Earth’s inner core composition inferred from the equations of state of Fe-Si-C-H alloys

Earth’s inner core composition inferred from the equations of state of Fe-Si-C-H alloys | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Earth’s inner core composition inferred from the equations of state of Fe-Si-C-H alloys Efim Kolesnikov, Xiang Li, Susanne C. Müller, Arno Rohrbach, Stephan Klemme, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8986124/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The Earth’s inner core is primarily composed of iron alloyed with lighter elements, yet their precise concentrations remain uncertain. Understanding the effect of light elements on core properties is crucial for constraining its composition. We conducted synchrotron X-ray diffraction experiments on Fe-Si-C-H alloys compressed up to 128 gigapascal (GPa) to derive their equations of state and extrapolate the density and bulk sound velocity to inner core conditions. Our results, substantiated by metal-silicate partitioning and phase relations constraints, indicate that a hexagonal close-packed iron alloy containing ~3–4 weight % silicon, with up to 0.5 weight % carbon, and 0.4 weight % hydrogen, aligns best with seismic observations . These findings suggest silicon is an essential component of the inner core, while carbon and hydrogen can substitute for each other within limited amounts. This refined compositional model advances understanding of the Earth’s inner core and provides geophysical interpretations of its properties. Earth and environmental sciences/Solid Earth sciences/Mineralogy Earth and environmental sciences/Planetary science/Core processes Full Text Additional Declarations There is NO Competing Interest. Supplementary Files Manuscriptsupplementarysubmission.pdf Earth’s inner core composition inferred from the equations of state of Fe-Si-C-H alloys Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8986124","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":600107066,"identity":"3466e9f5-85ca-4f11-8d7f-8dcc37264454","order_by":0,"name":"Efim Kolesnikov","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0002-2964-2547","institution":"University of Münster","correspondingAuthor":true,"prefix":"","firstName":"Efim","middleName":"","lastName":"Kolesnikov","suffix":""},{"id":600107067,"identity":"ac976da2-3867-4c92-9c94-2c77417024ec","order_by":1,"name":"Xiang Li","email":"","orcid":"https://orcid.org/0000-0003-3259-1784","institution":"European Synchrotron Radiation Facility","correspondingAuthor":false,"prefix":"","firstName":"Xiang","middleName":"","lastName":"Li","suffix":""},{"id":600107068,"identity":"19934227-31a7-4b03-b4f3-485bc86f2a39","order_by":2,"name":"Susanne C. 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