Japan Geoscience Union Meeting 2023

Presentation information

[E] Oral

S (Solid Earth Sciences ) » S-IT Science of the Earth's Interior & Techtonophysics

[S-IT17] TRANSPORT PROPERTIES AND PROCESSES IN THE EARTH

Thu. May 25, 2023 10:45 AM - 12:00 PM 301B (International Conference Hall, Makuhari Messe)

convener:Bjorn Mysen(Geophysical Laboratory, Carnegie Inst. Washington), Eiji Ohtani(Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University), Naoko Takahashi(Graduate School of Science, The University of Tokyo), Chairperson:Eiji Ohtani(Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University), Bjorn Mysen(Geophysical Laboratory, Carnegie Inst. Washington)

11:45 AM - 12:00 PM

[SIT17-11] Different structural behavior of MgSiO3 and CaSiO3 glasses at high pressures

*Nozomi Kondo1,2, Yoshio Kono1, Itaru Ohira3, Rostislav Hrubiak4, Koji Ohara5, Kiyofumi Nitta5, Oki Sekizawa5 (1.Geodynamics Research Center, Ehime University, 2.Institute for Planetary Materials, Okayama University, 3.Department of Chemistry, Gakushuin University, 4.High Pressure Collaborative Access Team, X-ray Science Division, Argonne National Laboratory, 5.SPring-8 synchrotron facility, Japan Synchrotron Radiation Research Institute)

Keywords:glass structure, MgSiO3, CaSiO3, pair distribution function, high pressure

Knowledge of the structural behavior of silicate melts and/or glasses at high pressures provide fundamental information in discussing the nature and properties of silicate magmas in the Earth’s interior. The behavior of Si-O structure under high pressure conditions has been widely studied, while the effect of cation atoms on the high-pressure structural behavior of silicate melts or glasses has not been well investigated. In this study, we investigated the structures of MgSiO3 and CaSiO3 glasses up to ~5 GPa by in-situ X-ray pair distribution function measurements, to understand the effect of different cations (Mg2+ and Ca2+) on high pressure structural behavior of silicate glasses. We found that the structural behaviors of MgSiO3 and CaSiO3 glasses are different at high pressures. The structure of MgSiO3 glass changes by shrinking of Si-O-Si angle with increasing pressures, which is consistent with previous studies for SiO2 and MgSiO3 glasses. On the other hand, CaSiO3 glass shows almost no change in Si-Si distance at high pressures, while the intensities of two peaks at ~3.0 Å and ~3.5 Å change with increasing pressure. The structural change in CaSiO3 glass at high pressure is interpreted as the change of the fraction of the edge-shared and corner-shared CaO6-SiO4 structures. The different high-pressure structural behavior obtained in MgSiO3 and CaSiO3 glasses may be structural origin of the difference in the properties such as viscosity of MgSiO3 and CaSiO3 melts at high pressures, implying importance of the different structural behavior due to different cation atoms to discuss the nature and properties of silicate magmas in the Earth’s interior.