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Ikuta D, Ohtani E, Fukui H, Sakamaki T, Heid R, Ishikawa D, Baron AQ. Density deficit of Earth's core revealed by a multimegabar primary pressure scale. Sci Adv 2023; 9:eadh8706. [PMID: 37682990 PMCID: PMC10491286 DOI: 10.1126/sciadv.adh8706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 08/07/2023] [Indexed: 09/10/2023]
Abstract
An accurate pressure scale is a fundamental requirement to understand planetary interiors. Here, we establish a primary pressure scale extending to the multimegabar pressures of Earth's core, by combined measurement of the acoustic velocities and the density from a rhenium sample in a diamond anvil cell using inelastic x-ray scattering and x-ray diffraction. Our scale agrees well with previous primary scales and shock Hugoniots in each experimental pressure range and reveals that previous scales have overestimated laboratory pressures by at least 20% at 230 gigapascals. It suggests that the light element content in Earth's inner core (the density deficit relative to iron) is likely to be double what was previously estimated, or Earth's inner core temperature is much higher than expected, or some combination thereof.
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Affiliation(s)
- Daijo Ikuta
- Department of Earth Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Eiji Ohtani
- Department of Earth Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Hiroshi Fukui
- Materials Dynamics Laboratory, RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198, Japan
| | - Tatsuya Sakamaki
- Department of Earth Science, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Rolf Heid
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, D-76021 Karlsruhe, Germany
| | - Daisuke Ishikawa
- Materials Dynamics Laboratory, RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198, Japan
| | - Alfred Q. R. Baron
- Materials Dynamics Laboratory, RIKEN SPring-8 Center, Sayo, Hyogo 679-5148, Japan
- Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198, Japan
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