metallic hydrogen
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Metallic hydrogen is a
phase Phase or phases may refer to: Science *State of matter, or phase, one of the distinct forms in which matter can exist *Phase (matter), a region of space throughout which all physical properties are essentially uniform * Phase space, a mathematic ...
of
hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
in which it behaves like an
electrical conductor In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. Electric current is gener ...
. This phase was predicted in 1935 on theoretical grounds by
Eugene Wigner Eugene Paul "E. P." Wigner ( hu, Wigner Jenő Pál, ; November 17, 1902 – January 1, 1995) was a Hungarian-American theoretical physicist who also contributed to mathematical physics. He received the Nobel Prize in Physics in 1963 "for his con ...
and
Hillard Bell Huntington Dr. Hillard Bell Huntington (21 December 1910 in Wilkes Barre, Luzerne County, Pennsylvania – 17 July 1992 Troy, Rensselaer County, New York) was a physicist who (together with Eugene Wigner) first proposed, in 1935, that hydrogen could occur in a ...
. At
high pressure In science and engineering the study of high pressure examines its effects on materials and the design and construction of devices, such as a diamond anvil cell, which can create high pressure. By ''high pressure'' is usually meant pressures of th ...
and temperatures, metallic hydrogen can exist as a partial
liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...
rather than a
solid Solid is one of the State of matter#Four fundamental states, four fundamental states of matter (the others being liquid, gas, and Plasma (physics), plasma). The molecules in a solid are closely packed together and contain the least amount o ...
, and researchers think it might be present in large quantities in the hot and gravitationally compressed interiors of
Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...
and
Saturn Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...
, as well as in some
exoplanets An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...
.


Theoretical predictions


Hydrogen under pressure

Though often placed at the top of the
alkali metal The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K),The symbols Na and K for sodium and potassium are derived from their Latin names, ''natrium'' and ''kalium''; these are still the origins of the names ...
column in the
periodic table The periodic table, also known as the periodic table of the (chemical) elements, is a rows and columns arrangement of the chemical elements. It is widely used in chemistry, physics, and other sciences, and is generally seen as an icon of ch ...
, hydrogen does not, under ordinary conditions, exhibit the properties of an alkali metal. Instead, it forms
diatomic Diatomic molecules () are molecules composed of only two atoms, of the same or different chemical elements. If a diatomic molecule consists of two atoms of the same element, such as hydrogen () or oxygen (), then it is said to be homonuclear. Ot ...
molecules, analogous to
halogens The halogens () are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). In the modern IUPAC nomenclature, this group is ...
and some
nonmetal In chemistry, a nonmetal is a chemical element that generally lacks a predominance of metallic properties; they range from colorless gases (like hydrogen) to shiny solids (like carbon, as graphite). The electrons in nonmetals behave differentl ...
s in the second period of the periodic table, such as
nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
and
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
. Diatomic hydrogen is a gas that, at
atmospheric pressure Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, 7 ...
, liquefies and
solidifies Freezing is a phase transition where a liquid turns into a solid when its temperature is lowered below its freezing point. In accordance with the internationally established definition, freezing means the solidification phase change of a liquid ...
only at very low temperature (20 degrees and 14 degrees above
absolute zero Absolute zero is the lowest limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reach their minimum value, taken as zero kelvin. The fundamental particles of nature have minimum vibration ...
, respectively).
Eugene Wigner Eugene Paul "E. P." Wigner ( hu, Wigner Jenő Pál, ; November 17, 1902 – January 1, 1995) was a Hungarian-American theoretical physicist who also contributed to mathematical physics. He received the Nobel Prize in Physics in 1963 "for his con ...
and
Hillard Bell Huntington Dr. Hillard Bell Huntington (21 December 1910 in Wilkes Barre, Luzerne County, Pennsylvania – 17 July 1992 Troy, Rensselaer County, New York) was a physicist who (together with Eugene Wigner) first proposed, in 1935, that hydrogen could occur in a ...
predicted that under an immense
pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...
of around , hydrogen would display
metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...
lic properties: instead of discrete molecules (which consist of two electrons bound between two protons), a bulk phase would form with a solid lattice of protons and the electrons
delocalized In chemistry, delocalized electrons are electrons in a molecule, ion or solid metal that are not associated with a single atom or a covalent bond.IUPAC Gold Boo''delocalization''/ref> The term delocalization is general and can have slightly dif ...
throughout. Since then, producing metallic hydrogen in the laboratory has been described as "...the holy grail of high-pressure physics." The initial prediction about the amount of pressure needed was eventually shown to be too low. Since the first work by Wigner and Huntington, the more modern theoretical calculations point toward higher but nonetheless potentially achievable metalization pressures of around .


