Superionic water

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Superionic ice rest.svg
In the absence of an applied electric field, H+ ions diffuse in the O2− lattice.
Superionic ice conducting.svg
When an electric field is applied, H+ ions migrate towards the anode.
A remarkable characteristic of superionic ice is its ability to act as a conductor.

Superionic water, also called superionic ice or ice XVIII, [1] is a phase of water that exists at extremely high temperatures and pressures. In superionic water, water molecules break apart and the oxygen ions crystallize into an evenly spaced lattice while the hydrogen ions float around freely within the oxygen lattice. [2] The freely mobile hydrogen ions make superionic water almost as conductive as typical metals, making it a superionic conductor. [1] It is one of the 19 known crystalline phases of ice. Superionic water is distinct from ionic water, which is a hypothetical liquid state characterized by a disordered soup of hydrogen and oxygen ions.

Contents

While theorized for decades, it was not until the 1990s that the first experimental evidence emerged for superionic water. Initial evidence came from optical measurements of laser-heated water in a diamond anvil cell, [3] and from optical measurements of water shocked by extremely powerful lasers. [4] The first definitive evidence for the crystal structure of the oxygen lattice in superionic water came from x-ray measurements on laser-shocked water which were reported in 2019. [1]

If it were present on the surface of the Earth, superionic ice would rapidly decompress. In May 2019, scientists at the Lawrence Livermore National Laboratory (LLNL) were able to synthesize superionic ice, confirming it to be almost four times as dense as normal ice and black in color. [5] [4] [6]

Superionic water is theorized to be present in the mantles of giant planets such as Uranus and Neptune. [7] [8]

Properties

As of 2013, it is theorized that superionic ice can possess two crystalline structures. At pressures in excess of 50  GPa (7,300,000 psi) it is predicted that superionic ice would take on a body-centered cubic structure. However, at pressures in excess of 100 GPa, and temperatures above 2000 K, it is predicted that the structure would shift to a more stable face-centered cubic lattice. [9] The ice appears black in color. [4] [10]

History of theoretical and experimental evidence

Demontis et al. made the first prediction for superionic water using classical molecular dynamics simulations in 1988. [11] In 1999, Cavazzoni et al. predicted that such a state would exist for ammonia and water in conditions such as those existing on Uranus and Neptune. [12] In 2005 Laurence Fried led a team at Lawrence Livermore National Laboratory to recreate the formative conditions of superionic water. Using a technique involving smashing water molecules between diamonds and super heating it with lasers they observed frequency shifts which indicated that a phase transition had taken place. The team also created computer models which indicated that they had indeed created superionic water. [8] In 2013 Hugh F. Wilson, Michael L. Wong, and Burkhard Militzer at the University of California, Berkeley published a paper predicting the face-centered cubic lattice structure that would emerge at higher pressures. [9]

Additional experimental evidence was found by Marius Millot and colleagues in 2018 by inducing high pressure on water between diamonds and then shocking the water using a laser pulse. [4] [13]

2018–2019 experiments

In 2018, researchers at LLNL squeezed water between two pieces of diamond with a pressure of 2,500  MPa (360,000 psi). The water was squeezed into type VII ice, which is 60 percent denser than normal water. [14]

The compressed ice was then transported to the University of Rochester where it was blasted by a pulse of laser light. The reaction created conditions like those inside of ice giants such as Uranus and Neptune by heating up the ice thousands of degrees under a pressure a million times greater than the Earth's atmosphere in only 10 to 20 billionths of a second. The experiment concluded that the current in the conductive water was indeed carried by ions rather than electrons and thus pointed to the water being superionic. [14] More recent experiments from the same Lawrence Livermore National Laboratory team used x-ray crystallography on laser-shocked water droplets to determine that the oxygen ions enter a face-centered-cubic phase, which was dubbed ice XVIII and reported in the journal Nature in May 2019. [1]

Existence in ice giants

It is theorized that the ice giant planets Uranus and Neptune hold a layer of superionic water. [15] Machine learning and free-energy methods predict close-packed superionic phases to be stable over a wide temperature and pressure range, and a body-centred cubic superionic phase to be kinetically favoured, but stable over a small window of parameters. [16]

On the other hand, there are also studies that suggest that other elements present inside the interiors of these planets, particularly carbon, may prevent the formation of superionic water. [17] [18]

Related Research Articles

<span class="mw-page-title-main">Giant planet</span> Planet much larger than the Earth

A giant planet is a diverse type of planet much larger than Earth. They are usually primarily composed of low-boiling point materials (volatiles), rather than rock or other solid matter, but massive solid planets can also exist. There are four known giant planets in the Solar System: Jupiter, Saturn, Uranus, and Neptune. Many extrasolar giant planets have been identified as orbiting other stars.

