Alternative Thermodynamic Pathway for Producing Neodymium from Oxide Through Molten Solution Non-Ideality and Hydride Precipitation

Alternative Thermodynamic Pathway for Producing Neodymium from Oxide Through Molten Solution Non-Ideality and Hydride Precipitation | 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 Alternative Thermodynamic Pathway for Producing Neodymium from Oxide Through Molten Solution Non-Ideality and Hydride Precipitation Zhigang Fang, Munro Alley, Pei Sun This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6916106/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 27 Dec, 2025 Read the published version in Communications Materials → Version 1 posted You are reading this latest preprint version Abstract We present a novel sustainable method for producing neodymium (Nd) metal. Environmentally sustainable production of rare-earth elements is critical for enabling green technologies. However, Nd, a key rare-earth element used in high-performance magnets for applications such as electric vehicles and wind turbines, is currently produced via an energy-intensive molten-salt electrolysis process. This process releases direct CO 2 emissions as well as perfluorocarbons, which possess a warming potential thousands of times higher than that of CO 2 . In this article, we report the discovery of a two-step metallothermic pathway for producing Nd metal from Nd oxide (Nd 2 O 3 ) with zero direct emissions. In this approach, magnesium (Mg) reduces Nd 2 O 3 , forming an Mg-Nd alloy containing up to 50% Nd by mass. Magnesiothermic reduction of Nd 2 O 3 has historically been considered unfeasible because the free energy change of the reaction is positive under standard conditions. However, thermodynamic modelling and experiments in this work demonstrate that the free energy of mixing of the molten Mg-Nd alloy overcomes this energy barrier, enabling a thermodynamically unfavorable reaction to become favorable. Hydrogen is then used to precipitate solid Nd hydride (NdH y ) from this alloy, separating the Nd from the alloy and enabling reduction of additional Nd 2 O 3 . This work demonstrates the thermodynamic viability of this pathway and provides a general approach that could inform the design of new metallothermic reduction pathways. Physical sciences/Chemistry/Physical chemistry/Thermodynamics Physical sciences/Chemistry/Green chemistry/Sustainability Full Text Additional Declarations Yes there is potential Competing Interest. A patent application (US20250109460A1) has been filed for the process described in this article. The authors are named inventors on the patent. Supplementary Files DataFile.xlsx Source Data SupplementaryInfoforManuscript.docx Supplementary Info Cite Share Download PDF Status: Published Journal Publication published 27 Dec, 2025 Read the published version in Communications Materials → 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-6916106","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":479142501,"identity":"335ada58-117e-4afc-8475-547b8f0ac03c","order_by":0,"name":"Zhigang Fang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA10lEQVRIiWNgGAWjYFACNgaGCiDFD8TMQMzYQJSWM0BKsoGZVC0GB4jVIt9+LIHhQM0du8038g9+LmCwkd1wgIAWxp60AwwHjj1L3nYjmVl6BkOaMUEtzAzpDcwf2A4nm91IZpDmYTicSFALG//zBoYD/w4nG89IZv7Nw/CfsBYeCaDDDrYdtjOQSGYD2nKAsBYJiWcJBw72HU6QOPPYzJrHINl4JiEt8v1phg8OfDtsz9+e+Pg2T4WdbB8hLSAAUpPYAGYaEKEcBuxJUDsKRsEoGAUjDQAAi+NE+jHYztAAAAAASUVORK5CYII=","orcid":"https://orcid.org/0000-0001-9555-6412","institution":"University of Utah","correspondingAuthor":true,"prefix":"","firstName":"Zhigang","middleName":"","lastName":"Fang","suffix":""},{"id":479142502,"identity":"ac4a1773-be99-4e84-a648-f9d7c4c86679","order_by":1,"name":"Munro Alley","email":"","orcid":"","institution":"University of Utah","correspondingAuthor":false,"prefix":"","firstName":"Munro","middleName":"","lastName":"Alley","suffix":""},{"id":479142503,"identity":"08e3cfb5-3360-4bd2-a853-01407ac900f0","order_by":2,"name":"Pei Sun","email":"","orcid":"https://orcid.org/0000-0002-1686-8037","institution":"University of Utah","correspondingAuthor":false,"prefix":"","firstName":"Pei","middleName":"","lastName":"Sun","suffix":""}],"badges":[],"createdAt":"2025-06-17 15:55:13","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6916106/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6916106/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s43246-025-01041-5","type":"published","date":"2025-12-27T05:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":101391800,"identity":"13921337-0f67-427d-80c1-ad92113b93fd","added_by":"auto","created_at":"2026-01-29 08:37:52","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1774049,"visible":true,"origin":"","legend":"","description":"","filename":"Manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6916106/v1_covered_be6b6e90-78e6-4084-8d52-043b159fb3c2.pdf"},{"id":86830250,"identity":"d564e18f-3b1b-4323-84c8-19ff679fb879","added_by":"auto","created_at":"2025-07-16 05:53:59","extension":"xlsx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":11540,"visible":true,"origin":"","legend":"Source Data","description":"","filename":"DataFile.