High-pressure generation to the lowest mantle condition in multi-anvil apparatus using nano-polycrystalline diamond anvils

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K21901
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 17:Earth and planetary science and related fields
• Research Institution: Ehime University
• Principal Investigator: Kunimoto Takehiro 愛媛大学, 地球深部ダイナミクス研究センター, 特定研究員 (20543169)
• Project Period (FY): 2019-06-28 – 2022-03-31
• Keywords: ダイヤモンド / 降伏強度 / 塑性変形 / 高圧発生 / マルチアンビル装置

Outline of Final Research Achievements

In this study, we developed an experimental technology using nano-polycrystalline diamond to generate pressure condition equivalent to the whole mantle condition of the Earth, and finally achieved high-pressure generation up to 150 GPa, which exceeds the entire the mantle pressure. In the process of developing this technology, observations of the plastic deformation of diamond were conducted with a wide range of temperature and pressure conditions, and the yield strength of diamond between 500- and 1000-degree C was successfully determined by analyzing the width of X-ray diffraction peaks of diamond (100) and (220) collected from various P-T conditions. The yield strength of diamond had previously been measured only at high temperatures of 1000-1500-degree C. In this study, we have succeeded in determining the yield strength of diamond at lower temperature than in previous studies.

Free Research Field

鉱物物理科学

Academic Significance and Societal Importance of the Research Achievements

ダイヤモンドは硬度や熱伝導率などにおいて傑出した物性を持つため、掘削、研磨、加工など現代の工業において、また実験用材料として欠かすことが出来ず、このような利用目的の場合、ダイヤモンドは高い応力環境に曝される。そのため我々は降伏条件を把握した上で利用する必要があるが、ダイヤモンドの高い強度のため明らかにされていなかった。我々はX線その場観察実験により高温高圧条件下におけるダイヤモンド中の応力の蓄積と開放条件を調べ、幅広い温度下における降伏強度を明らかにした。本成果は降伏強度を明らかにするという基礎研究としての成果に加え、工業面でもダイヤモンド材の長寿命化や加工の高速化などに有用である。