William J. Nellis

Last updated
William J. Nellis
William Nellis.jpg
Born (1941-06-25) June 25, 1941 (age 80)
Chicago, Illinois
Citizenship United States
Known forMaking metallic hydrogen in the fluid state
Awards Bridgman Award of International Association of High Pressure Science and Technology (AIRAPT)
Duvall Award of American Physical Society (APS)
Fellow, Division of Condensed Matter Physics of APS
Edward Teller Fellow (LLNL)
Academic background
EducationBS Physics
PhD Physics
Alma mater Loyola University Chicago
Iowa State University

William J. Nellis (born June 25, 1941) is an American physicist. He is an Associate of the Physics Department of Harvard University. [1] 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. [2]

Contents

Nellis has been President of the International Association for the Advancement of High Pressure Science and Technology (AIRAPT) and Chairman of the American Physical Society (APS) Topical Group on Shock Compression of Condensed Matter. He has received the Bridgman Award of AIRAPT, [3] the Duvall Award of APS [4] and is a Fellow of the APS Division of Condensed Matter Physics. [5]

Nellis is an author or coauthor of more than 250 published papers. Most of his research has been focused on materials during or after dynamic compression at high pressures for properties including electrical conductivities, temperatures, equation-of-state data, and shock-wave profiles to investigate compressibilities and phase transitions in liquids and solids. [6]

Early life and education

Nellis was born in Chicago, Illinois in 1941. He received his B.S. degree in Physics from Loyola University of Chicago, College of Liberal Arts and Sciences, in 1963 and his Ph.D. degree in Physics from Iowa State University in 1968. [1] His Ph.D. thesis research included measurements of electrical and thermal conductivities of single crystals of the Rare Earth elements Gadolinium, Terbium and Holmium in the Ames National Laboratory at Iowa State. [7]

Following graduate school, Nellis was a postdoctoral researcher in the Materials Science Division of Argonne National Laboratory (ANL), where he measured electrical and magnetic properties of ordered and disordered alloys of the Actinide elements Plutonium, Neptunium and Uranium mixed with non-magnetic Transition Metals. The experiments at ISU and ANL were performed at cryogenic temperatures in the range of 2 – 300 Kelvin. [8]

Career and work

From 1970 to 1973, Nellis was Assistant Professor of Physics at Monmouth College (ILL) where he taught undergraduate physics courses and was Director of the College’s Computer Center. In 1973, he left Monmouth to join Lawrence Livermore National Laboratory (LNLL), where he performed computational simulations of condensed matter under dynamic compression driven by shock waves generated with high explosives. [9]

In 1976, Nellis moved within LLNL to the High-Dynamic-Pressure Experimental Group, in which he measured properties of approximately 30 cryogenic liquids and solids compressed dynamically to pressures in the range 20-500 GPa with associated temperatures up to as much as several 1000 Kelvins. [9] Those molecular fluids are representative of fluids in the interiors of Giant Planets and in reacted high explosives. Those temperatures, pressures and densities were generated by impact of a high-velocity projectile onto a target material. Impactors were accelerated with a two-stage light-gas gun to velocities as large as 8 km/s (18,000 mph). Impactors were typically 25 mm in diameter and 2–3 mm thick. Samples were 25 mm in diameter and 0.5 – 3 mm thick. Experimental lifetimes were around 100 nanoseconds. Fast electrical and optical measurements were made with detectors having sub-ns resolution time. [10]

In 2003, Nellis retired from LNLL and joined the Department of Physics at Harvard University as an Associate. Since leaving LLNL, Nellis has collaborated with scientists in Japan, Russia, China and Sweden, as well as in the United States. [1]

Nellis has also been involved with the International Association for the Advancement of High Pressure Science and Technology, AIRAPT, for the greater part of his career serving as the vice president from 1999 to 2003 and as the president from 2003 to 2007. From 1998 to 2007, he served as the editor of the journal Shock Waves. [9]

