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Metallic hydrogen results when hydrogen is sufficiently compressed and undergoes a phase change; it is an example of degenerate matter. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 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 Degenerate matter is matter which has sufficiently high Density that the dominant contribution to its Pressure rises from the Pauli Exclusion Solid metallic hydrogen consists of a crystal lattice of atomic nuclei (namely, protons), with a spacing which is significantly smaller than a Bohr radius. In Mineralogy and Crystallography, a crystal structure is a unique arrangement of Atoms in a Crystal. The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive In the Bohr model of the structure of an Atom, put forward by Niels Bohr in 1913 Electrons orbit a central nucleus. Indeed, the spacing is more comparable with an electron wavelength (see De Broglie wavelength). The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. In Physics, the de Broglie hypothesis (pronounced /brœj/ as French breuil close to "broy" is the statement that all Matter (any object has a Wave The electrons are unbound and behave like the conduction electrons in a metal. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Chemistry, a molecular orbital (or MO) is a region in which an Electron may be found in a Molecule. In Science and engineering, a conductor is a material which contains movable Electric charges. The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across As is the dihydrogen molecule H2, metallic hydrogen is an allotrope. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Allotropy (Gr allos, other and tropos, manner is a behavior exhibited by certain Chemical elements these elements can exist in two or more different In liquid metallic hydrogen protons do not have lattice ordering i. e. the system is a liquid of protons and electrons.

Contents

History

Theoretical Predictions

Metalization of hydrogen under pressure

Though topping the Periodic Table's alkali metal column, hydrogen is not, under ordinary conditions, an alkali metal. The periodic table of the chemical elements is a tabular method of displaying the Chemical elements Although precursors to this table exist its invention is Trends The alkali metals show a number of trends when moving down the group - for instance decreasing electronegativity increasing reactivity and decreasing melting and boiling Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 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. Year 1935 ( MCMXXXV) was a Common year starting on Tuesday (link will display full calendar of the Gregorian calendar. Eugene Paul "EP" Wigner ( Hungarian Wigner Pál Jenő) ( November 17, 1902 &ndash January 1, 1995) was a Professor Hillard Bell Huntington ( 21 Dec 1910 in Wilkes Barre, Luzerne Co Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny [1]. Since then metallic hydrogen was the holy grail of high-pressure physics. The initial prediction about the amount of pressure needed was proven to be too low. [2] Since the first work by Wigner and Huntington the more modern theoretical calculations were pointing toward higher but nonetheless potentially experimentally accessible metalization pressures. Professor Malcolm McMahon (Centre for Science and Extreme Conditions at Edinburgh University) states that they are currently developing techniques for creating pressures of up to five million atmospheres (ie, higher than the pressure at the center of the earth) in hopes of creating metallic hydrogen. The University of Edinburgh (Oilthigh Dhùn Èideann founded in 1582 is a renowned centre for teaching and research in Edinburgh, Scotland, UK. The Standard atmosphere is an international reference pressure defined as 101325 Pa and formerly used as unit of Pressure (symbol atm [3]

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. In Physics, the zero-point energy is the lowest possible Energy that a Quantum mechanical Physical system may possess and is the energy of the 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 400 GPa) where hydrogen may be a liquid metal even at lowest temperatures. [4][5]

Superconductivity

Theory has been put forward by Neil Ashcroft that metallic hydrogen may be a superconductor as high as room temperature (290 K), far higher than any other known candidate material. Superconductivity is a phenomenon occurring in certain Materials generally at very low Temperatures characterized by exactly zero electrical resistance This stems from its extremely high speed of sound and the expected strong coupling between the conduction electrons and the lattice vibrations. Sound is a vibration that travels through an elastic medium as a Wave. In Physics, two systems are coupled if they are interacting with each other Vibration refers to mechanical Oscillations about an equilibrium point. [6]

Possibility of novel types of quantum fluid

Presently known "super" states of matter are superconductors, superfluid liquids and gases, and supersolids. Superconductivity is a phenomenon occurring in certain Materials generally at very low Temperatures characterized by exactly zero electrical resistance Superfluidity is a phase of matter or description of Heat capacity in which unusual effects are observed when Liquids, typically of Helium-4 A supersolid is a spatially ordered material (that is a Solid or Crystal) with Superfluid properties 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]

Experimental pursuit

Metalization of hydrogen in shock-wave compression

In March 1996, 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. A scientist, in the broadest sense refers to any person that engages in a systematic activity to acquire Knowledge or an individual that engages in such practices The Lawrence Livermore National Laboratory ( LLNL) in Livermore California is a scientific research laboratory founded by the University of California in 1952 Serendipity is the effect by which one accidentally discovers something fortunate especially while looking for something else entirely To help compare Orders of magnitude of different Times this page lists times between 10&minus6 seconds and 10&minus5 seconds (1 micro Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic [10]

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. A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. Furthermore, previous studies in which solid hydrogen was compressed inside diamond anvils to pressures of up to 2. A diamond anvil cell (DAC consists of two opposing Diamonds with a sample compressed between the Culets Extreme pressure, which can exceed 1000000 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. Electrical conductivity or specific conductivity is a measure of a material's 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 light gas gun is an apparatus for physics experiments a highly specialized gun designed to generate very high velocities Guided Missile is a London based Independent record label set up by Paul Kearney in 1994. The Millimetre ( American spelling: millimeter, symbol mm) is a unit of Length in the Metric system, equal to Liquid hydrogen (LH2 or LH2 is the Liquid state of the element Hydrogen. The liquid hydrogen was in contact with wires leading to a device capable of measuring electrical resistance.

