Department of Materials Science and Engineering, University of California, Davis, Davis, CA 95616, USA.
Department of Chemical Engineering, University of California, Davis, Davis, CA 95616, USA.
Phys Chem Chem Phys. 2018 May 16;20(19):13215-13223. doi: 10.1039/c8cp02010h.
The effect of La3+ doping on the structure and ionic conductivity change in nanocrystalline yttria-stabilized zirconia (YSZ) was studied using a combination of Monte Carlo and molecular dynamics simulations. The simulation revealed the segregation of La3+ at eight tilt grain boundary (GB) structures and predicted an average grain boundary (GB) energy decrease of 0.25 J m-2, which is close to the experimental values reported in the literature. Cation stabilization was found to be the main reason for the GB energy decrease, and energy fluctuations near the grain boundary are smoothed out with La3+ segregation. Both dynamic and energetic analysis on the Σ13(510)/[001] GB structure revealed La3+ doping hinders O2- diffusion in the GB region, where the diffusion coefficient monotonically decreases with increasing La3+ doping concentration. The effect was attributed to the increase in the site-dependent migration barriers for O2- hopping caused by segregated La3+, which also leads to anisotropic diffusion at the GB.
采用蒙特卡罗和分子动力学模拟相结合的方法研究了 La3+掺杂对纳米晶氧化钇稳定氧化锆（YSZ）结构和离子电导率变化的影响。模拟揭示了 La3+在 8 种倾斜晶界（GB）结构中的偏析，并预测平均 GB 能降低 0.25 J m-2，这与文献中报道的实验值接近。发现阳离子稳定化是 GB 能降低的主要原因，La3+的偏析使晶界附近的能量波动趋于平稳。对Σ13(510)/[001]GB 结构的动力学和能量分析表明，La3+掺杂阻碍了 GB 区域中 O2-的扩散，其中扩散系数随 La3+掺杂浓度的增加呈单调下降趋势。这种影响归因于 La3+偏析导致 O2-跳跃的位相关迁移势垒增加，这也导致了 GB 处的各向异性扩散。