Significant discoveries

Nellis is most well-known for the first experimental observation of a metallic phase of dense hydrogen, [10] [11] a material predicted to exist by Wigner and Huntington in 1935. [2] Dynamic compression generates temperature T and entropy S on rapid compression and the product TS controls phase stability via the free energy. By tuning the magnitude and temporal shape of a reverberating shock pressure pulse, H2 dissociates to H at sufficiently large density that measured electrical conductivities of fluid H cross over from semiconducting to degenerate metal with Mott’s Minimum Metallic Conductivity at pressure 1.4 million bars (140 GPa), nine-fold H atom density in liquid H2 and calculated temperature of 3000 K. [10] Similar electrical conductivities of H under multiple-shock compression have been measured by Fortov et al. [12] Celliers et al at the NIF pulsed laser [13] have measured optical reflectivity of dense fluid metallic D of ~0.3 under multiple-shock compression, which value agrees with the inception of metallization of D calculated by Rillo et al. [14] Measured electrical conductivities of fluid SiH4 up to 106 GPa under multiple-shock compression with a two-stage light-gas gun [15] are in good agreement with the electrical conductivity data measured in. [10]

Once the pressure dependence of the electrical conductivity of semiconducting and metallic fluid H was measured, those conductivities were used to address the likely cause of the unusual external magnetic fields of the planets Uranus and Neptune, which are neither dipolar nor axisymmetric as the fields of Earth and other planets with magnetic fields. Planetary fields are caused by convection of electrically conducting fluids in their interiors, most of which in Uranus and Neptune is hydrogen. Because the electrical conductivity of fluid H approaches metallic at ~100 GPa, the magnetic fields of Uranus and Neptune are primarily generated close to their outer surfaces, which implies the existence of nondipolar contributions to their fields, [16] as observed. Because Uranus and Neptune are fluids, no strong rotating rock layers exist in their interiors [17] to couple the existence of planetary rotational motion into the convective currents that generate the magnetic fields of Uranus and Neptune. His experiments on liquids expected at high pressures and temperatures in deep planetary interiors have major implications for developing pictures of the interiors of giant planets both in this and in other solar systems. [18]

Through his research, Nellis also discovered that at very high dynamic shock pressures and temperatures, electrons in metals and strong insulators have a common uniform behavior in shock velocity space, [19] which is analogous to Asymptotic Freedom in sub-nuclear High-Energy Physics. [20] [21] The mechanism in insulators is a crossover from strong localized directional electronic bonds to a more-compressible delocalized electronic band structure characteristic of metals. [19]

His technique to recover solids as thin as a micron intact from shock pressures up to a million bars has facilitated synthesis of metastable materials for characterization of material structures and physical properties. [22]

Awards and honors

Selected articles

Related Research Articles

Boron nitride Refractory compound of boron and nitrogen with formula BN

Boron nitride is a thermally and chemically resistant refractory compound of boron and nitrogen with the chemical formula BN. It exists in various crystalline forms that are isoelectronic to a similarly structured carbon lattice. The hexagonal form corresponding to graphite is the most stable and soft among BN polymorphs, and is therefore used as a lubricant and an additive to cosmetic products. The cubic variety analogous to diamond is called c-BN; it is softer than diamond, but its thermal and chemical stability is superior. The rare wurtzite BN modification is similar to lonsdaleite but slightly softer than the cubic form.

Condensed matter physics Branch of physics dealing with a property of matter

Condensed matter physics is the field of physics that deals with the macroscopic and microscopic physical properties of matter, especially the solid and liquid phases which arise from electromagnetic forces between atoms. More generally, the subject deals with "condensed" phases of matter: systems of many constituents with strong interactions between them. More exotic condensed phases include the superconducting phase exhibited by certain materials at low temperature, the ferromagnetic and antiferromagnetic phases of spins on crystal lattices of atoms, and the Bose–Einstein condensate found in ultracold atomic systems. Condensed matter physicists seek to understand the behavior of these phases by experiments to measure various material properties, and by applying the physical laws of quantum mechanics, electromagnetism, statistical mechanics, and other theories to develop mathematical models.