<span class="mw-page-title-main">Uranus</span> Seventh planet from the Sun

Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a supercritical phase of matter, which in astronomy is called 'ice' or volatiles. The planet's atmosphere has a complex layered cloud structure and has the lowest minimum temperature of 49 K out of all the Solar System's planets. It has a marked axial tilt of 82.23° with a retrograde rotation period of 17 hours and 14 minutes. This means that in an 84-Earth-year orbital period around the Sun, its poles get around 42 years of continuous sunlight, followed by 42 years of continuous darkness.

Metallic hydrogen is a phase of hydrogen in which it behaves like an electrical conductor. This phase was predicted in 1935 on theoretical grounds by Eugene Wigner and Hillard Bell Huntington.

<span class="mw-page-title-main">Allotropes of carbon</span> Materials made only out of carbon

Carbon is capable of forming many allotropes due to its valency. Well-known forms of carbon include diamond and graphite. In recent decades, many more allotropes have been discovered and researched, including ball shapes such as buckminsterfullerene and sheets such as graphene. Larger-scale structures of carbon include nanotubes, nanobuds and nanoribbons. Other unusual forms of carbon exist at very high temperatures or extreme pressures. Around 500 hypothetical 3‑periodic allotropes of carbon are known at the present time, according to the Samara Carbon Allotrope Database (SACADA).

<span class="mw-page-title-main">Magnesium peroxide</span> Chemical compound

Magnesium peroxide (MgO2) is an odorless fine powder peroxide with a white to off-white color. It is similar to calcium peroxide because magnesium peroxide also releases oxygen by breaking down at a controlled rate with water. Commercially, magnesium peroxide often exists as a compound of magnesium peroxide and magnesium hydroxide.

<span class="mw-page-title-main">Ice giant</span> Giant planet primarily consisting of compounds with freezing points exceeding 100°K

An ice giant is a giant planet composed mainly of elements heavier than hydrogen and helium, such as oxygen, carbon, nitrogen, and sulfur. There are two ice giants in the Solar System: Uranus and Neptune.

<span class="mw-page-title-main">Ocean world</span> Planet containing a significant amount of water or other liquid

An ocean world, ocean planet or water world is a type of planet that contains a substantial amount of water in the form of oceans, as part of its hydrosphere, either beneath the surface, as subsurface oceans, or on the surface, potentially submerging all dry land. The term ocean world is also used sometimes for astronomical bodies with an ocean composed of a different fluid or thalassogen, such as lava, ammonia or hydrocarbons. The study of extraterrestrial oceans is referred to as planetary oceanography.

Ice I<sub>c</sub> Metastable cubic crystalline variant of ice

Ice Ic is a metastable cubic crystalline variant of ice. Hans König was the first to identify and deduce the structure of ice Ic. The oxygen atoms in ice Ic are arranged in a diamond structure and is extremely similar to ice Ih having nearly identical densities and the same lattice constant along the hexagonal puckered-planes. It forms at temperatures between 130 and 220 kelvins upon cooling, and can exist up to 240 K (−33 °C) upon warming, when it transforms into ice Ih.

<span class="mw-page-title-main">Ice XI</span> Alternative state of water ice

Ice XI is the hydrogen-ordered form of Ih, the ordinary form of ice. Different phases of ice, from ice II to ice XIX, have been created in the laboratory at different temperatures and pressures. The total internal energy of ice XI is about one sixth lower than ice Ih, so in principle it should naturally form when ice Ih is cooled to below 72 K. The low temperature required to achieve this transition is correlated with the relatively low energy difference between the two structures. Water molecules in ice Ih are surrounded by four semi-randomly directed hydrogen bonds. Such arrangements should change to the more ordered arrangement of hydrogen bonds found in ice XI at low temperatures, so long as localized proton hopping is sufficiently enabled; a process that becomes easier with increasing pressure. Correspondingly, ice XI is believed to have a triple point with hexagonal ice and gaseous water at.

<span class="mw-page-title-main">Extraterrestrial atmosphere</span> Area of astronomical research

The study of extraterrestrial atmospheres is an active field of research, both as an aspect of astronomy and to gain insight into Earth's atmosphere. In addition to Earth, many of the other astronomical objects in the Solar System have atmospheres. These include all the gas giants, as well as Mars, Venus and Titan. Several moons and other bodies also have atmospheres, as do comets and the Sun. There is evidence that extrasolar planets can have an atmosphere. Comparisons of these atmospheres to one another and to Earth's atmosphere broaden our basic understanding of atmospheric processes such as the greenhouse effect, aerosol and cloud physics, and atmospheric chemistry and dynamics.

