Heterogeneous crystallization of hard and soft spheres near flat and curved walls
Heterogeneous crystallization of hard and soft spheres near flat and curved walls
复制标题
DOI：
10.1140/epjst/e2014-02101-7
复制
发表时间：
2014-02
期刊：
影响因子：
--
通讯作者：
K. Sandomirski;S. Walta;S. Walta;Janine Dubbert;E. Allahyarov;E. Allahyarov;Andrew B. Schofield;
中科院分区：
文献类型：
--
作者：
K. Sandomirski;S. Walta;S. Walta;Janine Dubbert;E. Allahyarov;E. Allahyarov;Andrew B. Schofield;
结晶是统计物理学中一个长期存在的问题，对许多实际和工业应用具有重要意义。它通常发生在容器壁或杂质存在的情况下，这通常是不可避免的，或者甚至可能是通过利用非均相成核来促进结晶的理想条件。异质成核依赖于种子。在这里，我们讨论种子的作用，并集中在一个非常普遍的情况下，即在存在平坦或弯曲的硬壁的情况下，硬和软胶体球的结晶。曲率作为一种简单的手段，在种子诱导的晶格和热力学有利的晶格之间引入可调的不匹配。这种不匹配会引起变形和弹性应力，而这些变形和弹性应力会随着晶体的生长而积累。这有一个重要的结果：一旦晶体达到临界尺寸，它就会从种子上分离出来，使种子松弛下来。松弛的晶体继续生长，但结晶在到达种子之前就停止了，种子现在代表一种杂质。因此，虽然种子有利于成核，但任何不匹配，如种子曲率或不相称的结构，都会引起不利的扭曲，并可能导致晶体的脱离。对于软球，可以利用其相互作用潜力和可能的变形来放松变形的附加机制。利用共聚焦显微镜研究了不同的多步骤过程，并将其与计算机模拟和理论结果进行了比较。
Crystallization represents a long-standing problem in statistical physics and is of great relevance for many practical and industrial applications. It often occurs in the presence of container walls or impurities, which are usually unavoidable or might even be desirable to facilitate crystallization by exploiting heterogeneous nucleation. Heterogeneous nucleation relies on a seed. Here we discuss the role of the seed and concentrate on a very generic situation, namely crystallization of hard and soft colloidal spheres in the presence of flat or curved hard walls. Curvature serves as a simple means to introduce a tunable mismatch between the seed-induced crystal lattice and the thermodynamically-favoured lattice. The mismatch induces distortions and elastic stress, which accumulate while the crystallite grows. This has an important consequence: once the crystallite reaches a critical size, it detaches from the seed allowing it to relax. The relaxed crystal continues to grow in the bulk, but crystallization ceases before reaching the seed, which now represents an impurity. Therefore, while seeds favour nucleation, any mismatch, like the seed curvature or an incommensurate structure, induces unfavourable distortions and can lead to the detachment of the crystallite. An additional mechanism to relax distortions is available to soft spheres, which can exploit their interaction potential and possibly deform. The different multi-step processes have been investigated by confocal microscopy, which provides particle-level information, and compared to computer simulations and theoretical results.