(544f) A More Efficient Model for the Emergent Ionic Conduction in Aliovalently Doped Zirconia

Fast ion conductors are used in solid state devices like fuel cells, electrolyzers and batteries. Despite their growing importance, a connection between microscopic hopping parameters and macroscopic ionic conduction, which is essential for materials design, is often not available. This is particularly true for aliovalently-doped oxide materials. Using yttria stabilized zirconia (YSZ) as a prototypical system, we demonstrate the complexity arising from anisotropic oxygen ordering when ions migrate in response to an electric field. Statistical analysis of classical molecular dynamics trajectories provides atomistically-resolved quantities as a function of the field strength and various local cation arrangements that make up the YSZ structure. The effect of anion ordering on individual oxygen ion hopping rates is determined. Contrary to standard rate theories, the hopping rate constant is found to be decrease with the field strength both in the direction of the applied field and against it. Despite this, the current density that emerges at the macroscopic scales considering contributions from different cation arrangements is consistent with Ohm’s law and other experimental observations. These insights suggest that it might be possible to build reduced complexity ionic conduction model for solid-state fast ion conductors.