Giant planet Planet much larger than the Earth

The giant planets constitute a diverse type of planet much larger than Earth. They are usually primarily composed of low-boiling-point materials, 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 orbiting other stars.

The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by , , or .

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.

A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another.

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 100–200 gigapascals, although it is possible to achieve pressures up to 770 gigapascals.

Ice giant 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.

Solid oxygen forms at normal atmospheric pressure at a temperature below 54.36 K (−218.79 °C, −361.82 °F). Solid oxygen O2, like liquid oxygen, is a clear substance with a light sky-blue color caused by absorption in the red part of the visible light spectrum.

Molecular solid Solid consisting of discrete molecules

A molecular solid is a solid consisting of discrete molecules. The cohesive forces that bind the molecules together are van der Waals forces, dipole-dipole interactions, quadrupole interactions, π-π interactions, hydrogen bonding, halogen bonding, London dispersion forces, and in some molecular solids, coulombic interactions. Van der Waals, dipole interactions, quadrupole interactions, π-π interactions, hydrogen bonding, and halogen bonding are typically much weaker than the forces holding together other solids: metallic, ionic, and network solids. Intermolecular interactions, typically do not involve delocalized electrons, unlike metallic and certain covalent bonds. Exceptions are charge-transfer complexes such as the tetrathiafulvane-tetracyanoquinodimethane (TTF-TCNQ), a radical ion salt. These differences in the strength of force and electronic characteristics from other types of solids give rise to the unique mechanical, electronic, and thermal properties of molecular solids.

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.

Neptune Planet

Neptune is the eighth and farthest-known Solar planet from the Sun. In the Solar System, it is the fourth-largest planet 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 its near-twin Uranus. Neptune is denser and physically smaller than Uranus because its greater mass causes more gravitational compression of its atmosphere. It is referred to as one of the solar system's two ice giant planets.

The Glossary of fuel cell terms lists the definitions of many terms used within the fuel cell industry. The terms in this fuel cell glossary may be used by fuel cell industry associations, in education material and fuel cell codes and standards to name but a few.

Mineral physics is the science of materials that compose the interior of planets, particularly the Earth. It overlaps with petrophysics, which focuses on whole-rock properties. It provides information that allows interpretation of surface measurements of seismic waves, gravity anomalies, geomagnetic fields and electromagnetic fields in terms of properties in the deep interior of the Earth. This information can be used to provide insights into plate tectonics, mantle convection, the geodynamo and related phenomena.

Samarium monochalcogenides are chemical compounds with the composition SmX, where Sm stands for the lanthanide element samarium and X denotes any one of three chalcogen elements, sulfur, selenium or tellurium, resulting in the compounds SmS, SmSe or SmTe. In these compounds, samarium formally exhibits oxidation state +2, whereas it usually assumes the +3 state, resulting in chalcogenides with the chemical formula Sm2X3.

Superionic water Phase of water that exists at extremely high temperatures and pressures

Superionic water, also called superionic ice or ice XVIII 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. The freely mobile hydrogen ions make superionic water almost as conductive as typical metals, making it a superionic conductor. 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.

Iron–hydrogen alloy

Iron–hydrogen alloy, also known as iron hydride, is an alloy of iron and hydrogen and other elements. Because of its lability when removed from a hydrogen atmosphere, it has no uses as a structural material.

Gas giant Giant planet which mainly consists of light elements such as hydrogen and helium

A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are also called failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. The term “gas giant” was originally synonymous with “giant planet”, but 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.

A polyhydride or superhydride is a compound that contains an abnormally large amount of hydrogen. This can be described as high hydrogen stoichiometry. Examples include iron pentahydride FeH5, LiH6, and LiH7. By contrast, the more well known lithium hydride only has one hydrogen atom.

Metallization pressure is the pressure required for a non-metallic chemical element to become a metal. Every material is predicted to turn into a metal if the pressure is high enough, and temperature low enough.

