Density measurements and structure of Fe and Fe-light elements alloy liquid

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K13902
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: Tohoku University
• Principal Investigator: Kamada Seiji 東北大学, 学際科学フロンティア研究所, 助教 (30611793)
• Research Collaborator: TERASAKI Hidenori
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 地球核 / ダイヤモンドアンビルセル / 密度測定 / Ｘ線吸収法 / 非晶質物質 / 放射光

Outline of Final Research Achievements

The Earth core is divided into liquid and solid cores. Densities of the cores were estimated seismologically and they are smaller than those of pure Fe, suggesting light elements exist in the cores. Therefore, it is very important to investigate densities of core materials. However, it is difficult to measure densities of liquid phases. In this study, I have measured densities of crystalline Fe under high pressures based on an X-ray absorption method in order to establish the method. The densities of Fe were obtained based on the X-ray absorption method and XRD. The densities of Fe based on the X-ray absorption method were consistent with those based on XRD. The difference were less than 2%. This suggests that the X-ray absorption method is a strong method to measure densities, especially liquid and amorphous.

Free Research Field

高温高圧地球物質科学

Academic Significance and Societal Importance of the Research Achievements

本研究では、液体鉄合金の密度測定を行なうためにX線吸収法を用いた。これまで本手法での密度測定が完全に確立されていなかったため、結晶性の鉄の密度をXRDとX線吸収法によって求め、手法の比較を行なった。本研究から両手法によって求められた密度は2%以内の差で一致した。本研究の成果によって液体鉄合金の直接密度測定の可能性が開かれ、地球核の密度や組成についてより正確な議論が期待できる。