Extreme temperature gradient promoting oxygen diffusion in yttria‐stabilized zirconia: A molecular dynamics study.

The oxidation resistance of yttria‐stabilized zirconia (YSZ) thermal barrier coatings and conductivity of YSZ solid oxide fuel cells are closely related to the diffusion of oxygen ions (O2−$\text{O}^{2-}$) in YSZ, but the O2−$\text{O}^{2-}$ diffusion behavior in small‐sized YSZ samples under non‐isothermal condition where the temperature gradient (∇T$\nabla T$) could be significant remaining elusive. Herein, we disclose the previously unrevealed effect of extreme ∇T$\nabla T$ on the self‐diffusion behavior of O2−$\text{O}^{2-}$ in both pristine and strained YSZ. It is found that the O2−$\text{O}^{2-}$ self‐diffusion coefficient (D$D$) experiences a nearly one‐fold increase under an extreme ∇T$\nabla T$ around 60 K/Å. The diffusion direction tends to be toward regions of high temperature. Uniaxial stress is revealed to reduce D$D$ due to the increased activation energy of ions, whereas ∇T$\nabla T$ promotes the O2−${\text{O}}^{2-}$ self‐diffusion in the stressed system. These results underscore the role of ∇T$\nabla T$ in influencing the self‐diffusion behavior of YSZ, providing a theoretical guideline for examining ceramics serving in extreme environments. [ABSTRACT FROM AUTHOR]