Defect Engineering in Nd2Zr2O7 Pyrochlore via Synergistic Doping: DFT Predictions and Experimental Confirmation

Defect Engineering in Nd2Zr2O7 Pyrochlore via Synergistic Doping: DFT Predictions and Experimental Confirmation | 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 Research Article Defect Engineering in Nd 2 Zr 2 O 7 Pyrochlore via Synergistic Doping: DFT Predictions and Experimental Confirmation A Ajayraj, Anjana P Anantharaman This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9536375/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Functional energy materials are gaining importance as next-generation energy materials, including Solid Oxide Fuel Cell (SOFC) electrolytes that can achieve higher ionic conductivity at lower temperatures without sacrificing chemical and thermal stability. Pyrochlore (A 2 B 2 O 7 ) is a versatile functional material with a unique structure that can accommodate a variety of A- and B-site cations, enabling tuning of conductivity by adjusting oxygen vacancy concentration. The selection of dopants at the A- and B-sites is critical and extensive; this work uses DFT calculations to identify suitable cations and compositions for Nd 2 Zr 2 O 7 pyrochlore, thereby optimising defect formation energy (DFE). Based on the DFT calculations, Nd 2 Zr 1.7 Mg 0.3 O 7 (NMgZO) and Nd 2 Zr 1.7 Mo 0.3 O 7 (NMoZO) were found to be the optimised compositions of the B-site dopant, and Nd 1.94 Sm 0.06 Zr 1.7 Mo 0.3 O 7 (NSMoZO) was identified as the optimised co-dopant composition. Further, doped and co-doped pyrochlore samples of NMgZO, NMoZO, and NSMoZO were synthesised using the sol-gel method, characterised by XRD, SEM, EPR, and XPS, and tested for ionic conductivity. The conductivity study correlates with the defect formation energy trend: NSMoZO has the highest conductivity (0.0154 S/cm at 750°C) and the lowest DFE (-5.7422 eV), followed by NMoZO (0.0152 S/cm at 750°C) and NMgZO (0.0135 S/cm at 700°C), and agrees with theoretical calculations. The enhanced conductivity stems from the creation of oxygen vacancies due to aliovalent doping, enhanced vacancy generation, and, by the B-site dopant, enhanced ion transport, as well as stability enhancement by the A-site dopant. The work contributes to setting DFE as a tool in designing the pyrochlore electrolyte, which would benefit from dopant selection. Pyrochlore Dopant Defect formation energy DFT Ionic conductivity Full Text Additional Declarations No competing interests reported. Supplementary Files Supportingdocument02.02.2026.docx GraphicalAbstract.tif Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 19 May, 2026 Reviewers agreed at journal 19 May, 2026 Reviewers agreed at journal 18 May, 2026 Reviewers agreed at journal 18 May, 2026 Reviewers agreed at journal 03 May, 2026 Reviewers agreed at journal 30 Apr, 2026 Reviewers invited by journal 30 Apr, 2026 Editor assigned by journal 30 Apr, 2026 Submission checks completed at journal 30 Apr, 2026 First submitted to journal 27 Apr, 2026 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. 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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-9536375","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":634026791,"identity":"37674f5a-3dfe-4167-98ec-f20a0a1d94fc","order_by":0,"name":"A Ajayraj","email":"","orcid":"","institution":"National Institute of Technology Warangal","correspondingAuthor":false,"prefix":"","firstName":"A","middleName":"","lastName":"Ajayraj","suffix":""},{"id":634026792,"identity":"e6e396bf-24ca-4f6c-abc1-9c3036f6c04b","order_by":1,"name":"Anjana P Anantharaman","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4ElEQVRIiWNgGAWjYHCCBDDJz8DYAOEzE6tFsoGxsYFYLRBgcABuDQHAP7vh4eeCmjvyxreb2x/zMNjJM7DzHsCrReLOgWTpGceeGW67c7CxmYch2bCBmS8BvzU3EhKkedgOM267kdjYnMPAnMDAzGOAV4f8jYTk3zz/DttvngHWUk9Yi8GNhDRp3rbDiRskwFoOE9ZiCNRizdv3LHkG0GGz/xgcN2wjpEXuRk7ybZ5vd2z7Z6Q/+Dijolqen/8Mfi0MDDwJQOIAzJ0MDGwE1AMB+wEkLaNgFIyCUTAKsAAAC/ZFuvRKFxEAAAAASUVORK5CYII=","orcid":"","institution":"National Institute of Technology Warangal","correspondingAuthor":true,"prefix":"","firstName":"Anjana","middleName":"P","lastName":"Anantharaman","suffix":""}],"badges":[],"createdAt":"2026-04-27 04:55:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9536375/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9536375/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108810207,"identity":"1ba7aee9-2695-46d2-ba7b-141f4a89476e","added_by":"auto","created_at":"2026-05-08 15:57:50","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1110261,"visible":true,"origin":"","legend":"","description":"","filename":"Manuscriptversion2.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9536375/v1_covered_f0e9f0ae-9977-42e4-9c87-3b681ff7cfd1.pdf"},{"id":108756643,"identity":"971e2f7e-f3f8-42a0-933e-42b1d786b045","added_by":"auto","created_at":"2026-05-08 05:30:05","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":4865201,"visible":true,"origin":"","legend":"","description":"","filename":"Supportingdocument02.02.2026.docx","url":"https://assets-eu.researchsquare.com/files/rs-9536375/v1/d08aaec555622c375d368ca3.docx"},{"id":108806559,"identity":"908a498f-9670-4d5c-ae69-5fef507d342b","added_by":"auto","created_at":"2026-05-08 15:28:55","extension":"tif","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":628101,"visible":true,"origin":"","legend":"","description":"","filename":"GraphicalAbstract.tif","url":"https://assets-eu.researchsquare.com/files/rs-9536375/v1/530a98a23d885f5d78b26f7b.tif"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eDefect Engineering in Nd\u003csub\u003e2\u003c/sub\u003eZr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e Pyrochlore via Synergistic Doping: DFT Predictions and Experimental Confirmation\u003c/p\u003e","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"ionics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":" Learn