There are now 19 forms of ice, thanks to this discovery
Cheryl Santa Maria

3/12/2021


A recent study published in Nature Communications by researchers at the University of Innsbruck has identified the 19th form of water ice. A second paper by researchers in Japan has also been published, verifying the study.

It's no surprise that ice and water are versatile, and the way atoms and molecules are oriented create different forms. There were previously 18 known crystalline forms of water and they have different properties, depending on the temperature and pressure that created them.

The new discovery, dubbed ice XIX, hasn't been found in nature. The lab-created ice is 'exotic', the study's authors say, and important because it provides insight into the properties of previously-known forms.

"While conventional ice and snow are abundant on Earth, no other forms are found on the surface of our planet - except in research laboratories," the authors say in a statement.

"Many varieties of water ice are formed in the vastness of space under special pressure and temperature conditions. They are found, for example, on celestial bodies such as Jupiter's moon Ganymede, which is covered by layers of different ice varieties."

But one can't simply declare a new form of ice. There's a process involved, lead researcher Thomas Loerting, a professor of physical chemistry at the University of Innsbruck in Austria, told LiveScience.

It begins with clearly defining the crystal structure, a technical hurdle solved by Ph.D. student Tobias Gasser, who thought to add a percent of normal water to the heavy water - a strategy that substantially sped up ordering.

To define the crystal, Loerting's team had to determine the most basic repeating structure that had all of the atoms located within it. They also had to clarify the symmetry of the structure.

"Only if all of these are known, you are allowed to name your ice … Ice XIX is now the name for the new ice phase discovered in our work," Loerting told LiveScience.

SIBLING PAIRS

Provided by The Weather NetworkIllustration showing the relationship between the ice VI and XIX unit cells viewed down their c-axes, and the differences in their diffraction patterns, with colour coding red for ice XIX and blue for ice VI. Caption and photo: Uni Innsbruck

More than a decade ago, a variant of the new ice was discovered and named ice XV. Three years ago, Loerting's team changed XV's "manufacturing" by slowing down the cooling process and increasing the pressure, allowing them to arrange the hydrogen atoms in a way that produced XIX.

"Ice XV and ice XIX represents the first sibling pair in ice physics in which the oxygen lattice is the same, but the pattern how hydrogen atoms are ordered is different," the authors say in a statement.

"This also means that for the first time it will now be possible to realize the transition between two ordered ice forms in experiments," Loreting added.