How do Quasi-Liquid Layers Emerge from Ice Crystal Surfaces?
How do Quasi-Liquid Layers Emerge from Ice Crystal Surfaces?
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准液态层是如何从冰晶表面出现的？
DOI：
10.1021/cg400086j
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发表时间：
2013
影响因子：
3.8
通讯作者：
and Yoshinori Furukawa
中科院分区：
文献类型：
--
作者：
Gen Sazaki;Harutoshi Asakawa;Ken Nagashima;Shunichi Nakatsubo;and Yoshinori Furukawa
冰晶表面在低于0 °C的温度下融化，然后形成准液体层（QLL）。然而，揭示QLL的动态行为，这主导了冰晶在熔点附近的温度下的表面性质，仍然是一个实验挑战。在这里，我们展示了两种类型的QLL相，表现出不同的形态和动力学的生成机制的异同。我们通过先进的光学显微镜直接观察了冰基面上的圆形液体状液滴（α-QLL）和薄液体状层（β-QLL）的外观，这可以使基面上的单个基本步骤可视化。我们发现α-QLL总是出现在位错的露头处，而β-QLL则出现在镶嵌有许多微缺陷的晶体表面。这些结果清楚地证明了应变诱导两种类型的QLL出现的相似功能。我们还发现，当α-QLL的直径变得大于几十微米时，β-QLL自发地形成于基底面和α-QLL之间的界面处。这一结果源于α-和β-QLL的不同结构：β-QLL可能具有介于基面和α-QLL之间的结构，导致总界面自由能降低。
Ice crystal surfaces melt at temperatures below 0 °C, and then quasi-liquid layers (QLLs) are formed. However, revealing the dynamic behavior of QLLs, which dominates the surface properties of ice crystals at temperatures near the melting point, remains an experimental challenge. Here, we demonstrate the similarities and differences in the generation mechanisms of two types of QLL phases, which show different morphologies and dynamics. We directly visualized the appearance of round liquidlike droplets (α-QLLs) and thin liquidlike layers (β-QLLs) on ice basal faces by advanced optical microscopy, which can allow visualization of the individual elementary steps on basal faces. We found that α-QLLs always appear at outcrops of dislocations, and that β-QLLs emerge from crystal surfaces where many microdefects are embedded. These results clearly demonstrate the similar function that strain induces the appearance of both types of QLLs. We also found that β-QLLs are spontaneously formed at interfaces between basal faces and α-QLLs, when the diameter of the α-QLLs becomes larger than several tens of micrometers. This result arose from the different structures of α- and β-QLLs: the β-QLLs probably have a structure intermediate between those of basal faces and α-QLLs, resulting in a reduction of the total interfacial free energy.