@article{95ce6f5d623d46ed8ae4f53f74f49dd3,
title = "In situ X-ray diffraction of silicate liquids and glasses under dynamic and static compression to megabar pressures",
abstract = "Properties of liquid silicates under high-pressure and high-temperature conditions are critical for modeling the dynamics and solidification mechanisms of the magma ocean in the early Earth, as well as for constraining entrainment of melts in the mantle and in the present-day core-mantle boundary. Here we present in situ structural measurements by X-ray diffraction of selected amorphous silicates compressed statically in diamond anvil cells (up to 157 GPa at room temperature) or dynamically by laser-generated shock compression (up to 130 GPa and 6,000 K along the MgSiO3 glass Hugoniot). The X-ray diffraction patterns of silicate glasses and liquids reveal similar characteristics over a wide pressure and temperature range. Beyond the increase in Si coordination observed at 20 GPa, we find no evidence for major structural changes occurring in the silicate melts studied up to pressures and temperatures exceeding Earth's core mantle boundary conditions. This result is supported by molecular dynamics calculations. Our findings reinforce the widely used assumption that the silicate glasses studies are appropriate structural analogs for understanding the atomic arrangement of silicate liquids at these high pressures.",
keywords = "Amorphous silicates, High pressure, Shock compression, Static compression, XFEL diffraction",
author = "Guillaume Morard and Hernandez, {Jean Alexis} and Marco Guarguaglini and Riccardo Bolis and Alessandra Benuzzi-Mounaix and Tommaso Vinci and Guillaume Fiquet and Baron, {Marzena A.} and Shim, {Sang Heon} and Byeongkwan Ko and Gleason, {Arianna E.} and Mao, {Wendy L.} and Roberto Alonso-Mori and Lee, {Hae Ja} and Bob Nagler and Eric Galtier and Dimosthenis Sokaras and Glenzer, {Siegfried H.} and Denis Andrault and Gaston Garbarino and Mohamed Mezouar and Schuster, {Anja K.} and Alessandra Ravasio",
note = "Funding Information: We thank F. Lef?vre, N. Coudurier, and B. Baptiste for their help with target characterization and preparation and B. Guillot for fruitful discussions. G.M., G.F., and M.A.B. acknowledge funding from the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation program (ERC PlanetDive; grant agreement 670787). A.E.G. acknowledges the Los Alamos National Laboratory (LANL) Reines Laboratory Directed Research and Development (LDRD). A.E.G. and W.L.M. acknowledge support from the NSF Geophysics Program (grant EAR0738873). A.K.S. is supported by the Helmholtz Association under grant VH-NG-1141. This research was also supported by the POMPEI program of the Agence National de la Recherche (grant ANR-16-CE31-0008). Dynamic compression experiments were performed at the MEC instrument of LCLS, supported by the US Department of Energy (DOE) Office of Science, Fusion Energy Science under contract SF00515, FWP 100182, and were supported by LCLS, a National User Facility operated by Stanford University on behalf of the US DOE, Office of Basic Energy Sciences. Static compression experiments were performed on ID27 beamline at ESRF. Funding Information: Properties of liquid silicates under high-pressure and high-temperature conditions are critical for modeling the dynamics and solidification mechanisms of the magma ocean in the early Earth, as well as for constraining entrainment of melts in the mantle and in the present-day core–mantle boundary. Here we present in situ structural measurements by X-ray diffraction of selected amorphous silicates compressed statically in diamond anvil cells (up to 157 GPa at room temperature) or dynamically by laser-generated shock compression (up to 130 GPa and 6,000 K along the MgSiO3 glass Hugo-niot). The X-ray diffraction patterns of silicate glasses and liquids reveal similar characteristics over a wide pressure and temperature range. Beyond the increase in Si coordination observed at 20 GPa, we find no evidence for major structural changes occurring in the silicate melts studied up to pressures and temperatures exceeding Earth{\textquoteright}s core mantle boundary conditions. This result is supported by molecular dynamics calculations. Our findings reinforce the widely used assumption that the silicate glasses studies are appropriate structural analogs for understanding the atomic arrangement of silicate liquids at these high pressures. Publisher Copyright: {\textcopyright} 2020 National Academy of Sciences. All rights reserved.",
year = "2020",
month = jun,
day = "2",
doi = "10.1073/pnas.1920470117",
language = "English (US)",
volume = "117",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
publisher = "National Academy of Sciences",
number = "22",
}