[S-IT21] Planetary cores: Structure, formation, and evolution

[SIT21-P03] Test of density measurement using X-ray absorption method combined laser-heated diamond anvil cell

*Ryo Tsuruoka¹, Hidenori Terasaki², Hiroyuki Kamina², Seiji Kamada^3,4, Tadashi Kondo¹, Akira Yoneda¹, Naohisa Hirao⁵, Saori Kawaguchi⁵ (1.Department of Earth and Space Science, Graduate School of Science Osaka University, 2.Department of Earth Sciences, Graduate School of Science and Technology, Okayama University, 3.Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 4.AD Science Inc., 5.JASRI)

Keywords:X-ray absorption method, density, laser-heated diamond anvil cell

Density measurement of liquid iron alloy is important to understand the planetary liquid core.
The X-ray absorption method is an effective method because it can directly determine the liquid density. We have been developing the X-ray absorption method combined with a laser-heated diamond anvil cell (DAC), and performed test measurements using Fe₃C as a solid sample.

In X-ray absorption method, density of sample was obtained from measured incident and transmitted X-ray intensities of the samples using Lambert-Beer law. Fe₃C sample and reference material (Ni) were loaded into each hole drilled on a pre-indented Re gasket. Al₂O₃ single crystal was used as pressure medium. High pressure was generated using a symmetric cell with a lever-arm frame. High temperature was generated using laser heating system. X-ray absorption measurements were conducted with monochromatic X-ray of 30 keV at BL10XU beamline in Spring-8.

The X-ray intensities of samples were measured up to 10 GPa and 1700 K. The ratio of incident and transmitted X-ray changes 0.3% from 300 K to 1700 K. The thickness of the sample was determined as 10um from X-ray intensities after quench.