Liquid metallic hydrogen

Helium-4 Helium-4 () is a stable isotope of the element helium. It is by far the more abundant of the two naturally occurring isotopes of helium, making up about 99.99986% of the helium on Earth. Its nucleus is identical to an alpha particle, and consis ...
is a
liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...
at normal pressure near
absolute zero Absolute zero is the lowest limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reach their minimum value, taken as zero kelvin. The fundamental particles of nature have minimum vibration ...
, a consequence of its high
zero-point energy Zero-point energy (ZPE) is the lowest possible energy that a quantum mechanical system may have. Unlike in classical mechanics, quantum systems constantly Quantum fluctuation, fluctuate in their lowest energy state as described by the Heisen ...
(ZPE). The ZPE of protons in a dense state is also high, and a decline in the ordering energy (relative to the ZPE) is expected at high pressures. Arguments have been advanced by
Neil Ashcroft Neil William Ashcroft (27 November 1938 – 15 March 2021) was a British solid-state physicist. Early life and education Ashcroft was born in London on 27 November 1938, and migrated to New Zealand in 1947. He was educated at Hutt Valley High Sc ...
and others that there is a melting point maximum in
compressed hydrogen Compressed hydrogen (CH2, CGH2 or CGH2) is the gaseous state of the element hydrogen kept under pressure. Compressed hydrogen in hydrogen tanks at 350 bar (5,000 psi) and 700 bar (10,000 psi) is used for mobile hydrogen storage in hydrogen vehic ...
, but also that there might be a range of densities, at pressures around 400 GPa, where hydrogen would be a liquid metal, even at low temperatures. Geng predicted that the ZPE of protons indeed lowers the melting temperature of hydrogen to a minimum of at pressures of . Within this flat region there might be an elemental
mesophase In chemistry and chemical physics, a mesophase is a state of matter intermediate between liquid and solid. Gelatin is a common example of a partially ordered structure in a mesophase. Further, biological structures such as the lipid bilayers of cel ...
intermediate between the liquid and solid state, which could be metastably stabilized down to low temperature and enter a supersolid state.


Superconductivity

In 1968,
Neil Ashcroft Neil William Ashcroft (27 November 1938 – 15 March 2021) was a British solid-state physicist. Early life and education Ashcroft was born in London on 27 November 1938, and migrated to New Zealand in 1947. He was educated at Hutt Valley High Sc ...
suggested that metallic hydrogen might be a superconductor, up to
room temperature Colloquially, "room temperature" is a range of air temperatures that most people prefer for indoor settings. It feels comfortable to a person when they are wearing typical indoor clothing. Human comfort can extend beyond this range depending on ...
(). This hypothesis is based on an expected strong
coupling A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end mov ...
between conduction electrons and
lattice vibration In physics, a phonon is a collective excitation in a periodic, elastic arrangement of atoms or molecules in condensed matter, specifically in solids and some liquids. A type of quasiparticle, a phonon is an excited state in the quantum mechanical ...
s. This may have actually been confirmed as of early 2019; metallic hydrogen has been made at least twice in the laboratory, and a 250K
Meissner effect The Meissner effect (or Meissner–Ochsenfeld effect) is the expulsion of a magnetic field from a superconductor during its transition to the superconducting state when it is cooled below the critical temperature. This expulsion will repel a n ...
has been tentatively observed but not independently verified by Silvera et al. and a team in France.


As a rocket propellant

Metastable In chemistry and physics, metastability denotes an intermediate Energy level, energetic state within a dynamical system other than the system's ground state, state of least energy. A ball resting in a hollow on a slope is a simple example of me ...
metallic hydrogen may have potential as a highly efficient rocket propellant, with a theoretical
specific impulse Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine (a rocket using propellant or a jet engine using fuel) creates thrust. For engines whose reaction mass is only the fuel they carry, specific impulse i ...
of up to 1700 seconds (for reference, the current most powerful chemical rocket propellants have an ISP less than 500), although a metastable form suitable for mass-production and conventional high-volume storage may not exist. Another significant issue is the heat of the reaction, which at over 6000 K is too high for any known engine materials to be used. This would necessitate diluting the metallic hydrogen with water or liquid hydrogen, a mixture that would still provide a significant performance boost from current propellants.


