{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,23]],"date-time":"2026-08-23T15:22:46Z","timestamp":1787498566282,"version":"build-2736575974"},"reference-count":49,"publisher":"Oxford University Press (OUP)","issue":"11","license":[{"start":{"date-parts":[[2025,9,26]],"date-time":"2025-09-26T00:00:00Z","timestamp":1758844800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["42422201"],"award-info":[{"award-number":["42422201"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["42350002"],"award-info":[{"award-number":["42350002"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Sichuan Science and Technology Program","award":["2023NSFSC1910"],"award-info":[{"award-number":["2023NSFSC1910"]}]},{"name":"Sichuan Science and Technology Program","award":["2024NSFJQ0066"],"award-info":[{"award-number":["2024NSFJQ0066"]}]},{"DOI":"10.13039\/100006296","name":"CAS","doi-asserted-by":"publisher","award":["JCTD-2022-16"],"award-info":[{"award-number":["JCTD-2022-16"]}],"id":[{"id":"10.13039\/100006296","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2025,10,10]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>Seismic observations reveal that Earth\u2019s inner core is rigid yet displays ultralow shear wave velocities (Vs) and an ultra-high Poisson\u2019s ratio (\u223c0.45). While superionic behavior in iron\u2013light element alloys (e.g. carbon) has been proposed to explain these features, experimental validation has been lacking. Here, we combine dynamic high pressure\u2013temperature (P-T) experiments with ab initio molecular dynamics simulations to investigate the elastic properties and atomic behaviors of hexagonal close-packed (hcp) Fe\u20131.5 wt% C (Fe-1.5C) alloy under core-like conditions. Theoretical simulations reveal a temperature-induced transition to a superionic state in the hcp-Fe\u20131.5C alloy above T\/Tm\u00a0\u2248\u00a00.68 (Tm: melting temperature) under high-pressure conditions. This transition provides a physical explanation for both the \u223c23% reduction in Vs relative to pure Fe and the elevated Poisson\u2019s ratio (\u223c0.43) measured for the Fe\u20131.5C alloy at 140 GPa and T\/Tm\u00a0\u2248\u00a00.83 in our shock-wave experiments. Our findings suggest that the inner core may have liquid-like softness arising from both the superionic diffusion of light elements and the atomic collective motion of iron atoms. This work experimentally confirms a previously unrecognized state of matter in the inner core, reconciling long-standing geophysical and seismological discrepancies.<\/jats:p>","DOI":"10.1093\/nsr\/nwaf419","type":"journal-article","created":{"date-parts":[[2025,9,25]],"date-time":"2025-09-25T12:04:54Z","timestamp":1758801894000},"source":"Crossref","is-referenced-by-count":9,"title":["Experimental evidence for superionic Fe\u2013C alloy revealed by shear softening in Earth\u2019s inner core"],"prefix":"10.1093","volume":"12","author":[{"given":"Yuqian","family":"Huang","sequence":"first","affiliation":[{"name":"Institute of Atomic and Molecular Physics, Sichuan University , Chengdu 610065 ,","place":["China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yu","family":"He","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Critical Mineral Research and Exploration, Institute of Geochemistry, Chinese Academy of Sciences , Guiyang 550081 ,","place":["China"]},{"name":"Key Laboratory of High-Temperature and High-Pressure Study of the Earth\u2019s Interior, Institute of Geochemistry, Chinese Academy of Sciences , Guiyang 550081 ,","place":["China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5340-4170","authenticated-orcid":false,"given":"Youjun","family":"Zhang","sequence":"additional","affiliation":[{"name":"Institute of Atomic and Molecular Physics, Sichuan University , Chengdu 610065 ,","place":["China"]},{"name":"State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, Sichuan University , Chengdu 610065 ,","place":["China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jun","family":"Li","sequence":"additional","affiliation":[{"name":"National Key Laboratory for Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics , Mianyang 621900 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