Hydrogen at extreme pressures (Review Article)

• Published in: Физика низких температур
• Date: 2013
• Main Authors: Goncharov, Alexander F., Howie, Ross T., Gregoryanz, Eugene
• Format: Article
• Language: English
• Published: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2013
• Subjects: 9th International Conference on Cryocrystals and Quantum Crystals
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/118453
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Hydrogen at extreme pressures (Review Article) / Alexander F. Goncharov, Ross T. Howie, Eugene Gregoryanz, Ross T. Howie, Eugene Gregoryanz // Физика низких температур. — 2013. — Т. 39, № 5. — С. 523–530. — Бібліогр.: 94 назв. — англ.

Here we review recent experimental and theoretical studies of hydrogen approaching metallization regime. Ex-perimental techniques have made great advances over the last several years making it possible to reach previously unachievable conditions of pressure and temperature and to probe hydrogen at these conditions. Theoretical me-thods have also greatly improved; exemplified through the prediction of new structural and ordered quantum states. Recently, a new solid phase of hydrogen, phase IV, has been discovered in a high-pressure high-temperature do-main. This phase is quite unusual structurally and chemically as it represents an intermediate state between common molecular and monatomic configurations. Moreover, it shows remarkable fluxional characteristics related to its quantum nature, which makes it unique among the solid phases, even of light elements. However, phase IV shows the presence of a band gap and exhibits distinct phonon and libron characteristic of classical solids. The quantum behavior of hydrogen in the limit of very high pressure remains an open question. Prospects of studying hydrogen at more extreme conditions by static and combined static-dynamic methods are also presented.