SINTEF Industry, Sustainable Energy Technology, P.O. Box 124 Blindern, NO-0314 Oslo, Norway.
Phys Chem Chem Phys. 2018 Jul 18;20(28):19142-19150. doi: 10.1039/c8cp02443j.
The prospect of significantly enhanced oxide ion diffusion along grain boundaries in Sr-doped LaMnO3 (LSM) was investigated by means of density functional theory calculations applied to a Σ5 (3 1 0)[0 0 1] grain boundary. The structure of the grain boundary was optimized by rigid body translation, and segregation energies were calculated for oxygen vacancies and Sr-acceptors. Two potentially fast diffusion paths were identified along the grain boundary core based on the interconnectivity between neighbouring sites with a strong tendency for segregation of oxygen vacancies. The migration barriers for these paths, obtained with the nudged elastic band method, amounted to about 0.6 eV. Based on the obtained migration barriers and concentrations of oxygen vacancies for the relevant core sites, the grain boundary diffusion coefficient was estimated to be enhanced by 3 to 5 orders of magnitude relative to the bulk in the temperature range 500-900 °C. Space-charge effects were determined to be quite insignificant for the transport properties of LSM grain boundaries.
采用密度泛函理论计算研究了 Sr 掺杂 LaMnO3（LSM）中晶界上氧离子扩散显著增强的前景。对 Σ5（310）[001]晶界进行了结构优化，并计算了氧空位和 Sr 受体的偏析能。基于相邻位点之间强烈的氧空位偏析趋势的连通性，在晶界核中确定了两条潜在的快速扩散路径。利用势垒弹性带法得到的这些路径的迁移势垒约为 0.6 eV。基于获得的迁移势垒和相关核心位点的氧空位浓度，估计在 500-900°C 的温度范围内，晶界扩散系数相对于体相增强了 3 到 5 个数量级。对于 LSM 晶界的输运性质，空间电荷效应被确定为相当不重要。
