Metallic hydrogen results when hydrogen is sufficiently compressed and undergoes a phase change; it is an example of degenerate matter. It consists of a crystal lattice of atomic nuclei (namely, protons), with a spacing which is significantly smaller than a Bohr radius. Indeed, the spacing is more comparable with an electron wavelength (see De Broglie wavelength). The electrons are unbound and behave like the conduction electrons in a metal. General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... In computer science, data compression or source coding is the process of encoding information using fewer bits, or information units, thanks to specific encoding schemes. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... Degenerate matter is matter which has sufficiently high density that the dominant contribution to its pressure arises from the Pauli exclusion principle. ... In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ... For other uses, see Proton (disambiguation). ... In the Bohr model of the structure of an atom, put forward by Niels Bohr in 1913, electrons orbit a central nucleus. ... For other uses, see Electron (disambiguation). ... For other uses, see Wavelength (disambiguation). ... The wavelength is the distance between repeating units of a wave pattern. ... For other uses, see Electron (disambiguation). ... In chemistry, a molecular orbital is a region in which an electron may be found in a molecule. ... In science and engineering, conductors are materials that contain movable charges of electricity. ... This article is about metallic materials. ...

History

Predictions

Though topping the Periodic Table's alkali metal column, hydrogen is not, under ordinary conditions, an alkali metal. In 1935, however, physicists Eugene Wigner and H.B. Huntington predicted that under an immense pressure of two-hundred and fifty thousand atmospheres (~ 25 GPa), hydrogen atoms would display metallic properties, losing hold over their electrons.^[1] The pressures necessary made experimental proof elusive, but their prediction about the amount of pressure needed was proven to be too low.^[2] The Periodic Table redirects here. ... The alkali metals are a series of elements comprising Group 1 (IUPAC style) of the periodic table: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... 1935 (MCMXXXV) was a common year starting on Tuesday (link will display full calendar). ... Eugene Wigner Eugene Paul Wigner (Hungarian Wigner Pál JenÅ‘) (November 17, 1902 – January 1, 1995) was a Hungarian physicist and mathematician who received the Nobel Prize in Physics in 1963 for his contributions to the theory of the atomic nucleus and the elementary particles, particularly through the discovery and... This article is about pressure in the physical sciences. ... Diurnal (daily) rhythm of air pressure in northern Germany (black curve is air pressure) Atmospheric pressure is the pressure at any point in the Earths atmosphere. ... The initials GPA can refer, among other things, to Grade Point Average; see Grade (education) Guinness Peat Aviation General Practice Australia, a private, independent medical accreditation society Greyhound Pets of America This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same... Properties For other meanings of Atom, see Atom (disambiguation). ... In the scientific method, an experiment (Latin: ex- periri, of (or from) trying) is a set of observations performed in the context of solving a particular problem or question, to support or falsify a hypothesis or research concerning phenomena. ...

Discovery

In March of 1996, however, a group of scientists at Lawrence Livermore National Laboratory reported that they had serendipitously produced, for about a microsecond and at temperatures of thousands of kelvin and pressures of over a million atmospheres (>100 GPa), the first identifiably metallic hydrogen.^[3] March is the third month of the year in the Gregorian Calendar and one of seven Gregorian months with the length of 31 days. ... Year 1996 (MCMXCVI) was a leap year starting on Monday (link will display full 1996 Gregorian calendar). ... For a List of scientists, see: List of anthropologists List of astronomers List of biologists List of chemists List of computer scientists List of economists List of engineers List of geologists List of inventors List of mathematicians List of meteorologists List of physicists Scientist pairs List of scientist pairs See... Aerial view of the lab and surrounding area, facing NW. The Lawrence Livermore National Laboratory (LLNL) in Livermore, California is a United States Department of Energy (DOE) national laboratory, managed and operated by Lawrence Livermore National Security, LLC (LLNS), a limited liability consortium comprised of Bechtel National, the University of... Look up Serendipity in Wiktionary, the free dictionary. ... To help compare orders of magnitude of different times this page lists times between 10−6 seconds and 10−5 seconds (1. ... For other uses, see Temperature (disambiguation). ... For other uses, see Kelvin (disambiguation). ...

The Lawrence Livermore team did not expect to produce metallic hydrogen, as they were not using solid hydrogen, thought to be necessary, and were working at temperatures above those specified by metallization theory. Furthermore, previous studies in which solid hydrogen was compressed inside diamond anvils to pressures of up to 2.5 million atmospheres (~253 GPa), did not confirm detectable metallization. The team had sought simply to measure the less extreme electrical conductivity changes which were expected to occur. For the River in the North-East of England, see River Team. ... For other uses, see Solid (disambiguation). ... A diamond anvil, more properly a diamond anvil cell (DAC), is a device used by physicists to exert extreme pressures on a material. ... Various meters Measurement is an observation that reduces an uncertainty expressed as a quantity. ... Electrical conductivity or specific conductivity is a measure of a materials ability to conduct an electric current. ...

