A Perspective on Hydrogen Near the Liquid–Liquid Phase Transition and Metallization of Fluid H
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2021-08-14 |
| Journal | The Journal of Physical Chemistry Letters |
| Authors | W. J. Nellis |
| Institutions | Harvard University |
| Citations | 2 |
Abstract
Section titled “Abstract”Metallic hydrogen has been a major issue in physical chemistry since its prediction in 1935. Its predicted density implies 100 GPa (10<sup>6</sup> bar = Mbar) pressures <i>P</i> are needed to make metallic H with the Fermi temperature <i>T</i><sub>F</sub> = 220 000 K. Temperatures <i>T</i> can be several 1000 K and still be “very low” with <i>T</i>/<i>T</i><sub>F</sub> ≪ 1. In 1996, metallic fluid H was made under dynamic compression at <i>P</i> = 140 GPa and calculated <i>T</i> ≈ 3000 K generated with a two-stage light-gas gun. Those <i>T</i>‘s place metallic H in the liquid-liquid phase transition region. The purpose of this Perspective is to place the phase curve measured in laser-heated diamond anvil cells in context with those measured electrical conductivities. That phase curve is probably caused by dissociation of H<sub>2</sub> to H starting near 90 GPa/1600 K. Metallic H then forms in a crossover as a semiconductor up to 140 GPa/3000 K. Dynamic quasi-isentropic pressure was tuned to make metallic H by design in those conductivity experiments.