Abstract Diffusion of impurities along grain boundaries of compound materials is of high relevance for multiple practical applications. In this work, we perform a case study of Cu-impurity diffusion along the special coincident site lattice model Σ 5 (012)[100] GB in stoichiometric and off-stoichiometric TiN. The study includes a thorough investigation of the GB structure, formation of point defects and their interaction with a Cu-impurity at the interface as well as the evaluation of energy barriers for a few plausible impurity migration pathways along TiN grain boundaries. The results show that one of the most probable diffusion mechanisms (with an activation energy of 0.77 eV) is Cu-interstitial migration along a grain boundary channel. For a non-stoichiometric case when nitrogen vacancies can be present at GB, the results show that they can act as trapping centers for Cu atoms and increase the migration energy barrier to 1.2 eV. However, our results also indicate that at equilibrium conditions the effect of trapping may be reduced due to slightly unfavored segregation of N vacancies at TiN grain boundaries.

中文翻译：

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TiN 中 Σ 5 (012)[100] 晶界处的点缺陷和 Cu 扩散的早期阶段：从头算研究

摘要 杂质沿复合材料晶界的扩散与多种实际应用密切相关。在这项工作中，我们在化学计量和非化学计量的 TiN 中沿着特殊的重合位点晶格模型 Σ 5 (012)[100] GB 进行了 Cu 杂质扩散的案例研究。该研究包括对 GB 结构、点缺陷的形成及其与界面处 Cu 杂质的相互作用的彻底调查，以及对沿 TiN 晶界的一些可能的杂质迁移途径的能量势垒的评估。结果表明，最可能的扩散机制之一（活化能为 0.77 eV）是沿晶界通道的 Cu 间隙迁移。对于非化学计量的情况，当 GB 处可能存在氮空位时，结果表明，它们可以作为 Cu 原子的俘获中心，并将迁移能垒提高到 1.2 eV。然而，我们的结果还表明，在平衡条件下，由于 TiN 晶界处 N 空位的偏析略微不利，捕获的影响可能会降低。