Editing Water (section)

==== Phases of ice and water ====
{{main|Ice}}
The normal form of ice on the surface of Earth is [[Ice Ih|ice I<sub>h</sub>]], a phase that forms crystals with [[Hexagonal crystal family|hexagonal symmetry]]. Another with [[Cubic crystal system|cubic crystalline symmetry]], [[Ice Ic|ice I<sub>c</sub>]], can occur in the upper atmosphere.<ref>{{cite journal |last1=Murray |first1=Benjamin J.|last2=Knopf |first2=Daniel A. |last3=Bertram |first3=Allan K. |year=2005|title=The formation of cubic ice under conditions relevant to Earth's atmosphere|journal=Nature|volume=434|pages=202–205|doi=10.1038/nature03403|pmid=15758996|issue=7030|bibcode=2005Natur.434..202M|s2cid=4427815}}</ref> As the pressure increases, ice forms other [[crystal structure]]s. As of 2024, twenty have been experimentally confirmed and several more are predicted theoretically.<ref>{{cite journal |last1=Salzmann |first1=Christoph G. |title=Advances in the experimental exploration of water's phase diagram |journal=The Journal of Chemical Physics |date=14 February 2019 |volume=150 |issue=6 |pages=060901 |doi=10.1063/1.5085163|pmid=30770019 |arxiv=1812.04333 |bibcode=2019JChPh.150f0901S |doi-access=free }}</ref> The eighteenth form of ice, [[ice XVIII]], a face-centred-cubic, superionic ice phase, was discovered when a droplet of water was subject to a shock wave that raised the water's pressure to millions of atmospheres and its temperature to thousands of degrees, resulting in a structure of rigid oxygen atoms in which hydrogen atoms flowed freely.<ref name="Sokol2021">{{cite magazine |url=https://www.wired.com/story/a-bizarre-form-of-water-may-exist-all-over-the-universe/ |title=A Bizarre Form of Water May Exist All Over the Universe |last=Sokol |first=Joshua |magazine=Wired |date=12 May 2019 |access-date=1 September 2021 |archive-url=https://web.archive.org/web/20190512130533/https://www.wired.com/story/a-bizarre-form-of-water-may-exist-all-over-the-universe/|archive-date=12 May 2019|url-status=live}}</ref><ref name="Millotetal2019">{{cite journal |last1=Millot |first1=M. |last2=Coppari |first2=F. |last3=Rygg |first3=J. R. |last4=Barrios |first4=Antonio Correa |last5=Hamel |first5=Sebastien |last6=Swift |first6=Damian C. |last7=Eggert |first7=Jon H. |year=2019 |title=Nanosecond X-ray diffraction of shock-compressed superionic water ice |journal=Nature |publisher=Springer |volume=569 |issue=7755 |pages=251–255 |doi=10.1038/s41586-019-1114-6 |pmid=31068720 |bibcode=2019Natur.569..251M |osti=1568026 |s2cid=148571419 |url=https://www.osti.gov/biblio/1568026 |access-date=5 March 2024 |archive-date=9 July 2023 |archive-url=https://web.archive.org/web/20230709172600/https://www.osti.gov/biblio/1568026 |url-status=live }}</ref> When sandwiched between layers of [[graphene]], ice forms a square lattice.<ref>{{cite journal |last1=Peplow |first1=Mark |title=Graphene sandwich makes new form of ice |journal=Nature |date=25 March 2015 |doi=10.1038/nature.2015.17175|s2cid=138877465 }}</ref>

The details of the chemical nature of liquid water are not well understood; some theories suggest that its unusual behavior is due to the existence of two liquid states.<ref name="NatureWaterStructure" /><ref>{{Cite journal |last1=Maestro |first1=L. M. |last2=Marqués |first2=M. I. |last3=Camarillo |first3=E. |last4=Jaque |first4=D. |last5=Solé |first5=J. García |last6=Gonzalo |first6=J. A. |last7=Jaque |first7=F. |last8=Valle |first8=Juan C. Del |last9=Mallamace |first9=F. |date=1 January 2016 |title=On the existence of two states in liquid water: impact on biological and nanoscopic systems |journal=International Journal of Nanotechnology |volume=13 |issue=8–9 |pages=667–677 |doi=10.1504/IJNT.2016.079670 |bibcode=2016IJNT...13..667M |s2cid=5995302 |archive-url=https://web.archive.org/web/20231115003311/http://pdfs.semanticscholar.org/fc61/afe755fe34c5e163daa3c402bb8f03c40d7f.pdf |archive-date=15 November 2023 |url-status=live |url=http://pdfs.semanticscholar.org/fc61/afe755fe34c5e163daa3c402bb8f03c40d7f.pdf |access-date=5 March 2024 }}</ref><ref>{{cite journal |first1=Francesco |last1=Mallamace |first2=Carmelo |last2=Corsaro |first3=H. Eugene |last3=Stanley |title=A singular thermodynamically consistent temperature at the origin of the anomalous behavior of liquid water|journal=Scientific Reports |date=18 December 2012 |volume=2 |issue=1 |page=993 |doi=10.1038/srep00993 |pmid=23251779 |pmc=3524791 |bibcode= 2012NatSR...2..993M}}</ref><ref>{{Cite journal |last1=Perakis |first1=Fivos |last2=Amann-Winkel |first2=Katrin |last3=Lehmkühler |first3=Felix |last4=Sprung |first4=Michael |last5=Mariedahl |first5=Daniel |last6=Sellberg |first6=Jonas A. |last7=Pathak |first7=Harshad |last8=Späh |first8=Alexander |last9=Cavalca |first9=Filippo|last10=Ricci|first10=Alessandro |last11=Jain |first11=Avni |last12=Massani |first12=Bernhard |last13=Aubree |first13=Flora |last14=Benmore |first14=Chris J. |last15=Loerting|author15-link=Thomas Loerting |first15=Thomas |last16=Grübel |first16=Gerhard |last17=Pettersson |first17=Lars G. M. |last18=Nilsson |first18=Anders |date=26 June 2017 |title=Diffusive dynamics during the high-to-low density transition in amorphous ice |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=13 |issue=8–9 |pages=667–677 |doi=10.1073/pnas.1705303114|pmc=5547632 |pmid=28652327|bibcode=2017PNAS..114.8193P |doi-access=free }}</ref>