Japan Geoscience Union Meeting 2018

Presentation information

[EE] Evening Poster

P (Space and Planetary Sciences) » P-PS Planetary Sciences

[P-PS03] Small Bodies in the Solar System: Current Understanding and Future Prospects

Wed. May 23, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Masateru Ishiguro(Department of Physics and Astronomy, Seoul National University), Taishi Nakamoto(Tokyo Institute of Technology), Masahiko Arakawa(神戸大学大学院理学研究科, 共同), Masanao Abe(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency)

[PPS03-P28] Phase relation of MgSO4–H2O system under low temperature and high pressure

*Harada Keita1, Tadashi Kondo1, Miki Shirata1, Takumi Kikegawa2 (1.Department of Earth and Space Science, Graduate School of Science Osaka University, 2.High Energy Accelerator Research Organization)

Keywords:icy body, high pressure, Magnesium sulfate

In order to estimate the internal structure of icy bodies, we investigated phase transition of MgSO4-H2O system under low temperature and high pressure. A diamond anvil cell was used for high-pressure generation. A low-temperature circulating system and a Peltier device were used for temperature control. The experimental temperature and pressure range were from -40 °C to room temperature and ambient pressure to 5 GPa, respectively. We used 0, 5, 10, 15, 17, 20, and 25 wt% MgSO4 aqueous solutions to evaluate the influence of MgSO4 on the phase diagram of pure H2O.
The pressure was calculated using the ruby fluorescence method. Raman spectroscopy and textural change in the sample room under optical microscope were used for phase identification in laboratory experiments.
To confirm the results of phase identification, we also conducted X-ray diffraction experiments of the solid phases of MgSO4-H2O system up to about 5GPa at room temperature, at NE-1A station, PF-AR, KEK. We identified Ices VI and VII, magnesium pentahydrate, MgSO4・5H2O, Mg(HSO4)2 in the samples at high pressure.
Our results were different from previous study by Ohtani and Nakamura(2011), who identified magnesium heptahydrate, MgSO4・7H2O as the high-pressure phase .
We will report the detailed results of both Raman spectroscopy and X-ray diffraction experiments and possible phase diagram of MgSO4-H2O system and their application to the icy bodies.