The researchers used a 1960s-era light gas gun, originally used in guided missile studies, to shoot an impactor-plate into a sealed container containing a half-millimetre thick sample of liquid hydrogen. The liquid hydrogen was in contact with wires leading to a device capable of measuring electrical resistance. The 1960s decade refers to the years from 1960 to 1969. ... The light gas gun is a highly specialized gun designed to generate very high velocities. ... It has been suggested that this article or section be merged into Missile. ... A millimetre (American spelling: millimeter, symbol mm) is an SI unit of length that is equal to one thousandth of a metre. ... Liquid hydrogen is the liquid state of the element hydrogen. ...

The scientists were surprised to find that, as pressure rose to 1.4 million atmospheres (142 GPa), the electronic energy band gap, a measure of electrical resistance, fell to almost zero. The band-gap of hydrogen in its uncompressed state is about 15 eV, making it an insulator but, as the pressure increases significantly, the band-gap gradually falls to 0.3 eV and because the 0.3 eV is provided by the thermal energy of the fluid (the temperature became about 3000 K due to compression of the sample), the hydrogen may, at this point, effectively be considered metallic. Electricity (from New Latin Ä“lectricus, amberlike) is a general term for a variety of phenomena resulting from the presence and flow of electric charge. ... This article or section does not adequately cite its references or sources. ... Electrical resistance is a measure of the degree to which an electrical component opposes the passage of current. ... Look up zero in Wiktionary, the free dictionary. ... An electronvolt (symbol: eV) is the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt. ... This article or section is in need of attention from an expert on the subject. ... In thermal physics, thermal energy is the energy portion of a system that increases with its temperature. ... A fluid is defined as a substance that continually deforms (flows) under an applied shear stress regardless of the magnitude of the applied stress. ...

Liquid metallic hydrogen

The proton has one fourth the mass of 4He, which at normal conditions is a liquid even at lowest temperatures, a consequence of high zero-point energy. Similarly, zero-point energies of protons in a dense state are also high, and at elevated compressions there is expected to be a decline in the ordering energies from interactions relative to protonic zero-point energies. Arguments have been advanced by N.W. Ashcroft and others that there is a melting point maximum in compressed hydrogen, but also that there may be a range of densities (at pressures around 400GPa) where, hydrogen may be a liquid metal even at lowest temperatures. ^{[4] [5]}

Superconductivity

Theory has been put forward by N.W. Ashcroft that metallic hydrogen may be a superconductor as high as room temperature (290K), far higher than any other known candidate material. This stems from its extremely high speed of sound and the expected strong coupling between the conduction electrons and the lattice vibrations.^[6] A magnet levitating above a high-temperature superconductor, cooled with liquid nitrogen. ... This article does not cite any references or sources. ... Sound is a disturbance of mechanical energy that propagates through matter as a wave. ... In physics, two systems are coupled if they are interacting with each other. ... Vibrations are massage movements carried out using the fingertips and palmar surface of the hands. ...

Novel types of quantum fluid

Presently known "super" states of matter are superconductors, superfluid liquids and gases, and supersolids. It was predicted by Egor Babaev that if hydrogen and deuterium have liquid metallic states, they may have ordered states in quantum domain which cannot be classified as superconducting or superfluid in usual sense but represent two possible novel types of quantum fluids: “superconducting superfluid” and “metallic superfluid”. These were shown to have highly unusual reactions to external magnetic field and rotation which might represent a route for experimental verification of these possible new states of matter. It has also been suggested that under the influence of magnetic field the hydrogen may exhibit phase transitions from superconductivity to superfluidity and vice versa. ^{[7] [8] [9]}

Contemporary research

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 in 1998^[10], and later Paul Loubeyre and René LeToullec from Commissariat à l'Énergie Atomique, France in 2002, have shown that at pressures close to those at the center of the Earth (3.2 to 3.4 million atmospheres or 324 to 345 GPa) and temperatures of 100 K–300 K, 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. In the scientific method, an experiment (Latin: ex- periri, of (or from) trying) is a set of observations performed in the context of solving a particular problem or question, to support or falsify a hypothesis or research concerning phenomena. ... This article does not cite any references or sources. ... Cornell redirects here. ... Year 1998 (MCMXCVIII) was a common year starting on Thursday (link will display full 1998 Gregorian calendar). ... The Commissariat à lÉnergie Atomique or CEA, the Atomic Energy Commisson, in English, is a French public establishment of an industrial and commercial character whose mission is to develop all applications of atomic energy, both civilian and military. ... Also see: 2002 (number). ... The planetary core consists of the innermost layer(s) of a planet. ...

