? ?? ?? ?？ In the last century, humans have discovered 18 three-dimensional structures of ice, the most common of which are hexagonal ice phases, such as falling snowflakes, summer ice, and thick Antarctic ice. But whether there is a stable existence of two-dimensional ice in nature has been lack of exact experimental evidence. Using high-resolution qplus atomic force microscopy, the team from peking university, university of nebraska lincoln and the chinese academy of sciences confirmed the existence of two-dimensional ice for the first time, and captured the formation of two-dimensional ice at atomic-level resolution, revealing its special growth mechanism. The results were published in the world's top academic journal Nature on the 2nd.
? ?? ?? ?？ In this study, researchers precisely controlled the temperature and water pressure, on the hydrophobic gold substrate, the first growth of this single crystal two-dimensional ice structure. They applied non-intrusive atomic force microscopy to submolecular-level resolution imaging of two-dimensional ice and combined with theoretical calculations to determine its atomic structure.
? ?? ?? ?？ "The results show that the two-dimensional ice is composed of two layers of hexagonal ice without rotating stacking, and the two layers are connected by hydrogen bonds. Each water molecule forms three hydrogen bonds with the water molecule of the same layer and one hydrogen bond with the water molecule of the upper and lower layers. Jiang Ying, a co-author of the article and a professor at the Center for Quantum Materials Science at Peking University, said it was also the first experimentally confirmed two-dimensional ice structure, which researchers named "two-dimensional ice phase I."
? ?? ?? ?？ How can we see the formation of two-dimensional ice? Researchers frozen two-dimensional ice from minus 153 degrees celsius to minus 268 degrees celsius, frozen a series of intermediate states during ice growth, and made a stable imaging of it, proposing a "bridging" growth mechanism for the zigzag boundary of two-dimensional iceland and a "sowing" growth mechanism for the armchair boundary.
? ?? ?? ?？ The discovery of two-dimensional ice not only challenges the traditional understanding of ice phase for more than 100 years, but also has a broad application prospect. "If two-dimensional ice exists, three-dimensional ice will grow very firmly against the surface. But if there is no two-dimensional ice, the formed three-dimensional ice and the surface contact surface is very small, it is easy to be blown away by the wind. We can design and develop anti-icing materials based on the structure of two-dimensional ice. Jiang Ying believes that using two-dimensional ice can reduce the friction between materials. In addition, two-dimensional ice can be used as a special two-dimensional material to provide a new platform for the study of high-temperature superconductivity, deep ultraviolet detection, freezing electron microscopy imaging and so on. (Golden Phoenix)