Department of Physics, Tokyo Metropolitan University, 1-1 Minamioosawa, Hachiouji-shi, Tokyo, 192-0397, Japan.
Sci Rep. 2017 Jul 31;7(1):6912. doi: 10.1038/s41598-017-07352-z.
Understanding pattern formation during phase separation is a key topic in materials science for the important role that patterns play in determining macroscopic physical properties. In this work, we show how pattern formation can be controlled using a phase-separation trigger propagating outwards from a point. We found a range of patterns, including a random droplet pattern, a concentric pattern and a dendritic pattern, depending on the speed at which the trigger propagates, while only the random droplet pattern is observed in a system with homogeneous cooling. We also found that the phase at the core of the concentric pattern periodically changes with time. In addition, we investigated pattern formation during phase separation induced by multiple propagated triggers. When we propagate the triggers from periodic points in space, a metastable regular hexagonal pattern is formed. We also found a bifurcation between a case where the majority phase becomes a droplet phase and a case where the minority phase adopts a droplet pattern. We also confirm the existence of a percolated, bicontinuous phase, even with an asymmetric composition.
理解相分离过程中的图案形成是材料科学中的一个关键课题，因为图案在决定宏观物理性质方面起着重要作用。在这项工作中，我们展示了如何使用从一个点向外传播的相分离触发器来控制图案形成。我们发现了一系列图案，包括随机液滴图案、同心图案和树枝状图案，这取决于触发器传播的速度，而在均匀冷却的系统中只观察到随机液滴图案。我们还发现，同心图案核心处的相随时间周期性变化。此外，我们还研究了多个传播触发器引起的相分离过程中的图案形成。当我们从空间的周期性点传播触发器时，会形成一个亚稳的规则六边形图案。我们还发现，在大多数相变为液滴相的情况和少数相采用液滴图案的情况之间存在分岔。我们还证实了即使在组成不对称的情况下，也存在连通的双连续相。
