Abstract

Recent discoveries of water-rich Neptune-like exoplanets require a more detailed understanding of the phase diagram of H2O at pressure–temperature conditions relevant to their planetary interiors. The unusual non-dipolar magnetic fields of ice giant planets, produced by convecting liquid ionic water, are influenced by exotic high-pressure states of H2O—yet the structure of ice in this state is challenging to determine experimentally. Here we present X-ray diffraction evidence of a body-centered cubic (BCC) structured H2O ice at 200 GPa and ~ 5000 K, deemed ice XIX, using the X-ray Free Electron Laser of the Linac Coherent Light Source to probe the structure of the oxygen sub-lattice during dynamic compression. Although several cubic or orthorhombic structures have been predicted to be the stable structure at these conditions, we show this BCC ice phase is stable to multi-Mbar pressures and temperatures near the melt boundary. This suggests variable and increased electrical conductivity to greater depths in ice giant planets that may promote the generation of multipolar magnetic fields.

Details

Title
Dynamic compression of water to conditions in ice giant interiors
Author
Gleason, A. E. 1 ; Rittman, D. R. 2 ; Bolme, C. A. 3 ; Galtier, E. 4 ; Lee, H. J. 4 ; Granados, E. 4 ; Ali, S. 5 ; Lazicki, A. 5 ; Swift, D. 5 ; Celliers, P. 5 ; Militzer, B. 6 ; Stanley, S. 7 ; Mao, W. L. 2 

 SLAC National Accelerator Laboratory, Fundamental Physics Directorate, Menlo Park, USA (GRID:grid.445003.6) (ISNI:0000 0001 0725 7771); Stanford University, Geological Sciences, Stanford, USA (GRID:grid.168010.e) (ISNI:0000000419368956) 
 Stanford University, Geological Sciences, Stanford, USA (GRID:grid.168010.e) (ISNI:0000000419368956) 
 Los Alamos National Laboratory, Shock and Detonation Physics, Los Alamos, USA (GRID:grid.148313.c) (ISNI:0000 0004 0428 3079) 
 SLAC National Accelerator Laboratory, Linac Coherent Light Source, Menlo Park, USA (GRID:grid.445003.6) (ISNI:0000 0001 0725 7771) 
 Lawrence Livermore National Laboratory, Shock Physics, Livermore, USA (GRID:grid.250008.f) (ISNI:0000 0001 2160 9702) 
 University of California, Earth and Planetary Science, Berkeley, USA (GRID:grid.47840.3f) (ISNI:0000 0001 2181 7878) 
 Johns Hopkins University, Earth and Planetary Sciences, Baltimore, USA (GRID:grid.21107.35) (ISNI:0000 0001 2171 9311); Johns Hopkins University, Applied Physics Lab, Laurel, USA (GRID:grid.21107.35) (ISNI:0000 0001 2171 9311) 
Publication year
2022
Publication date
2022
Publisher
Nature Publishing Group
e-ISSN
20452322
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2619336414
Copyright
© This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply 2022. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.