Gispen Willem, Dijkstra Marjolein
Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht 3584 CC, The Netherlands.
Phys Rev Lett. 2022 Aug 26;129(9):098002. doi: 10.1103/PhysRevLett.129.098002.
We determine the kinetic phase diagram for nucleation and growth of crystal phases in a suspension of charged colloids. Exploiting the seeding approach in extensive simulations, we calculate nucleation barrier heights for face-centered cubic (fcc) and body-centered cubic (bcc) phases for varying screening lengths and supersaturations. We determine for the entire metastable fluid region the crystal polymorph with the lowest nucleation barrier, and find a regime close to the triple point where metastable bcc can form due to a lower nucleation barrier, even though fcc is the stable phase. For higher supersaturation, we find that the difference in barrier heights decreases and we observe a mix of hexagonal close-packed, fcc, and bcc structures in the growth of crystalline seeds as well as in spontaneously formed crystals. Our kinetic phase diagram rationalizes the different crystallization mechanisms observed in previous work.
我们确定了带电胶体悬浮液中晶相形核与生长的动力学相图。通过在广泛的模拟中采用晶种法，我们计算了面心立方（fcc）和体心立方（bcc）相在不同屏蔽长度和过饱和度下的形核势垒高度。我们确定了整个亚稳流体区域中形核势垒最低的晶体多晶型，并发现了一个接近三相点的区域，在该区域中，尽管fcc是稳定相，但由于形核势垒较低，亚稳bcc仍可形成。对于更高的过饱和度，我们发现势垒高度的差异减小，并且在晶种生长以及自发形成的晶体中，我们观察到六方密堆积、fcc和bcc结构的混合。我们的动力学相图解释了先前工作中观察到的不同结晶机制。
