to the favorable properties, we carried out ab initio molecular dynamics simulations of oxide ion diffusion in CsBi 2 Ti 2 NbO 10-δ . Our computational study reveals significant out-of-plane dynamics, indicating that the dominant pathway for oxide ion migration is via jumps into and out of the ( ab ) crystallographic plane. This suggests that further improvement of oxide ion conductivity relative to CsBi 2 Ti 2 NbO 10-δ could be achieved by enhancing the rotational flexibility of the coordination polyhedra located in the inner perovskite layer, thereby facilitating faster out-of-plane motions.