Possibility of novel types of quantum fluid

Presently known "super" states of matter are superconductors,
superfluid Superfluidity is the characteristic property of a fluid with zero viscosity which therefore flows without any loss of kinetic energy. When stirred, a superfluid forms vortices that continue to rotate indefinitely. Superfluidity occurs in two ...
liquids and gases, and supersolids.
Egor Babaev Egor Babaev (born 1973) is a Russian-born Swedish physicist. In 2001, he received his PhD in theoretical physics from Uppsala University (Sweden). In 2006 he joined the faculty of the KTH Royal Institute of Technology in Stockholm. In 2007-2013 ...
predicted that if hydrogen and
deuterium Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two Stable isotope ratio, stable isotopes of hydrogen (the other being Hydrogen atom, protium, or hydrogen-1). The atomic nucleus, nucleus of a deuterium ato ...
have liquid metallic states, they might have quantum ordered states that cannot be classified as superconducting or superfluid in the usual sense. Instead, they might represent two possible novel types of
quantum fluid A quantum fluid refers to any system that exhibits quantum mechanical effects at the macroscopic level such as superfluids, superconductors, ultracold atoms, etc. Typically, quantum fluids arise in situations where both quantum mechanical effects an ...
s: ''superconducting superfluids'' and ''metallic superfluids''. Such fluids were predicted to have highly unusual reactions to external magnetic fields and rotations, which might provide a means for experimental verification of Babaev's predictions. It has also been suggested that, under the influence of a magnetic field, hydrogen might exhibit
phase transition In chemistry, thermodynamics, and other related fields, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic states of ...
s from superconductivity to superfluidity and vice versa.


Lithium alloying reduces requisite pressure

In 2009, Zurek ''et al.'' predicted that the
alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...
would be a stable metal at only one quarter of the pressure required to metallize hydrogen, and that similar effects should hold for alloys of type LiH''n'' and possibly "other alkali high-hydride systems", i.e. alloys of type XH''n'' where X is an
alkali metal The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K),The symbols Na and K for sodium and potassium are derived from their Latin names, ''natrium'' and ''kalium''; these are still the origins of the names ...
. This was later verified in AcH8 and LaH10 with Tc approaching 270K leading to speculation that other compounds may even be stable at mere MPa pressures with room temperature superconductivity.


Experimental pursuit


Shock-wave compression, 1996

In March 1996, a group of scientists at
Lawrence Livermore National Laboratory Lawrence Livermore National Laboratory (LLNL) is a federal research facility in Livermore, California, United States. The lab was originally established as the University of California Radiation Laboratory, Livermore Branch in 1952 in response ...
reported that they had
serendipitously Serendipity is an unplanned fortunate discovery. Serendipity is a common occurrence throughout the history of product invention and scientific discovery. Etymology The first noted use of "serendipity" was by Horace Walpole on 28 January 1754. I ...
produced the first identifiably metallic hydrogen for about a
microsecond A microsecond is a unit of time in the International System of Units (SI) equal to one millionth (0.000001 or 10−6 or ) of a second. Its symbol is μs, sometimes simplified to us when Unicode is not available. A microsecond is equal to 1000 n ...
at
temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...
s of thousands of
kelvin The kelvin, symbol K, is the primary unit of temperature in the International System of Units (SI), used alongside its prefixed forms and the degree Celsius. It is named after the Belfast-born and University of Glasgow-based engineer and phys ...
s, pressures of over , and densities of approximately . The team did not expect to produce metallic hydrogen, as it was not using
solid hydrogen Solid hydrogen is the solid state of the element hydrogen, achieved by decreasing the temperature below hydrogen's melting point of . It was collected for the first time by James Dewar in 1899 and published with the title "Sur la solidification de ...
, thought to be necessary, and was working at temperatures above those specified by metallization theory. Previous studies in which solid hydrogen was compressed inside
diamond anvil A diamond anvil cell (DAC) is a high-pressure device used in geology, engineering, and materials science experiments. It enables the compression of a small (sub-millimeter-sized) piece of material to extreme pressures, typically up to around 10 ...
s to pressures of up to , did not confirm detectable metallization. The team had sought simply to measure the less extreme
electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allow ...
changes they expected. The researchers used a 1960s-era
light-gas gun The light-gas gun is an apparatus for physics experiments. It is a highly specialized gun designed to generate extremely high velocities. It is usually used to study high-speed impact phenomena (hypervelocity research), such as the formation of ...
, originally employed in
guided missile In military terminology, a missile is a guided airborne ranged weapon capable of self-propelled flight usually by a jet engine or rocket motor. Missiles are thus also called guided missiles or guided rockets (when a previously unguided rocket ...
studies, to shoot an impactor plate into a sealed container containing a half-millimeter thick sample of
liquid hydrogen Liquid hydrogen (LH2 or LH2) is the liquid state of the element hydrogen. Hydrogen is found naturally in the molecular H2 form. To exist as a liquid, H2 must be cooled below its critical point of 33  K. However, for it to be in a fully li ...
. The liquid hydrogen was in contact with wires leading to a device measuring electrical resistance. The scientists found that, as pressure rose to , the electronic energy
band gap In solid-state physics, a band gap, also called an energy gap, is an energy range in a solid where no electronic states can exist. In graphs of the electronic band structure of solids, the band gap generally refers to the energy difference (in ...
, a measure of
electrical resistance The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares some conceptual parallels ...
, fell to almost zero. The band gap of hydrogen in its uncompressed state is about , making it an insulator but, as the pressure increases significantly, the band gap gradually fell to . Because the
thermal energy The term "thermal energy" is used loosely in various contexts in physics and engineering. It can refer to several different well-defined physical concepts. These include the internal energy or enthalpy of a body of matter and radiation; heat, d ...
of the fluid (the temperature became about due to compression of the sample) was above , the hydrogen might be considered metallic.


