First principles insights into the structural, thermoelectric and optical behaviour of Bi-based half Heusler alloys RhNbBi and IrNbBi

First principles insights into the structural, thermoelectric and optical behaviour of Bi-based half Heusler alloys RhNbBi and IrNbBi | 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 First principles insights into the structural, thermoelectric and optical behaviour of Bi-based half Heusler alloys RhNbBi and IrNbBi Surendra Singh Sengar, Dinesh C. Gupta This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7935016/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 urgent demand for sustainable energy conversion technologies has stimulated intensive research on thermoelectric materials capable of directly converting waste heat into electricity. In this work, the Bi-based half-Heusler alloys RhNbBi and IrNbBi are investigated through density functional theory to elucidate the interplay between their structural, electronic, mechanical, phonon, thermoelectric, thermodynamic and optical properties relevant to semiconductor and energy applications. Structural optimization and elastic analyses performed using WIEN2k and Quantum ESPRESSO confirm dynamically and mechanically stable non-magnetic metallic ground states with strong 4d/5d-6p hybridization and ductile behaviour satisfying the Born-Huang criteria. Phonon dispersions free from imaginary frequencies verify dynamical stability, while quasi-harmonic Debye modeling reveals excellent thermal robustness up to 1200 K with smoothly varying heat capacity and entropy. The optical spectra, derived from the complex dielectric function, exhibit large static dielectric constants ε₁(0) =70 for RhNbBi and 90 for IrNbBi, high refractive indices n(0) ≈ 7.8–9.0, and strong absorption extending to 12 eV, consistent with experimentally reported optical data for CoTiSb and YbPtBi analogues, thereby validating the present theoretical predictions and establishing their reliability for Bi-based half-Heusler systems. Transport coefficients, evaluated using BoltzTraP2, indicate positive Seebeck coefficients and p-type conduction, suggesting their potential for thermoelectric energy conversion at elevated temperatures. Overall, this study provides comprehensive first-principles insights into Bi-based 4d/5d half-Heusler frameworks, establishing RhNbBi and IrNbBi as promising thermally robust, optically active and mechanically stable candidates for next-generation thermoelectric and optoelectronic devices. Physical sciences/Materials science Physical sciences/Physics Half-Heusler alloys Density functional theory Phonon stability Thermodynamic stability Thermoelectric transport Optoelectronic materials Sustainable energy materials Full Text Additional Declarations No competing interests reported. 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-7935016","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":536613760,"identity":"c9921af9-6252-4154-9e96-1ed53b47f3f8","order_by":0,"name":"Surendra Singh Sengar","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABCElEQVRIiWNgGAWjYDADAyA+wMBgA6QYGw+QoiUNpKWBeC1AcBhM4tUi3957+MXPPQx55hLpDw/8+HPebm37YaAtNTbROA0/cy7NsucZQ7HljByDg71tt5O3nUkEajmWltuAS4tEjpkBzwGGxA03chgOMzbcTjY7ANTC2HAYpxb5+W/MDP+AtaQ/OMzw51yy2fmH+LUw3OAxfgyxJcHgMAPbATuzGwRsMTiTY8Ysc0Ci2ODMG5BfkhPMbgBtScDjF/n2M8Yf3xywyTM4nv74w48/dvZm59MfPvhQY4PbYQwMbBIMDBIJDAIJYF4iWGUCbuUgwPwBrIb/AJhnj1/xKBgFo2AUjEQAAMffbGt+VtOeAAAAAElFTkSuQmCC","orcid":"","institution":"Jiwaji University","correspondingAuthor":true,"prefix":"","firstName":"Surendra","middleName":"Singh","lastName":"Sengar","suffix":""},{"id":536613761,"identity":"9e5e3327-7089-43ae-a58d-201f68df6a0f","order_by":1,"name":"Dinesh C. 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IrNbBi","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Half-Heusler alloys, Density functional theory, Phonon stability, Thermodynamic stability, Thermoelectric transport, Optoelectronic materials, Sustainable energy materials","lastPublishedDoi":"10.21203/rs.3.rs-7935016/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7935016/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe urgent demand for sustainable energy conversion technologies has stimulated intensive research on thermoelectric materials capable of directly converting waste heat into electricity. In this work, the Bi-based half-Heusler alloys RhNbBi and IrNbBi are investigated through density functional theory to elucidate the interplay between their structural, electronic, mechanical, phonon, thermoelectric, thermodynamic and optical properties relevant to semiconductor and energy applications. Structural optimization and elastic analyses performed using WIEN2k and Quantum ESPRESSO confirm dynamically and mechanically stable non-magnetic metallic ground states with strong 4d/5d-6p hybridization and ductile behaviour satisfying the Born-Huang criteria. Phonon dispersions free from imaginary frequencies verify dynamical stability, while quasi-harmonic Debye modeling reveals excellent thermal robustness up to 1200 K with smoothly varying heat capacity and entropy.\u003cbr\u003e\nThe optical spectra, derived from the complex dielectric function, exhibit large static dielectric constants ε₁(0) =70 for RhNbBi and 90 for IrNbBi, high refractive indices n(0) ≈ 7.8–9.0, and strong absorption extending to 12 eV, consistent with experimentally reported optical data for CoTiSb and YbPtBi analogues, thereby validating the present theoretical predictions and establishing their reliability for Bi-based half-Heusler systems. Transport coefficients, evaluated using BoltzTraP2, indicate positive Seebeck coefficients and p-type conduction, suggesting their potential for thermoelectric energy conversion at elevated temperatures. Overall, this study provides comprehensive first-principles insights into Bi-based 4d/5d half-Heusler frameworks, establishing RhNbBi and IrNbBi as promising thermally robust, optically active and mechanically stable candidates for next-generation thermoelectric and optoelectronic devices.\u003c/p\u003e","manuscriptTitle":"First principles insights into the structural, thermoelectric and optical behaviour of Bi-based half Heusler alloys RhNbBi and IrNbBi","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-07 04:14:52","doi":"10.21203/rs.3.rs-7935016/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"82603266-7cbb-41dd-896b-157d495ade72","owner":[],"postedDate":"November 7th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":57057451,"name":"Physical sciences/Materials science"},{"id":57057452,"name":"Physical sciences/Physics"}],"tags":[],"updatedAt":"2025-12-10T12:40:03+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-07 04:14:52","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7935016","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7935016","identity":"rs-7935016","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}