Anomalous Magnetic Properties of Nanoparticles Arising from Defect Structures: Topotaxial Oxidation of Fe1-xO|Fe3-δO4 Core|Shell Nanocubes to Single-Phase Particles
2013 (English)In: ACS Nano, ISSN 1936-0851, Vol. 7, no 8, 7132-7144 p.Article in journal (Refereed) Published
Here we demonstrate that the anomalous magnetic properties of iron oxide nanoparticles are correlated with defects in their interior. We studied the evolution of microstructure and magnetic properties of biphasic core|shell Fe1–xO|Fe3−δO4 nanoparticles synthesized by thermal decomposition during their topotaxial oxidation to single-phase nanoparticles. Geometric phase analysis of high-resolution electron microscopy images reveals a large interfacial strain at the core|shell interface and the development of antiphase boundaries. Dark-field transmission electron microscopy and powder X-ray diffraction concur that, as the oxidation proceeds, the interfacial strain is released as the Fe1–xO core is removed but that the antiphase boundaries remain. The antiphase boundaries result in anomalous magnetic behavior, that is, a reduced saturation magnetization and exchange bias effects in single-phase nanoparticles. Our results indicate that internal defects play an important role in dictating the magnetic properties of iron oxide nanoparticles.
Place, publisher, year, edition, pages
2013. Vol. 7, no 8, 7132-7144 p.
iron oxide, core|shell, nanoparticles, defects, antiphase boundary, electron microscopy, exchange bias
Materials Chemistry Nano Technology Chemical Sciences
Research subject Materials Chemistry
IdentifiersURN: urn:nbn:se:su:diva-93790DOI: 10.1021/nn402487qISI: 000323810600076OAI: oai:DiVA.org:su-93790DiVA: diva2:648776
Swedish Research Council (VR); Knut and Alice Wallenberg (KAW) Foundation 3DEM-NATUR 2013-09-162013-09-162013-10-01Bibliographically approved