<span class="mw-page-title-main">Ice VII</span> Alternative state of water ice

Ice VII is a cubic crystalline form of ice. It can be formed from liquid water above 3 GPa (30,000 atmospheres) by lowering its temperature to room temperature, or by decompressing heavy water (D2O) ice VI below 95 K. (Different types of ice, from ice II to ice XVIII, have been created in the laboratory at different temperatures and pressures. Ordinary water ice is known as ice Ih in the Bridgman nomenclature.) Ice VII is metastable over a wide range of temperatures and pressures and transforms into low-density amorphous ice (LDA) above 120 K (−153 °C). Ice VII has a triple point with liquid water and ice VI at 355 K and 2.216 GPa, with the melt line extending to at least 715 K (442 °C) and 10 GPa. Ice VII can be formed within nanoseconds by rapid compression via shock-waves. It can also be created by increasing the pressure on ice VI at ambient temperature. At around 5 GPa, Ice VII becomes the tetragonal Ice VIIt.

<span class="mw-page-title-main">Octaoxygen</span> Allotrope of oxygen

Octaoxygen, also known as ε-oxygen or red oxygen, is an allotrope of oxygen consisting of eight oxygen atoms. This allotrope forms above 600 K at pressures greater than 17 GPa.

<span class="mw-page-title-main">Neptune</span> Eighth planet from the Sun

Neptune is the eighth and farthest known planet from the Sun. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth, and slightly more massive than fellow ice giant Uranus. Neptune is denser and physically smaller than Uranus because its greater mass causes more gravitational compression of its atmosphere. Being composed primarily of gases and liquids, it has no well-defined solid surface. The planet orbits the Sun once every 164.8 years at an orbital distance of 30.1 astronomical units. It is named after the Roman god of the sea and has the astronomical symbol , representing Neptune's trident.

<span class="mw-page-title-main">Nice model</span> Scenario for the dynamical evolution of the Solar System

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<span class="mw-page-title-main">Gas giant</span> Giant planet mainly composed of light elements

A gas giant is a giant planet composed mainly of hydrogen and helium. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" was originally synonymous with "giant planet". However, in the 1990s, it became known that Uranus and Neptune are really a distinct class of giant planets, being composed mainly of heavier volatile substances. For this reason, Uranus and Neptune are now often classified in the separate category of ice giants.

Planetary oceanography, also called astro-oceanography or exo-oceanography, is the study of oceans on planets and moons other than Earth. Unlike other planetary sciences like astrobiology, astrochemistry, and planetary geology, it only began after the discovery of underground oceans in Saturn's moon Titan and Jupiter's moon Europa. This field remains speculative until further missions reach the oceans beneath the rock or ice layer of the moons. There are many theories about oceans or even ocean worlds of celestial bodies in the Solar System, from oceans made of diamond in Neptune to a gigantic ocean of liquid hydrogen that may exist underneath Jupiter's surface.

<span class="mw-page-title-main">Solid nitrogen</span> Solid form of the 7th element

Solid nitrogen is a number of solid forms of the element nitrogen, first observed in 1884. Solid nitrogen is mainly the subject of academic research, but low-temperature, low-pressure solid nitrogen is a substantial component of bodies in the outer Solar System and high-temperature, high-pressure solid nitrogen is a powerful explosive, with higher energy density than any other non-nuclear material.

Although diamonds on Earth are rare, extraterrestrial diamonds are very common. Diamonds small enough that they contain only about 2000 carbon atoms are abundant in meteorites and some of them formed in stars before the Solar System existed. High pressure experiments suggest large amounts of diamonds are formed from methane on the ice giant planets Uranus and Neptune, while some planets in other planetary systems may be almost pure diamond. Diamonds are also found in stars and may have been the first mineral ever to have formed.

<span class="mw-page-title-main">William J. Nellis</span> American physicist

William J. Nellis is an American physicist. He is an Associate of the Physics Department of Harvard University. His work has focused on ultra-condensed matter at extreme pressures, densities and temperatures achieved by fast dynamic compression. He is most well-known for the first experimental observation of a metallic phase of dense hydrogen, a material predicted to exist by Eugene Wigner and Hillard Bell Huntington in 1935.

