Pasturel A, Jakse N
Univ. Grenoble Alpes, CNRS, Grenoble INP, SIMaP, F-38000, Grenoble, France.
Sci Rep. 2018 Sep 25;8(1):14314. doi: 10.1038/s41598-018-32594-w.
Bringing a liquid into contact with a solid is known to generally promote crystal nucleation at the freezing temperature. In contrast, it is much more difficult to conceive that a solid surface may hinder nucleation and favor large undercooling effects. Here we report on ab initio and classical molecular dynamic simulations to capture the underlying structural mechanism responsible for this striking effect. We find that the substrate/liquid interactions exert an important influence on in-plane ordering of the adjacent liquid layers in the undercooling regime. In particular, we identify that the presence of atomic arrangements with five-fold symmetry (FFS) on the substrate surface in the form of pentagonal atomic motifs allows the liquid to be undercooled well below its freezing temperature. Our findings clearly demonstrate that this pentagonal-coordinated surface enhances the presence of local arrangements with FFS in the adjacent liquid layers that prevents the crystal nucleation. Finally we suggest new technological developments to attain large undercooling effects.
使液体与固体接触通常会在凝固温度下促进晶核形成。相比之下，很难想象固体表面会阻碍成核并有利于大过冷效应。在此，我们报告了从头算和经典分子动力学模拟，以捕捉造成这种显著效应的潜在结构机制。我们发现，在过冷状态下，基底/液体相互作用对相邻液体层的面内有序性有重要影响。特别是，我们确定基底表面以五角形原子图案形式存在的具有五重对称性（FFS）的原子排列，使得液体能够被过冷到远低于其凝固温度。我们的研究结果清楚地表明，这种五重配位表面增强了相邻液体层中具有FFS的局部排列的存在，从而阻止了晶体成核。最后，我们提出了实现大过冷效应的新技术发展方向。