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-6916106/v1/0ea04de6f17e0ca0cdde57f1.xlsx"},{"id":86831330,"identity":"d5838006-79ae-434d-86d3-d02f29e6fb37","added_by":"auto","created_at":"2025-07-16 06:09:59","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":5005174,"visible":true,"origin":"","legend":"Supplementary Info","description":"","filename":"SupplementaryInfoforManuscript.docx","url":"https://assets-eu.researchsquare.com/files/rs-6916106/v1/f9f7f3069229d877055a862d.docx"}],"financialInterests":"\u003cb\u003eYes\u003c/b\u003e there is potential Competing Interest.\nA patent application (US20250109460A1) has been filed for the process described in this article. The authors are named inventors on the patent.","formattedTitle":"Alternative Thermodynamic Pathway for Producing Neodymium from Oxide Through Molten Solution Non-Ideality and Hydride Precipitation","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-6916106/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6916106/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eWe present a novel sustainable method for producing neodymium (Nd) metal. Environmentally sustainable production of rare-earth elements is critical for enabling green technologies. However, Nd, a key rare-earth element used in high-performance magnets for applications such as electric vehicles and wind turbines, is currently produced via an energy-intensive molten-salt electrolysis process. This process releases direct CO\u003csub\u003e2\u003c/sub\u003e emissions as well as perfluorocarbons, which possess a warming potential thousands of times higher than that of CO\u003csub\u003e2\u003c/sub\u003e. In this article, we report the discovery of a two-step metallothermic pathway for producing Nd metal from Nd oxide (Nd\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e) with zero direct emissions. In this approach, magnesium (Mg) reduces Nd\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e, forming an Mg-Nd alloy containing up to 50% Nd by mass. Magnesiothermic reduction of Nd\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e has historically been considered unfeasible because the free energy change of the reaction is positive under standard conditions. However, thermodynamic modelling and experiments in this work demonstrate that the free energy of mixing of the molten Mg-Nd alloy overcomes this energy barrier, enabling a thermodynamically unfavorable reaction to become favorable. Hydrogen is then used to precipitate solid Nd hydride (NdH\u003csub\u003ey\u003c/sub\u003e) from this alloy, separating the Nd from the alloy and enabling reduction of additional Nd\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e. This work demonstrates the thermodynamic viability of this pathway and provides a general approach that could inform the design of new metallothermic reduction pathways.\u003c/p\u003e","manuscriptTitle":"Alternative Thermodynamic Pathway for Producing Neodymium from Oxide Through Molten Solution Non-Ideality and Hydride Precipitation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-16 05:53:54","doi":"10.21203/rs.3.rs-6916106/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"communications-materials","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"commsmat","sideBox":"Learn more about [Communications Materials](https://www.nature.com/commsmat/)","snPcode":"","submissionUrl":"","title":"Communications Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Communications Series","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"544dbbbc-6023-47a0-96b9-52deb301fae5","owner":[],"postedDate":"July 16th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":50876916,"name":"Physical sciences/Chemistry/Physical chemistry/Thermodynamics"},{"id":50876917,"name":"Physical sciences/Chemistry/Green chemistry/Sustainability"}],"tags":[],"updatedAt":"2026-01-29T08:37:46+00:00","versionOfRecord":{"articleIdentity":"rs-6916106","link":"https://doi.org/10.1038/s43246-025-01041-5","journal":{"identity":"communications-materials","isVorOnly":false,"title":"Communications Materials"},"publishedOn":"2025-12-27 05:00:00","publishedOnDateReadable":"December 27th, 2025"},"versionCreatedAt":"2025-07-16 05:53:54","video":"","vorDoi":"10.1038/s43246-025-01041-5","vorDoiUrl":"https://doi.org/10.1038/s43246-025-01041-5","workflowStages":[]},"version":"v1","identity":"rs-6916106","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6916106","identity":"rs-6916106","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}