References

  1. 1 2 3 "William J. Nellis".
  2. 1 2 Wigner, E. and Huntington, H. B. (1935). On the possibility of a metallic modification of hydrogen. Journal of Chemical Physics, 3, 764-770.
  3. ↑ "Bridgman Award recipients".
  4. ↑ "George E. Duvall Shock Compression Science Award".
  5. ↑ "William Nellis".
  6. ↑ "William J. Nellis - Scopus".
  7. ↑ W. J. Nellis and S. Legvold, "Thermal Conductivities and Lorenz Functions of Gadolinium, Terbium, and Holmium Single Crystals," Phys. Rev. 180, 581 (1969)
  8. ↑ W. J. Nellis and M. B. Brodsky, "Magnetism in Palladium-Actinide Alloys," in Plutonium 1970 and Other Actinides, edited by W. N. Miner (Metallurgical Society of the American Institute of Mining, Metallurgical, and Petroleum Engineers, New York, 1970), pp. 346-354.
  9. 1 2 3 "William Joel Nellis, PhD".
  10. 1 2 3 4 Weir, S. T., Mitchell, A. C. and Nellis, W. J. (1996). Metallization of fluid molecular hydrogen at 140 GPa (1.4 Mbar). Physical Review Letters, 76, 1860-1863.
  11. ↑ Nellis, W. J., Weir, S. T. and Mitchell, A. C. (1999). Minimum metallic conductivity of fluid hydrogen at 140 GPa (1.4 Mbar). Physical Review B, 59, 3434-3449.
  12. ↑ Fortov, V. E., Ternovoi, V. A., Zhernokletov, M.V., Mochalov, M. A., Mikhailov, A. L., et al. (2003). Pressure-produced ionization of nonideal plasma in a megabar range of dynamic pressures. Journal of Experimental and Theoretical Physics, 97, 259-278.
  13. ↑ Celliers, P. M., Millot, M., Brygoo, S., McWilliams, R. S., Fratanduono, D. R., Rygg, J. R., et al. (2018). Insulator-metal transition in dense fluid deuterium. Science, 361,677-682.
  14. ↑ Rillo, G., Morales, M. A., Ceperley, D. M. and Pierleoni, C. (2019). Optical properties of high-pressure fluid hydrogen across molecular dissociation. Proceedings of National Academy of Science (U. S.), 116, 9770-9774.
  15. ↑ Zhong, X. F., Liu, F. S., Cai, L. C., Xi, F., Zhang, M. J., Liu, Q. J., Yang, Y. P. and Hao, B. B. (2014). Electrical resistivity of silane multiply shock-compressed to 106 GPa. Chinese Physics Letters, 31, 126201.
  16. ↑ Granzow, K. D. (1983). Spherical harmonic representation of the magnetic field in the presence of a current density. Geophysical Journal of the Royal Astronomical Society, 74, 489-505.
  17. ↑ Helled, R., Anderson, J. D., Podolak, M. and Schubert, G. (2011). Interior models of Uranus and Neptune.Astrophysical Journal, 726, 15-1 – 15-7.
  18. ↑ Nellis, W. J. (2015). The unusual magnetic fields of Uranus and Neptune. Modern Physics Letters B, 29, 1430018-1-1430018-29.
  19. 1 2 Ozaki, N., Nellis, W. J., Mashimo, T., Ramzan, M., Ahuja, R. et al. (2016). Dynamic compression of dense oxide (Gd3Ga5O12) from 0.4 to 2.6 TPa: Universal Hugoniot of fluid metals. Scientific Reports, 6, 26000-1-26000-9.
  20. ↑ Gross, D. J. and Wilczek, F. (1973). Ultraviolet behavior of non-abelian gauge theories. Physical Review Letters, 30, 1343-1346.
  21. ↑ Politzer, H. D. (1973). Reliable Perturbative results for strong interactions. Physical Review Letters, 30, 1346-1349.
  22. ↑ Nellis, W. J. (2017). Metastable ultracondensed hyrogenous materials. Journal of Physics: Condensed Matter, 29, 504001-1-504001-5.
  23. ↑ "APS Fellow Archive". APS. Retrieved 24 September 2020.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.