Visualizing kinetic pathways of homogeneous nucleation in colloidal crystallization
Visualizing kinetic pathways of homogeneous nucleation in colloidal crystallization
复制标题
胶体结晶中均匀成核的动力学路径可视化
DOI：
10.1038/nphys2817
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发表时间：
2014-01-01
期刊：
影响因子：
19.6
通讯作者：
Xu, Lei
中科院分区：
文献类型：
--
作者：
Tan, Peng;Xu, Ning;Xu, Lei
当系统经历从液相到固相的转变时，它在达到最终状态之前通过多个中间结构。然而，我们对这一过程的确切途径的了解是有限的，主要是由于难以实现直接观察。在这里，我们实验研究的对称性和密度的各种胶体系统在液体到固体的相变过程中的演变，并可视化动力学途径与单粒子分辨率。我们观察到形成相对有序的前体结构与不同的对称性，然后转化为亚稳态固体。在这个转换过程中，两个主要的交叉对称路径总是发生，无论最终状态和相互作用势。此外，我们发现了一个广泛的解耦的密度变化和对称性的发展，并发现，成核很少从致密区域开始。这些发现适用于我们所有的样品，这表明有可能找到一个统一的图片在胶体系统中的复杂的结晶动力学。
When a system undergoes a transition from a liquid to a solid phase, it passes through multiple intermediate structures before reaching the final state. However, our knowledge on the exact pathways of this process is limited, mainly owing to the difficulty of realizing direct observations. Here, we experimentally study the evolution of symmetry and density for various colloidal systems during liquid-to-solid phase transitions, and visualize kinetic pathways with single-particle resolution. We observe the formation of relatively ordered precursor structures with different symmetries, which then convert into metastable solids. During this conversion, two major cross-symmetry pathways always occur, regardless of the final state and the interaction potential. In addition, we find a broad decoupling of density variation and symmetry development, and discover that nucleation rarely starts from the densest regions. These findings hold for all of our samples, suggesting the possibility of finding a unified picture for the complex crystallization kinetics in colloidal systems.