Insight into the grain boundary effect on the ionic transport of yttria-stabilized zirconia at elevated temperatures from a molecular modeling perspective

A molecular dynamics (MD) simulation is used to reveal the grain boundary effect on the ionic transport of yttria-stabilized zirconia (YSZ). The oxygen ion displacements and diffusivities of the ideal and grain boundary-inserted YSZ models are analyzed at elevated temperatures. An optimized Y2O3 concentration within YSZ for the best ionic conductivity is achieved by balancing the trade-off between the increased vacancies and the decreased accessible free space. The mass transfer resistance of the grain boundary in YSZ can be more easily found at higher temperatures by observing the oxygen ion diffusivities or traveling trajectories. At lower temperatures, the grain interior and the grain boundary control the ionic transport. In contrast, the grain boundary effect on the diffusion barrier is gradually eliminated at elevated temperatures. The modeled results in this work agree well with previous experimental data.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► GB in YSZ structure resulted in degraded ion transport and lower ion diffusivity. ► The GB effect can be more easily observed at higher temperatures. ► GB influence eliminated at higher T because migration energy barrier was overcome.