Atomistic modeling toward the understanding of defect kinetics and degradation mechanism in solid systems

点击翻译按钮获取中文摘要

Long-term degradation processes in solid oxide fuel cell (SOFC) are mainly governed by the cation diffusion. However, the cation diffusion is a considerably slow process compared with the oxygen diffusion, such that a molecular dynamics is not generally suitable to predict the rate for the cation migration due to its limited time scale. In this work, we have investigated a vacancy-mediated cation diffusion in YSZ by utilizing metadynamics and Kinetic Monte Carlo method. Metadynamics simulations allow us to compute temperature-dependent activation free energy of cation migration in the typical experimental temperature range of SOFC. Beside, our Kinetic Monte Carlo simulations successfully provide a diffusion coefficient for Zr and Y in 8 mol% YSZ, which is in good agreement with an experimental result.