A snowflake is either a single ice crystal or an aggregation of ice crystals. Viewed microscopically, they form interesting and wondrous crystal forms. Some researchers suggest that there can be up to 15 distinct crystal forms. However, none of the intriguing shapes and patterns can be called “square.”
To examine the behavior of water at the molecular level, with a view to improve water filtration, researchers have been looking at microscopic water droplets. The main focus has been on the tiny droplets that become trapped inside capillaries buried inside material. Very little is known about the structure that water at this level takes.
Scientists based at The University of Manchester, the University of Ulm in Germany, and the University of Science and Technology of China have developed a transparent nanoscale capillary to view and chart the structure of water locked inside. The nano-capillary was made from graphene – just one atom thick.
Graphene is remarkably strong for its very low weight (100 times stronger than steel and it conducts heat and electricity with great efficiency). The material is being investigated for many potential applications, including a new generation of quantum computers.
When the water was viewed microscopically, small square crystals of ice at room temperature were revealed and successive water molecules were arranged into a square lattice. This arrangement was a surprise to the researchers and hitherto an uncharacteristic structure for water.
Further investigation revealed that such a structure is not so uncommon. If a water layer is thin enough and the nanosphere around the water made of the right material, then square crystals are formed.
The inference is that water at the nano-scale behaves very differently to water at the bulk-level. This has implications for how water flows through filters and will be important for developing equipment to provide clean water in regions where water is not fit for human consumption.
The findings have been published in the journal Nature, in a paper called “Square ice in graphene nanocapillaries.”
