日本地球惑星科学連合2023年大会

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セッション記号 S (固体地球科学) » S-IT 地球内部科学・地球惑星テクトニクス

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

2023年5月25日(木) 10:45 〜 12:00 301B (幕張メッセ国際会議場)

コンビーナ:Mysen Bjorn(Geophysical Laboratory, Carnegie Inst. Washington)、大谷 栄治(東北大学大学院理学研究科地学専攻)、高橋 菜緒子(東京大学大学院理学系研究科)、座長:大谷 栄治(東北大学大学院理学研究科地学専攻)、Mysen Bjorn(Geophysical Laboratory, Carnegie Inst. Washington)

11:45 〜 12:00

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

*近藤 望1,2河野 義生1大平 格3、Rostislav Hrubiak4、尾原 幸治5、新田 清文5、関沢 央輝5 (1.愛媛大学地球深部ダイナミクス研究センター、2.岡山大学惑星物質研究所、3.学習院大学化学科、4.High Pressure Collaborative Access Team, X-ray Science Division, Argonne National Laboratory、5.SPring-8、高輝度光科学研究センター)

キーワード:ガラス構造、MgSiO3、CaSiO3、動径分布関数、高圧

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.