Oxide-ion conduction in the Dion-Jacobson phase CsBiTiNbO.

Oxide-ion conductors have found applications in various electrochemical devices, such as solid-oxide fuel cells, gas sensors, and separation membranes. Dion-Jacobson phases are known for their rich magnetic and electrical properties; however, there have been no reports on oxide-ion conduction in this family of materials. Here, for the first time to the best of our knowledge, we show the observation of fast oxygen anionic conducting behavior in CsBiTiNbO. The bulk ionic conductivity of this Dion-Jacobson phase is 8.9 × 10 S cm at 1073 K, a level that is higher than that of the conventional yttria-stabilized zirconia. The oxygen ion transport is attributable to the large anisotropic thermal motions of oxygen atoms, the presence of oxygen vacancies, and the formation of oxide-ion conducting layers in the crystal structure. The present finding of high oxide-ion conductivity in rare-earth-free CsBiTiNbO suggests the potential of Dion-Jacobson phases as a platform to identify superior oxide-ion conductors.