Editing Phase transition (section)

===Other examples===
[[File:Argon ice 1.jpg|thumb|A small piece of rapidly melting solid [[argon]] shows two concurrent phase changes. The transition from solid to liquid, and gas to liquid (shown by the white condensed water vapour).]]
Other phase changes include:

* Transition to a [[mesophase]] between solid and liquid, such as one of the "[[liquid crystal]]" phases.
* The dependence of the [[adsorption]] geometry on coverage and temperature, such as for [[hydrogen]] on iron (110).
* The emergence of [[superconductivity]] in certain metals and ceramics when cooled below a critical temperature.
* The emergence of [[metamaterial]] properties in artificial photonic media as their parameters are varied.<ref>{{cite journal|author=Rybin, M.V.|title= Phase diagram for the transition from photonic crystals to dielectric metamaterials|journal=Nature Communications|page=10102 |year=2015|doi=10.1038/ncomms10102|pmid= 26626302 |display-authors=etal|volume=6|pmc=4686770|arxiv= 1507.08901|bibcode= 2015NatCo...610102R}}</ref><ref>Eds. Zhou, W., and Fan. S., [https://www.sciencedirect.com/bookseries/semiconductors-and-semimetals/vol/100/suppl/C Semiconductors and Semimetals. Vol 100. Photonic Crystal Metasurface Optoelectronics''], Elsevier, 2019</ref>
* Quantum condensation of [[boson]]ic fluids ([[Bose–Einstein condensate|Bose–Einstein condensation]]). The [[superfluidity|superfluid]] transition in liquid [[helium]] is an example of this.
* The [[Symmetry breaking|breaking of symmetries]] in the laws of physics during the early history of the universe as its temperature cooled.
* [[Isotope fractionation]] occurs during a phase transition, the ratio of light to heavy isotopes in the involved molecules changes. When [[water vapor]] condenses (an [[equilibrium fractionation]]), the heavier water isotopes (<sup>18</sup>O and <sup>2</sup>H) become enriched in the liquid phase while the lighter isotopes (<sup>16</sup>O and <sup>1</sup>H) tend toward the vapor phase.<ref>{{cite web
 | year=2004
 | author= Carol Kendall|author-link=Carol Kendall (scientist)
 | title= Fundamentals of Stable Isotope Geochemistry
 | url= http://wwwrcamnl.wr.usgs.gov/isoig/res/funda.html
 | publisher= USGS
 | access-date= 10 April 2014
}}</ref>

Phase transitions occur when the [[thermodynamic free energy]] of a system is [[analytic function|non-analytic]] for some choice of thermodynamic variables (cf. [[phase (matter)|phases]]). This condition generally stems from the interactions of a large number of particles in a system, and does not appear in systems that are small. Phase transitions can occur for non-thermodynamic systems, where temperature is not a parameter. Examples include: [[quantum phase transition]]s, dynamic phase transitions, and topological (structural) phase transitions. In these types of systems other parameters take the place of temperature. For instance, connection probability replaces temperature for percolating networks.
{{Condensed matter physics|expanded=States of matter}}