Zhang Xianxian, Tang Jianfeng, Zhang Xingming, Wang Liang, Yuan Dingwang, Deng Huiqiu, Deng Lei
School of Chemistry and Material Science, Hunan Agricultural University, Changsha 410128, China.
The Peac Institute of Multiscale Sciences, Chengdu 610207, China.
Phys Chem Chem Phys. 2024 Jun 19;26(24):17274-17281. doi: 10.1039/d4cp00633j.
Grain boundary (GB) segregation plays a pivotal role in maintaining and optimizing the remarkable catalytic or mechanical properties of nanocrystalline Pt by reducing the Gibbs free energy and thereby impeding structure degradation. The solute segregation behavior at the Pt GB, however, is not well understood at the atomic level. In this study, we employed first-principles calculations to elucidate the preferential segregation behavior of a single Au atom at the symmetrical tilt GB of Pt. For pure Pt, a linear relationship between the GB energy and excess volume is observed. Therefore, Au exhibits strong segregation tendencies towards GB to release excess energy and volume stored at the strained GB. Although the segregation energy is sensitive to various GB sites, it is interesting to note that the minimum one increases linearly with GB energy. This site-sensitivity of segregation energy can be attributed to mechanical, chemical, and interaction parts, which are quantitatively related to the atomic volume, coordination number, and average bond length, respectively. Finally, the interplay among different structural descriptors is revealed. These insights into the association between GB structures, segregation configuration and energy offers valuable atomic-scale quantitative insights into the segregation behavior of Au in Pt GBs, which holds significant implications for the design of Pt nanomaterials with enhanced thermal stability GB engineering.
晶界（GB）偏析通过降低吉布斯自由能从而阻碍结构降解，在维持和优化纳米晶铂卓越的催化或机械性能方面起着关键作用。然而，铂晶界处的溶质偏析行为在原子层面上尚未得到很好的理解。在本研究中，我们采用第一性原理计算来阐明单个金原子在铂对称倾斜晶界处的优先偏析行为。对于纯铂，观察到晶界能量与过量体积之间存在线性关系。因此，金表现出向晶界强烈的偏析倾向，以释放存储在应变晶界处的过量能量和体积。尽管偏析能对各种晶界位置敏感，但有趣的是，最小偏析能随晶界能量呈线性增加。偏析能的这种位置敏感性可归因于机械、化学和相互作用部分，它们分别与原子体积、配位数和平均键长定量相关。最后，揭示了不同结构描述符之间的相互作用。这些对晶界结构、偏析构型和能量之间关联的见解，为金在铂晶界中的偏析行为提供了有价值的原子尺度定量见解，这对设计具有增强热稳定性的铂纳米材料——晶界工程具有重要意义。