Astrophysics

Metallic hydrogen is thought to be present in tremendous amounts in the gravitationally compressed interiors of Jupiter, Saturn, and some of the newly discovered extrasolar planets. Because previous predictions of the nature of those interiors had taken for granted metallization at a higher pressure than the one at which we now know it to happen, those predictions must now be adjusted. The new data indicates much more metallic hydrogen must exist inside Jupiter than previously thought, that it comes closer to the surface, and that therefore, Jupiter's tremendous magnetic field, the strongest of any planet in the solar system is, in turn, produced closer to the surface. Gravity is a force of attraction that acts between bodies that have mass. ... Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... Atmospheric characteristics Atmospheric pressure 140 kPa Hydrogen >93% Helium >5% Methane 0. ... An extrasolar planet, or exoplanet, is a planet beyond the Solar System. ... For other uses, see Data (disambiguation). ... For other senses of this word, see magnetism (disambiguation). ... This article is about the Solar System. ...

Applications

Nuclear power

One method of producing nuclear fusion, called inertial confinement fusion, involves aiming laser beams at pellets of hydrogen isotopes. The increased understanding of the behavior of hydrogen in extreme conditions could help to increase energy yields. The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Inertial confinement fusion using lasers rapidly progressed in the late 1970s and early 1980s from being able to deliver only a few joules of laser energy (per pulse) to a fusion target to being able to deliver tens of kilojoules to a target. ... For other uses, see Laser (disambiguation). ... For other uses, see Isotope (disambiguation). ...

Fuel

It may be possible to produce substantial quantities of metallic hydrogen for practical purposes. The existence has been theorized of a form called 'Metastable Metallic Hydrogen', (abbreviated MSMH) which would not immediately revert to ordinary hydrogen upon the release of pressure. A metastable system with a weakly stable state (1), an unstable transition state (2) and a strongly stable state (3) Metastability is the ability of a non-equilibrium state to persist for some period of time. ...

In addition, 'MSMH' would make an efficient fuel itself and also a clean one, with only water as an end product. Nine times as dense as standard hydrogen, it would give off considerable energy when reverting to standard hydrogen. Burned more quickly, it could be a propellant with five times the efficiency of liquid H₂/O₂, the current Space Shuttle fuel. Unfortunately, the 'Lawrence Livermore' experiments produced metallic hydrogen too briefly to determine whether or not metastability is possible.^[11] For other uses, see Fuel (disambiguation). ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... A propellant is a material that is used to move an object by applying a motive force. ... This article is about the space vehicle. ... A metastable system with a weakly stable state (1), an unstable transition state (2) and a strongly stable state (3) Metastability is the ability of a non-equilibrium state to persist for some period of time. ...

References

1. ^ [1] E. Wigner and H. B. Huntington, On the Possibility of a Metallic Modification of Hydrogen J. Chem. Phys. 3, 764 (1935).
2. ^ [2] P. Loubeyre, R. LeToullec, D. Hausermann, M. Hanfland, R. J. Hemley, H. K. Mao, and L. W. Finger, X-ray diffraction and equation of state of hydrogen at megabar pressures Nature 383, 702 (1996).
3. ^ [3] S. T. Weir, A. C. Mitchell, and W. J. Nellis, Metallization of Fluid Molecular Hydrogen at 140 GPa (1.4 Mbar) Physical Review Letters 76, 1860 - 1863 (1996).
4. ^ [4]. Ashcroft N.W., The hydrogen liquids, J.Phys. A 12, A129-137 (2000).
5. ^ [5]. Bonev, S.A., Schwegler, E., Ogitsu, T., and Galli, G., A quantum fluid of metallic hydrogen suggested by first principles calculations Nature 431, 669 (2004).
6. ^ [6]. N. W. Ashcroft Metallic Hydrogen: A High-Temperature Superconductor? Physical Review Letters 21 1748 - 1749 (1968).
7. ^ [7]. Egor Babaev, N.W. Ashcroft "Violation of the London law and Onsager–Feynman quantization in multicomponent superconductors".
8. ^ [8]. Egor Babaev, A. Sudbo, N.W. Ashcroft "A superconductor to superfluid phase transition in liquid metallic hydrogen" Nature 431 (2004) 666-668.
9. ^ [9]. Egor Babaev, "Vortices with fractional flux in two-gap superconductors and in extended Faddeev model" Phys.Rev.Lett. 89 (2002) 067001.
10. ^ [10] C. Narayana, H. Luo, J. Orloff, and A. L. Ruoff Solid hydrogen at 342 GPa: no evidence for an alkali metal Nature 393, 46-49 (1998).
11. ^ [11] W. J. Nellis Metastable Metallic Hydrogen Glass Lawrence Livermore Preprint (1996).