EPJ E Highlight - How supercooled water is prevented from turning into ice

Representative configurations of ice in its Ic format, which is a simulation in a cube with 216 molecules, Ih format, which is in a rectangular cell with 432 molecules, and in liquid water

Calculating the energy barrier that keeps liquid water below zero from immediately turning into ice provides the key to understanding its ability to be compressed as temperature drops

Water behaves in mysterious ways. Especially below zero, where it is dubbed supercooled water, before it turns into ice. Physicists have recently observed the spontaneous first steps of the ice formation process, as tiny crystal clusters as small as 15 molecules start to exhibit the recognisable structural pattern of crystalline ice. This is part of a new study, which shows that liquid water does not become completely unstable as it becomes supercooled, prior to turning into ice crystals. The team reached this conclusion by proving that an energy barrier for crystal formation exists throughout the region in which supercooled water’s compressibility continues to rise. Previous work argued that this barrier vanished as the liquid gets colder. These findings have been published in EPJ E by Connor Buhariwalla from St. Francis Xavier University in Antigonish, Canada and colleagues.

Interestingly, liquid water becomes easier to compress, the colder it gets - unlike other substances, which become harder to compress as temperature drops. The origin of water’s compressibility behaviour has been debated for decades. One possible explanation - still unconfirmed—for this unusual phenomenon stems from the presence of a transition, similar to the liquid-gas transition found when water becomes vapour. The difference: in supercooled water the transition is from one phase of liquid to another, very similar, phase of liquid water, upon cooling.

The problem is that in a normal experiment, supercooled water crystallizes under the conditions at which the liquid-liquid phase transition is predicted to occur. Accordingly, the team instead examined a model describing the behaviour of supercooled water, in which previous work showed a phase transition. There, they calculated the so-called free energy cost for the formation of small ice crystal nuclei. These findings help explain why water can be found in two very different solid forms that do not exhibit a crystalline structure, unlike ice in a freezer, called low-density and high-density amorphous ice.

Free energy of formation of small ice nuclei near the Widom line in simulations of supercooled water. Connor R. C. Buhariwalla, Richard K. Bowles, Ivan Saika-Voivod, Francesco Sciortino, and Peter H. Poole (2015), Eur. Phys. J. E 38: 39, DOI 10.1140/epje/i2015-15039-x

This was our first experience of publishing with EPJ Web of Conferences. We contacted the publisher in the middle of September, just one month prior to the Conference, but everything went through smoothly. We have had published MNPS Proceedings with different publishers in the past, and would like to tell that the EPJ Web of Conferences team was probably the best, very quick, helpful and interactive. Typically, we were getting responses from EPJ Web of Conferences team within less than an hour and have had help at every production stage.
We are very thankful to Solange Guenot, Web of Conferences Publishing Editor, and Isabelle Houlbert, Web of Conferences Production Editor, for their support. These ladies are top-level professionals, who made a great contribution to the success of this issue. We are fully satisfied with the publication of the Conference Proceedings and are looking forward to further cooperation. The publication was very fast, easy and of high quality. My colleagues and I strongly recommend EPJ Web of Conferences to anyone, who is interested in quick high-quality publication of conference proceedings.

On behalf of the Organizing and Program Committees and Editorial Team of MNPS-2019, Dr. Alexey B. Nadykto, Moscow State Technological University “STANKIN”, Moscow, Russia. EPJ Web of Conferences vol. 224 (2019)

ISSN: 2100-014X (Electronic Edition)

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