more about [Ionics](https://www.springer.com/journal/11581) ","snPcode":"11581","submissionUrl":"https://mc.manuscriptcentral.com/ionics","title":"Ionics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Pyrochlore, Dopant, Defect formation energy, DFT, Ionic conductivity","lastPublishedDoi":"10.21203/rs.3.rs-9536375/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9536375/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eFunctional energy materials are gaining importance as next-generation energy materials, including Solid Oxide Fuel Cell (SOFC) electrolytes that can achieve higher ionic conductivity at lower temperatures without sacrificing chemical and thermal stability. Pyrochlore (A\u003csub\u003e2\u003c/sub\u003eB\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e) is a versatile functional material with a unique structure that can accommodate a variety of A- and B-site cations, enabling tuning of conductivity by adjusting oxygen vacancy concentration. The selection of dopants at the A- and B-sites is critical and extensive; this work uses DFT calculations to identify suitable cations and compositions for Nd\u003csub\u003e2\u003c/sub\u003eZr\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e pyrochlore, thereby optimising defect formation energy (DFE). Based on the DFT calculations, Nd\u003csub\u003e2\u003c/sub\u003eZr\u003csub\u003e1.7\u003c/sub\u003eMg\u003csub\u003e0.3\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e (NMgZO) and Nd\u003csub\u003e2\u003c/sub\u003eZr\u003csub\u003e1.7\u003c/sub\u003eMo\u003csub\u003e0.3\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e (NMoZO) were found to be the optimised compositions of the B-site dopant, and Nd\u003csub\u003e1.94\u003c/sub\u003eSm\u003csub\u003e0.06\u003c/sub\u003eZr\u003csub\u003e1.7\u003c/sub\u003eMo\u003csub\u003e0.3\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e (NSMoZO) was identified as the optimised co-dopant composition. Further, doped and co-doped pyrochlore samples of NMgZO, NMoZO, and NSMoZO were synthesised using the sol-gel method, characterised by XRD, SEM, EPR, and XPS, and tested for ionic conductivity. The conductivity study correlates with the defect formation energy trend: NSMoZO has the highest conductivity (0.0154 S/cm at 750\u0026deg;C) and the lowest DFE (-5.7422 eV), followed by NMoZO (0.0152 S/cm at 750\u0026deg;C) and NMgZO (0.0135 S/cm at 700\u0026deg;C), and agrees with theoretical calculations. The enhanced conductivity stems from the creation of oxygen vacancies due to aliovalent doping, enhanced vacancy generation, and, by the B-site dopant, enhanced ion transport, as well as stability enhancement by the A-site dopant. The work contributes to setting DFE as a tool in designing the pyrochlore electrolyte, which would benefit from dopant selection.\u003c/p\u003e","manuscriptTitle":"Defect Engineering in Nd2Zr2O7 Pyrochlore via Synergistic Doping: DFT Predictions and Experimental Confirmation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-05-08 05:30:01","doi":"10.21203/rs.3.rs-9536375/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"75071325832123607156857764247716358430","date":"2026-05-19T12:42:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"329150933547201546829065973200066830739","date":"2026-05-19T10:55:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"57069822264049863272053422950518429224","date":"2026-05-18T15:16:10+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"194798556974149775838874829164801705155","date":"2026-05-18T05:21:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"314876999649515614390686232821143342649","date":"2026-05-03T04:24:45+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"327348507342627650433562672847660997159","date":"2026-04-30T20:55:09+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-30T20:44:45+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-30T06:44:56+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-30T06:44:22+00:00","index":"","fulltext":""},{"type":"submitted","content":"Ionics","date":"2026-04-27T04:36:19+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"ionics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":" Learn more about [Ionics](https://www.springer.com/journal/11581) ","snPcode":"11581","submissionUrl":"https://mc.manuscriptcentral.com/ionics","title":"Ionics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"9297e743-203e-46e1-96e0-bfc6fdc19657","owner":[],"postedDate":"May 8th, 2026","published":true,"recentEditorialEvents":[{"type":"reviewerAgreed","content":"75071325832123607156857764247716358430","date":"2026-05-19T12:42:24+00:00","index":51,"fulltext":""},{"type":"reviewerAgreed","content":"329150933547201546829065973200066830739","date":"2026-05-19T10:55:42+00:00","index":50,"fulltext":""},{"type":"reviewerAgreed","content":"57069822264049863272053422950518429224","date":"2026-05-18T15:16:10+00:00","index":47,"fulltext":""},{"type":"reviewerAgreed","content":"194798556974149775838874829164801705155","date":"2026-05-18T05:21:31+00:00","index":46,"fulltext":""},{"type":"reviewerAgreed","content":"314876999649515614390686232821143342649","date":"2026-05-03T04:24:45+00:00","index":26,"fulltext":""},{"type":"reviewerAgreed","content":"327348507342627650433562672847660997159","date":"2026-04-30T20:55:09+00:00","index":19,"fulltext":""},{"type":"reviewersInvited","content":"26","date":"2026-04-30T20:44:45+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-30T06:44:56+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-30T06:44:22+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-08T05:30:02+00:00","versionOfRecord":[],"versionCreatedAt":"2026-05-08 05:30:01","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9536375","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9536375","identity":"rs-9536375","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}