Stability and hydrogen content of iron hydrides under Earth's interior conditions

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K14572
• 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 (2021-2023); Hiroshima University (2020)
• Principal Investigator: Kakizawa Sho 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 (10846819)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 鉄水素化物 / 高温高圧 / 中性子回折 / 放射光X線回折 / 水素位置

Outline of Final Research Achievements

The presence of iron hydrides in the Earth's interior has been proposed, and it is important to understand the stability and hydrogen content of iron hydrides in order to better understand the water (hydrogen) cycle in the Earth's interior. In this study, neutron diffraction and synchrotron radiation X-ray diffraction experiments under high pressure and high temperature were conducted to clarify the stable phase, hydrogen position, and hydrogen-induced volume expansion coefficient of iron hydrides. As a result, it was found that hydrogen in the hcp phase of iron hydrides is located in the octahedron formed by iron atoms, and that the hydrogen-induced volume expansion coefficient increases with temperature.

Free Research Field

地球内部物質学

Academic Significance and Societal Importance of the Research Achievements

本研究では、高圧力下における鉄水素化物の安定性や水素位置を明らかにした。この成果は、地球内部における水の存在や水素貯蔵合金の研究の基礎データになることが期待される。また、本研究で開発した高温高圧下における中性子回折実験の技術は、地球科学の発展につながると共に高圧力を利用した物質科学や材料科学研究に使用されることで研究が促進されることが期待される。