162188 20251204145007.0 doi 10.1021/acsanm.5c01929 sideral 144781 ART-2025-144781 eng Nuñez, Jorge M. Phase Stability and Structural Evolution of Core/Shell Iron Oxide Nanoparticles Due to Oxidative Diffusion: Implications for Spintronic Applications 2025 Core/shell iron oxide nanoparticles are promising candidates for spintronic applications due to their tunable magnetic properties and interfacial exchange interactions that allow the modulation of spin-polarized conduction. However, their performance depends critically on phase stability and structural integrity under fabrication and operating conditions involving thermal and oxidative diffusion. This study examines the transformation of iron oxide nanoparticles induced by oxidative diffusion in thermal annealing from wüstite to hematite through an intermediate (wüstite)-core/(magnetite–maghemite)-shell structure. The nanoparticles exhibit a rounded cubic morphology, with a distorted C2/m FeO phase at the core under compressive strain along (010), while the Fe3O4 shell exhibits tensile strain along (110). Oxygen diffusion occurs preferentially along [100] from the cube faces, influencing shape evolution. The system exhibits an exchange bias field of up to 3 kOe and enhanced magnetic hardening of up to 4 kOe, attributed to interfacial exchange interactions. Higher annealing temperature promotes the formation of γ-Fe2O3 with ordered vacancies. The exchange bias effect persists, even when the FeO core is smaller than 1 nm in size, indicating that the strain stabilizes the antiferromagnetic (AFM) order and enhances core/shell magnetic coupling. As oxidation proceeds, strain is gradually relaxed, and at 873 K, the oxidation to hematite is promoted, characterized by a Morin transition at 245 K. These findings reveal the intricate relationship between oxidation-driven structural evolution and magnetic behavior in engineered nanoparticle systems, underscoring the critical importance of material selection tailored to specific fabrication processes, operating conditions, and device performance requirements. info:eu-repo/grantAgreement/ES/DGA/E13-23R info:eu-repo/grantAgreement/EC/H2020/101007629 /EU/Nanomaterials for Enzymatic Control of Oxidative Stress Toxicity and Free Radical Generation/NESTOR This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No H2020 101007629 -NESTOR info:eu-repo/grantAgreement/EC/H2020/101007825/EU/ULtra ThIn MAgneto Thermal sEnsor-Ing/ULTIMATE-I This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No H2020 101007825-ULTIMATE-I info:eu-repo/grantAgreement/EC/H2020/872631 /EU/Memristive and multiferroic materials for emergent logic units in nanoelectronics/MELON This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No H2020 872631 -MELON info:eu-repo/grantAgreement/ES/MICIU/CEX2023-001286-S info:eu-repo/grantAgreement/ES/MICIU/PID2023-151080NB-I00 info:eu-repo/semantics/closedAccess All rights reserved http://www.europeana.eu/rights/rr-f/ info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Lima, Enio Lohr, Javier Hernán Vásquez Mansilla, Marcelo Zysler, Roberto D. Tolley, Alfredo Bartolomé, Fernando (orcid)0000-0002-0047-1772 Rubín, Javier Universidad de Zaragoza (orcid)0000-0003-1029-3751 Hettler, Simón (orcid)0000-0002-9102-7895 Arenal, Raúl (orcid)0000-0002-2071-9093 Aguirre, Myriam Haydee Universidad de Zaragoza (orcid)0000-0002-1296-4793 Winkler, Elin L. 5001 065 Universidad de Zaragoza Dpto. Ciencia Tecnol.Mater.Fl. Área Cienc.Mater. Ingen.Metal. 2003 395 Universidad de Zaragoza Dpto. Física Materia Condensa. Área Física Materia Condensada 8, 25 (2025), 13024-13036 ACS appl. nano mater. ACS APPLIED NANO MATERIALS 2574-0970 4615874 http://zaguan.unizar.es/record/162188/files/texto_completo.pdf Versión publicada 3204965 http://zaguan.unizar.es/record/162188/files/texto_completo.jpg?subformat=icon icon Versión publicada oai:zaguan.unizar.es:162188 articulos driver 2025-12-04-14:45:24 ARTICLE