Strain Relief during Ice Growth on a Hexagonal Template

Abstract

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.

Advances in Atomic Force Microscopy: Imaging of Two- and Three-Dimensional Interfacial Water

“…Meanwhile, at the monoatomic step edge of Ni(111), another water network is formed, containing pentagonal and octagonal rings along the step direction with a periodicity of four times Ni interatomic distance (4a 0 ) ( Figures 1C–F ). Such a periodic 1D pentagonal-octagonal network closely resembles the domain boundaries of H 2 O/Ru (0001) ( Maier et al, 2016 ), the water islands on stepped Cu(551) surface ( Lin et al, 2018 ), and the defect rows in the second water layer on SnPt (111) ( Gerrard et al, 2019 ). This indicates that the 1D pentagonal-octagonal network structure is a representative defect existing in the interfacial water layers on metal surfaces.…”

Molecular‐Level Encapsulation Strategy: Host–Guest‐Inclusion‐Complex‐Derived Carbon‐Encapsulated Nanocomposites for High Performance Lithium‐Ion Storage

“…The formation of the inclusion complex is confirmed by ultraviolet-visible adsorption spectra, X-ray powder diffraction (XRD), and Fourier transform infrared radiation (Figures S1-S3, Supporting Information). During the gradient freezing process from surface to interior, water-soluble β-CD inclusion molecules are repelled and compressed between the ice crystals due to the template effect of ice [32,33] and the self-assembly characteristics of cyclodextrin. [34,35] After freeze-drying, the powders expand and show a fluffy sheet-like appearance ( Figure S4, Supporting Information).…”

Advances in Atomic Force Microscopy: Weakly Perturbative Imaging of the Interfacial Water

“…Ice formation on exposed surfaces play critical roles in an incredibly broad spectrum of atmospheric science (Kiselev et al, 2017), materials science (Parent and Ilinca, 2011), biology (Graether et al, 2000), and planetary science (Head et al, 2003). However, the microscopic mechanisms of ice nucleation remain unclear (Gerrard et al, 2019). Experimental investigation of the ice formation with atomic precision remains to be a grand challenge so far, due to the short lifetimes of the intermediate structures and fragileness of the ice edges (Lupi et al, 2014).…”

“…Particularly, determining the transition from single layer to multilayer adsorption is a great challenge, because the structure and surface energy of the first water layer are generally quite different from that of a bulk ice film and the evolution from the 2D to 3D ice growth is complex. Although both SPM and spectroscopic techniques have been used to study multilayer growth, atomic scale characterization of H-bonds in ice structure and understanding of the ice growth process are still lacking (Thürmer and Nie, 2013; Gerrard et al, 2019). Development of advanced SPM techniques, particularly the weakly perturbative AFM imaging, is likely to play a considerable role in this area.…”