Oxygen ion diffusivity in strained yttria stabilized zirconia: where is the fastest strain?

作者：Akihiro Kushima, Bilge Yildiz · 发表于：Journal of Materials Chemistry · 年份：2010 · DOI：10.1039/c000259c · 被引用次数：327 · 研究领域：Advancements in Solid Oxide Fuel Cells、Nuclear materials and radiation effects、Advanced Condensed Matter Physics

We present the mechanism and the extent of increase in the oxygen anion diffusivity in Y2O3 stabilized ZrO2 (YSZ) under biaxial lattice strain. The oxygen vacancy migration paths and barriers in YSZ as a function of lattice strain was assessed computationally using density functional theory (DFT) and nudged elastic band (NEB) method. Two competing and non-linear processes acting in parallel were identified to alter the migration barrier upon applied strain: (1) the change in the space, or electronic density, along the migration path, and (2) the change in the strength of the interatomic bonds between the migrating oxygen and the nearest neighbor cations that keep the oxygen from migrating. The increase of the migration space and the weakening of the local oxygen–cation bonds correspond to a decrease of the migration barrier, and vice versa. The contribution of the bond strength to the changes in the migration barrier is more significant than that of the opening of migration space in strained YSZ. A database of migration barrier energies as a function of lattice strain for a set of representative defect distributions in the vicinity of the migration path in YSZ was constructed. This database was used in kinetic Monte Carlo (KMC) simulations to estimate the effective oxygen diffusivity in strained YSZ. The oxygen diffusivity exhibits an exponential increase up to a critical value of tensile strain, or the fastest strain. This increase is more significant at the lower temperatur...