The Koyal Group Info Mag on Unusual square ice discovered
The surprising discovery of "square ice" which forms at room temperature was made by an international team of researchers last week.
The study was published in Nature by a team of scientists from UK and Germany led by Andre Geim of University of Manchester and G. Algara-Siller of University of Ulm. The accompanying review article was done by Alan Soper of Rutherford Appleton Laboratory in UK.
"We didn't expect to find square ice ... We found there is something strange in terms of water going through [nanochannels]. It's going too fast. And you can't explain that by just imagining a very thin layer of liquid. Liquids do not behave in that way. The important thing to realize is that it is ice in the sense of a crystallized structure, it's not ice in the familiar sense in that it's something cold and from which you have to protect yourself," said Professor Irina Grigorieva, one of the researchers.
To study the molecular structure of water inside a transparent nanoscale capillary, the team used electron microscopy. This enabled them to view individual water molecules, especially because the nano-capillary was created from graphene which was one atom thick and would not impair the electron imaging. Graphene was also chosen because it has unusual properties like conducting electricity and extreme strength. It's a 2D form of carbon that once rolled up in cylinders will form a carbon nanotube, a material, which according to The Koyal Group Info Mag, is a subject of further study because of its unusual strength.
The scientists themselves were admittedly surprised at finding out that small square-shaped ice crystals formed at room temperature where the graphene capillaries are narrow (3 atomic layers of water at most). The water molecules formed into square lattices arranged in neat rows -- an arrangement that is uncharacteristic for the element that is known for forming consistent triangular structures inside regular ice. This discovery may just be the first example of water behavior in nanostructure.
The Koyal Group Info Mag reports that scientists have been trying to understand for decades how water structure is affected when it is confined in narrow channels. It is only now that this becomes possible through computer simulations, but even with those, the results they get do not agree with each other.
The team is also trying to determine how common this square ice actually is by using computer simulations. And from what they've learned, if the water layer is thin enough, it could create a square ice regardless of the chemical properties of the nanopore's walls where it is confined. Since there is water practically everywhere -- in microscopic pores and monolayers on surfaces -- it is likely that square ice is actually very common in nature.
Aside from its more practical applications in water distillation, desalination and filtration, their finding also allows for a better understanding of how water behave at a molecular scale which is important in nanotechnology work.