Trihydrogen oxide is a predicted inorganic compound of hydrogen and oxygen with the chemical formula H3O. This is still a hypothetical compound, one of the unstable hydrogen polyoxides. It is forecasted that the compound could constitute a thin layer of metallic liquid around the cores of Uranus and Neptune, being the source of their magnetic fields. Calculations indicate the stability of H3O in solid, superionic, and fluid metallic states at the deep interior conditions of these planets.

References

  1. 1 2 3 4 Millot, Marius; Coppari, Federica; Rygg, J. Ryan; Correa Barrios, Antonio; Hamel, Sebastien; Swift, Damian C.; Eggert, Jon H. (8 May 2019). "Nanosecond X-ray diffraction of shock-compressed superionic water ice". Nature. 569 (7755): 251–255. doi:10.1038/s41586-019-1114-6. OSTI   1568026. PMID   31068720. S2CID   256768272.
  2. ↑ Weird water lurking inside giant planets, New Scientist,01 September 2010, Magazine issue 2776.
  3. ↑ Goncharov, Alexander F.; et al. (2005). "Dynamic Ionization of Water under Extreme Conditions" (PDF). Phys. Rev. Lett. 94 (12): 125508. doi:10.1103/PhysRevLett.94.125508. PMID   15903935.
  4. 1 2 3 4 Millot, Marius; et al. (5 February 2018). "Experimental evidence for superionic water ice using shock compression". Nature Physics . 14 (3): 297–302. Bibcode:2018NatPh..14..297M. doi:10.1038/s41567-017-0017-4. OSTI   1542614. S2CID   256703104.
  5. ↑ Valich, Lindsey. "'Exotic' form of ice both solid and liquid". University of Rochester.
  6. ↑ Sokol, Joshua (12 May 2019). "A Bizarre Form of Water May Exist All Over the Universe". Wired. ISSN   1059-1028 . Retrieved 13 May 2019.
  7. ↑ Chang, Kenneth (5 February 2018). "Newly Discovered Form of Water Ice Is 'Really Strange' – Long theorized to be found in the mantles of Uranus and Neptune, the confirmation of the existence of superionic ice could lead to the development of new materials". The New York Times . Retrieved 5 February 2018.
  8. 1 2 Marris, Emma (22 March 2005). "Giant planets may host superionic water". Nature. doi:10.1038/news050321-4.
  9. 1 2 Phys.org, "New phase of water could dominate the interiors of Uranus and Neptune", Lisa Zyga, 25 April 2013
  10. ↑ Sokol, Joshua (12 May 2019). "A Bizarre Form of Water May Exist All Over the Universe". Wired. ISSN   1059-1028 . Retrieved 13 May 2019.
  11. ↑ Demontis, P.; et al. (1988). "New high-pressure phases of ice" (PDF). Phys. Rev. Lett. 60 (22): 2284–2287. doi:10.1103/PhysRevLett.60.2284. PMID   10038311.
  12. ↑ Cavazzoni, C.; et al. (1999). "Superionic and Metallic States of Water and Ammonia at Giant Planet Conditions". Science. 283 (5398): 44–46. Bibcode:1999Sci...283...44C. doi:10.1126/science.283.5398.44. PMID   9872734. S2CID   11938710.
  13. ↑ Sokol, Joshua (12 May 2019). "A Bizarre Form of Water May Exist All Over the Universe". Wired. ISSN   1059-1028 . Retrieved 13 May 2019.
  14. 1 2 Chang, Kenneth (5 February 2018). "New Form of Water, Both Liquid and Solid, Is 'Really Strange'". The New York Times. ISSN   0362-4331 . Retrieved 13 February 2018.
  15. ↑ Charlie Osolin. "Public Affairs Office: Recreating the Bizarre State of Water Found on Giant Planets". Llnl.gov. Retrieved 24 December 2010.
  16. ↑ Cheng, Bingqing; Bethkenhagen, Mandy; Pickard, Chris J.; Hamel, Sebastien (2021). "Phase behaviours of superionic water at planetary conditions". Nature Physics. 17 (11): 1228–1232. arXiv: 2103.09035 . doi:10.1038/s41567-021-01334-9. S2CID   232240463.
  17. ↑ Chau, Ricky; Hamel, Sebastien; Nellis, William J. (2011). "Chemical processes in the deep interior of Uranus". Nat. Commun. 2. Article number: 203. doi: 10.1038/ncomms1198 . PMID   21343921.
  18. ↑ Wang, Yanchao (29 November 2011). "High pressure partially ionic phase of water ice". Nature Communications. 2: 563. doi: 10.1038/ncomms1566 . PMID   22127059.
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