Other experimental research, 1996–2004

Many experiments are continuing in the production of metallic hydrogen in laboratory conditions at static compression and low temperature. Arthur Ruoff and Chandrabhas Narayana from
Cornell University Cornell University is a private statutory land-grant research university based in Ithaca, New York. It is a member of the Ivy League. Founded in 1865 by Ezra Cornell and Andrew Dickson White, Cornell was founded with the intention to teach an ...
in 1998, and later Paul Loubeyre and René LeToullec from
Commissariat à l'Énergie Atomique The French Alternative Energies and Atomic Energy Commission or CEA (French language, French: :fr:Commissariat à l'énergie atomique et aux énergies alternatives, Commissariat à l'énergie atomique et aux énergies alternatives), is a French pub ...
,
France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
in 2002, have shown that at pressures close to those at the center of the Earth () and temperatures of , hydrogen is still not a true alkali metal, because of the non-zero band gap. The quest to see metallic hydrogen in laboratory at low temperature and static compression continues. Studies are also ongoing on
deuterium Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two Stable isotope ratio, stable isotopes of hydrogen (the other being Hydrogen atom, protium, or hydrogen-1). The atomic nucleus, nucleus of a deuterium ato ...
. Shahriar Badiei and Leif Holmlid from the
University of Gothenburg The University of Gothenburg ( sv, Göteborgs universitet) is a university in Sweden's second largest city, Gothenburg. Founded in 1891, the university is the third-oldest of the current Swedish universities and with 37,000 students and 6000 st ...
have shown in 2004 that condensed metallic states made of excited hydrogen atoms (
Rydberg matter Rydberg matter is an exotic phase (matter), phase of matter formed by Rydberg atoms; it was predicted around 1980 by É. A. Manykin, M. I. Ozhovan and P. P. Poluéktov. It has been formed from various elements like caesium, potassium, hydrogen and ...
) are effective promoters to metallic hydrogen.


Pulsed laser heating experiment, 2008

The theoretically predicted maximum of the melting curve (the prerequisite for the liquid metallic hydrogen) was discovered by Shanti Deemyad and Isaac F. Silvera by using pulsed laser heating. Hydrogen-rich molecular
silane Silane is an inorganic compound with chemical formula, . It is a colourless, pyrophoric, toxic gas with a sharp, repulsive smell, somewhat similar to that of acetic acid. Silane is of practical interest as a precursor to elemental silicon. Sila ...
() was claimed to be metallized and become
superconducting Superconductivity is a set of physical properties observed in certain materials where Electrical resistance and conductance, electrical resistance vanishes and magnetic field, magnetic flux fields are expelled from the material. Any material e ...
by M.I. Eremets ''et al.''. This claim is disputed, and their results have not been repeated.


Observation of liquid metallic hydrogen, 2011

In 2011 Eremets and Troyan reported observing the liquid metallic state of hydrogen and deuterium at static pressures of . This claim was questioned by other researchers in 2012. It is recently proposed that the hydrogen in stars has an electric conductivity of .


Z machine, 2015

In 2015, scientists at the
Z Pulsed Power Facility The Z Pulsed Power Facility, informally known as the Z machine or Z, is the largest high frequency electromagnetic wave generator in the world and is designed to test materials in conditions of extreme temperature and pressure. It was original ...
announced the creation of metallic
deuterium Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two Stable isotope ratio, stable isotopes of hydrogen (the other being Hydrogen atom, protium, or hydrogen-1). The atomic nucleus, nucleus of a deuterium ato ...
using dense liquid
deuterium Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two Stable isotope ratio, stable isotopes of hydrogen (the other being Hydrogen atom, protium, or hydrogen-1). The atomic nucleus, nucleus of a deuterium ato ...
, an electrical insulator-to-conductor transition associated with an increase in optical reflectivity.