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. In Solid state physics and related applied fields a band gap, also called an energy gap or bandgap, is an energy range in a solid where no electron states Electrical resistance is a ratio of the degree to which an object opposes an Electric current through it measured in Ohms Its reciprocal quantity is 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. An insulator, also called a Dielectric, is a material that resists the flow of Electric current. 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. Thermal energy is the sum of the sensible energy and latent energy. FLUID ( F ast L ight '''U'''ser '''I'''nterface D esigner is a graphical editor that is used to produce FLTK Source code

Other experimental research since 1996

Many experiments are continuing in the production of metallic hydrogen in laboratory conditions at static compression and low temperature. In scientific inquiry an experiment ( Latin: Ex- periri, "to try out" is a method of investigating particular types of research questions or A laboratory (informally lab) is a facility that provides controlled conditions in which scientific Research, Experiments and Arthur Ruoff and Chandrabhas Narayana from Cornell University in 1998,[11] 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. Year 1998 ( MCMXCVIII) was a Common year starting on Thursday (link will display full 1998 Gregorian calendar) The Commissariat à l’énergie atomique (Atomic Energy Commission or CEA, is a French “public establishment of an industrial and commercial character” whose This article is about the country For a topic outline on this subject see List of basic France topics. See also 2002 (disambiguation Year 2002 ( MMII) was a Common year starting on Tuesday of the Gregorian calendar. The planetary core consists of the innermost layer(s of a Planet. 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. Studies are also undergoing on deuterium. [12]. Shahriar Badiei and Leif Holmlid from the University of Goteborg have shown in 2004 that condensed metallic states made of excited hydrogen atoms (H Rydberg matter) are effective promoters to metallic hydrogen. Rydberg matter is a metastable state of highly excited atoms (see Rydberg atom) which are condensed in a solid- or liquid-like very low density matter [13]

Experimental breakthroughs in 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 innovative technique of pulsed laser heating. [14]

Hydrogen-rich alloy SiH4 was metalized in 2008 and found to be superconducting (by M. Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 I. Eremets et al), confirming earlier theoretical prediction by N. W. Ashcroft. [15] In this hydrogen rich alloy, even at moderate pressures (because of chemical precompression) the hydrogen forms a sublattice with density corresponding to metallic hydrogen.

Metallic hydrogen in other contexts

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. Gravitation is a natural Phenomenon by which objects with Mass attract one another An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312 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. Debt AIDS Trade in Africa (or DATA) is a Multinational non-government organization founded in January 2002 in London by U2 's In Physics, magnetism is one of the Phenomena by which Materials exert attractive or repulsive Forces on other Materials. The Solar System consists of the Sun and those celestial objects bound to it by Gravity.

Applications

Nuclear power

One method of producing nuclear fusion, called inertial confinement fusion, involves aiming laser beams at pellets of hydrogen isotopes. In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus Inertial confinement fusion ( ICF) is a process where Nuclear fusion reactions are initiated by heating and compressing a fuel target typically in the form of A laser is a device that emits Light ( Electromagnetic radiation) through a process called Stimulated emission. Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides The increased understanding of the behavior of hydrogen in extreme conditions could help to increase energy yields.

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. Metastability is a general scientific concept which describes states of delicate equilibrium

In addition, 'MSMH' would make an efficient fuel itself and also a clean one, with only water as an end product. Fuel is any material that is burned or altered in order to obtain energy Water is a common Chemical substance that is essential for the survival of all known forms of Life. 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. A propellant is a material that is used to move ("propel" an object Hydrogen peroxide (H2O2 is a very pale blue liquid which appears colorless in a dilute solution slightly more Viscous than water NASA 's Space Shuttle, officially called the Space Transportation System ( STS) is the Spacecraft currently used by the United States Unfortunately, the 'Lawrence Livermore' experiments produced metallic hydrogen too briefly to determine whether or not metastability is possible. Metastability is a general scientific concept which describes states of delicate equilibrium [16]

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] BBC News Article: Peanut butter diamonds on display (27 June 2007)
  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] 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).
  11. ^ [11] 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).
  12. ^ [12]
  13. ^ S. Badiei, L. Holmlid. Experimental observation of an atomic hydrogen material with H–H bond distance of 150 pm suggesting metallic hydrogen. J. Phys. : Cond. Matter 16 (2004) 7017-7023. [13]
  14. ^ Shanti Deemyad and Isaac F. Silvera The Melting Line of Hydrogen at High Pressures http://arxiv.org/abs/0803.2321
  15. ^ M. I. Eremets, I. A. Trojan, S. A. Medvedev, J. S. Tse, Y. Yao. "Superconductivity in Hydrogen Dominant Materials. " Silane Science 14 March 2008 Vol. 319. no. 5869, pp. 1506–1509
  16. ^ [14] W. J. Nellis Metastable Metallic Hydrogen Glass Lawrence Livermore Preprint (1996).
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