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Strain relief during ice growth on a hexagonal template
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2019-04-26 , DOI: 10.1021/jacs.9b03311 Nikki Gerrard 1 , Chiara Gattinoni 2 , Fiona McBride 1 , Angelos Michaelides 3 , Andrew Hodgson 1
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2019-04-26 , DOI: 10.1021/jacs.9b03311 Nikki Gerrard 1 , Chiara Gattinoni 2 , Fiona McBride 1 , Angelos Michaelides 3 , Andrew Hodgson 1
Affiliation
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Heterogeneous ice nucleation at solid surfaces impacts many areas of science, from environmental processes, such as precipitation, to microbiological systems and food processing, but the microscopic mechanisms underpinning nucleation remain unclear. Discussion of ice growth has often focused around the role of the surface in templating the structure of water, forcing the first layer to adopt the registry of the underlying substrate rather than that of ice. To grow a thick ice film, water in the first few ice layers must accommodate this strain, but understanding how this occurs requires detailed molecular-scale information that is lacking. Here we combine scanning tunneling microscopy, low-energy electron diffraction, and work-function measurements with electronic structure calculations to investigate the initial stages of ice growth on a Pt alloy surface, having a lattice spacing 6% larger than ice. Although the first layer of water forms a strictly commensurate hexagonal network, this behavior does not extend to the second layer. Instead, water forms a 2D structure containing extended defect rows made from face-sharing pentamer and octamer rings. The defect rows allow the majority of second-layer water to remain commensurate with the solid surface while compensating lateral strain by increasing the water density close to that of an ice surface. The observation of octamer–pentamer rows in ice films formed on several surfaces suggests that the octamer–pentamer defect motif acts as a flexible strain relief mechanism in thin ice films, providing a mechanism that is not available during the growth of strained films in other materials, such as semiconductors.
中文翻译：
六边形模板上冰生长过程中的应力消除
固体表面的异质冰成核影响着许多科学领域，从降水等环境过程到微生物系统和食品加工，但支撑成核的微观机制仍不清楚。关于冰生长的讨论通常集中在表面在模拟水结构中的作用，迫使第一层采用下面基底的注册而不是冰的注册。为了形成厚厚的冰膜，前几个冰层中的水必须适应这种压力，但了解这种情况是如何发生的需要详细的分子尺度信息，而目前尚缺乏这种信息。在这里，我们将扫描隧道显微镜、低能电子衍射、功函数测量与电子结构计算相结合，研究 Pt 合金表面上冰生长的初始阶段，其晶格间距比冰大 6%。尽管第一层水形成了严格相称的六边形网络，但这种行为并没有延伸到第二层。相反，水形成了一种二维结构，其中包含由共享面的五聚体和八聚体环组成的延伸缺陷行。缺陷行允许大部分第二层水保持与固体表面相称，同时通过增加接近冰表面的水密度来补偿横向应变。对多个表面上形成的冰膜中八聚体-五聚体行的观察表明，八聚体-五聚体缺陷基序在薄冰膜中充当灵活的应变消除机制，提供了在其他材料中应变膜的生长过程中不可用的机制，例如半导体。
更新日期：2019-04-26
中文翻译：
六边形模板上冰生长过程中的应力消除
固体表面的异质冰成核影响着许多科学领域，从降水等环境过程到微生物系统和食品加工，但支撑成核的微观机制仍不清楚。关于冰生长的讨论通常集中在表面在模拟水结构中的作用，迫使第一层采用下面基底的注册而不是冰的注册。为了形成厚厚的冰膜，前几个冰层中的水必须适应这种压力，但了解这种情况是如何发生的需要详细的分子尺度信息，而目前尚缺乏这种信息。在这里，我们将扫描隧道显微镜、低能电子衍射、功函数测量与电子结构计算相结合，研究 Pt 合金表面上冰生长的初始阶段，其晶格间距比冰大 6%。尽管第一层水形成了严格相称的六边形网络，但这种行为并没有延伸到第二层。相反，水形成了一种二维结构，其中包含由共享面的五聚体和八聚体环组成的延伸缺陷行。缺陷行允许大部分第二层水保持与固体表面相称，同时通过增加接近冰表面的水密度来补偿横向应变。对多个表面上形成的冰膜中八聚体-五聚体行的观察表明，八聚体-五聚体缺陷基序在薄冰膜中充当灵活的应变消除机制，提供了在其他材料中应变膜的生长过程中不可用的机制，例如半导体。
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