Claimed observation of solid metallic hydrogen, 2016

On 5 October 2016, Ranga Dias and Isaac F. Silvera of
Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...
released claims of experimental evidence that solid metallic hydrogen had been synthesized in the laboratory at a pressure of around using a
diamond anvil cell A diamond anvil cell (DAC) is a high-pressure device used in geology, engineering, and materials science experiments. It enables the compression of a small (sub-millimeter-sized) piece of material to extreme pressures, typically up to around 10 ...
. This manuscript was available in October 2016, and a revised version was subsequently published in the journal ''
Science Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for ...
'' in January 2017. In the preprint version of the paper, Dias and Silvera write: Silvera stated that they did not repeat their experiment, since more tests could damage or destroy their existing sample, but assured the scientific community that more tests are coming. He also stated that the pressure would eventually be released, in order to find out whether the sample was
metastable In chemistry and physics, metastability denotes an intermediate Energy level, energetic state within a dynamical system other than the system's ground state, state of least energy. A ball resting in a hollow on a slope is a simple example of me ...
(i.e., whether it would persist in its metallic state even after the pressure was released). Shortly after the claim was published in ''Science'', ''
Nature Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...
'' news division published an article stating that some other physicists regarded the result with skepticism. Prominent members of the high pressure research community criticized the claimed results, questioning the claimed pressures or the presence of metallic hydrogen at the pressures claimed. In February 2017, it was reported that the sample of claimed metallic hydrogen was lost, after the diamond anvils it was contained between broke. In August 2017, Silvera and Dias issued an erratum to the ''Science'' article, regarding corrected
reflectance The reflectance of the surface of a material is its effectiveness in reflecting radiant energy. It is the fraction of incident electromagnetic power that is reflected at the boundary. Reflectance is a component of the response of the electronic ...
values due to variations between the optical density of stressed natural diamonds and the synthetic diamonds used in their pre-compression
diamond anvil cell A diamond anvil cell (DAC) is a high-pressure device used in geology, engineering, and materials science experiments. It enables the compression of a small (sub-millimeter-sized) piece of material to extreme pressures, typically up to around 10 ...
. In June 2019 a team at the
Commissariat à l'énergie atomique et aux énergies alternatives The French Alternative Energies and Atomic Energy Commission or CEA ( French: Commissariat à l'énergie atomique et aux énergies alternatives), is a French public government-funded research organisation in the areas of energy, defense and securit ...
(French Alternative Energies & Atomic Energy Commission) claimed to have created metallic hydrogen at around 425GPa using a toroidal profile diamond anvil cell produced using electron beam machining.


Experiments on fluid deuterium at the National Ignition Facility, 2018

In August 2018, scientists announced new observations regarding the rapid transformation of fluid
deuterium Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two Stable isotope ratio, stable isotopes of hydrogen (the other being Hydrogen atom, protium, or hydrogen-1). The atomic nucleus, nucleus of a deuterium ato ...
from an insulating to a metallic form below 2000 K. Remarkable agreement is found between the experimental data and the predictions based on Quantum Monte Carlo simulations, which is expected to be the most accurate method to date. This may help researchers better understand giant gas planets, such as Jupiter, Saturn and related
exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...
s, since such planets are thought to contain a lot of liquid metallic hydrogen, which may be responsible for their observed powerful
magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
s.


See also

* Hydride#Interstitial hydrides or metallic hydrides * Hydrogen safety#Cryogenics * ''Juno'' (spacecraft) * Metallization pressure *
Slush hydrogen Slush hydrogen is a combination of liquid hydrogen and solid hydrogen at the triple point with a lower temperature and a higher density than liquid hydrogen. It is commonly formed by repeating a freeze-thaw process. This is most easily done by bring ...
*
Timeline of hydrogen technologies This is a timeline of the history of hydrogen technology. Timeline 16th century * c. 1520 – First recorded observation of hydrogen by Paracelsus through dissolution of metals (iron, zinc, and tin) in sulfuric acid. 17th century * 1625 – Fi ...


References

{{DEFAULTSORT:Metallic Hydrogen Hydrogen Phases of matter Physical chemistry Hydrogen physics
Hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
2016 in science October 2016 events Superfluidity