Experimental study of melting and dissociation behavior of methane and ammonia under high pressure and high temperature

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K14815
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 17040:Solid earth sciences-related
• Research Institution: Japan Synchrotron Radiation Research Institute (2021-2022); National Institute for Materials Science (2019-2020)
• Principal Investigator: Kadobayashi Hirokazu 公益財団法人高輝度光科学研究センター, 回折・散乱推進室, テニュアトラック研究員 (10836414)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 天王星・海王星 / 高温高圧力実験 / メタン / ダイヤモンド

Outline of Final Research Achievements

The mantles of Uranus and Neptune are composed mainly of water, methane, and ammonia. Conventional experimental studies have investigated the internal structure of icy planets by examining the high-pressure and high-temperature behavior of these mantle materials. However, these studies have mainly dealt with single-component systems, and there have been very few studies of multi-component systems. In this study, high-pressure and high-temperature experiments were performed in multi-component systems that reproduces the mantle of an ice planet. The results show that the conditions for molecular dissociation and polymerization of methane are significantly affected by the influence of water. In particular, in the C-O-H system, the conditions for the formation of diamond from methane were found to shift about 1400 K lower than in the methane single-component system.

Free Research Field

惑星深部物質学

Academic Significance and Societal Importance of the Research Achievements

本研究課題の実施により得られた成果は、より現実的な氷惑星内部における氷マントル物質の挙動の理解に役立つものであり、氷惑星の内部構造モデルの構築のみならず、氷惑星の特異な磁場の発現原因を探る上でも重要な成果である。