Mapping the Reaction Landscapes of Molten-Salt Fluxes

Mapping the Reaction Landscapes of Molten-Salt Fluxes | 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 Mapping the Reaction Landscapes of Molten-Salt Fluxes Gregory Bassen, Rebecca Han, Thomas Whoriskey, Allana Iwanicki, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9261172/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract The rational synthesis of quantum materials remains a central challenge for the realization of emerging technologies. Molten-salt fluxes are a common technique for synthesizing inorganic materials, granting access to phases that conventional solid-state methods often cannot produce. However, the chemistry by which fluxes influence phase formation remains poorly understood, so flux selection is guided more by precedent than by rational design. Here we introduce a general strategy for probing molten-salt flux chemistry, using the redox-sensitive Ruddlesden–Popper lanthanum nickelate homologous series as a chemical indicator of oxygen fugacity and flux reactivity. By constructing quantitative phase maps of homology formation, we reveal the systematic differences in oxidizing power across alkali halide fluxes and uncover how reaction pathways evolve across high-dimensional reaction landscapes. We discover that sodium iodide is uniquely oxidizing under ambient oxygen pressure, stabilizing LaNiO₃ over a broad temperature window. The formation of Sr₂NaIO₆ in NaI, in which iodine goes from -1 to +7 oxidation states, further indicates that the dissolution of oxygen drives the increased oxygen fugacity. This finding establishes redox-active ions as a design parameter for tuning the chemical potential of fluxes. We thus propose a mechanistic hypothesis for oxygen uptake in molten NaI and suggest that arrow-pushing formalism, a cornerstone of organic chemistry, offers a productive framework for describing reactivity in high-temperature molten-salt synthesis. More broadly, this work establishes chemical indicators as a tool for mapping the reaction landscapes of molten-salt fluxes, laying the groundwork for predictive control over high-dimensional, path-dependent synthesis spaces. Physical sciences/Chemistry/Inorganic chemistry/Solid-state chemistry Physical sciences/Chemistry/Materials chemistry/Superconductors Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SINatureChemistry.pdf SI to Mapping the Reaction Landscapes of Molten-Salt Fluxes Cite Share Download PDF Status: Under Review 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-9261172","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":622219697,"identity":"72b09bd5-4993-4d3d-9985-d03cb971912b","order_by":0,"name":"Gregory 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The formation of Sr₂NaIO₆ in NaI, in which iodine goes from -1 to +7 oxidation states, further indicates that the dissolution of oxygen drives the increased oxygen fugacity. This finding establishes redox-active ions as a design parameter for tuning the chemical potential of fluxes. We thus propose a mechanistic hypothesis for oxygen uptake in molten NaI and suggest that arrow-pushing formalism, a cornerstone of organic chemistry, offers a productive framework for describing reactivity in high-temperature molten-salt synthesis. 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