Suppression and enhancement of the ferromagnetic response in Fe-doped ZnO nanoparticles by calcination of organic nitrogen, phosphorus, and sulfur compounds

• Published in: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology Vol. 15; no. 12; pp. 1 - 10
• Main Authors: Ortega, D., Hernández-Garrido, J. C., Blanco-Andujar, C., Garitaonandia, J. S.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.12.2013; Springer; Springer Nature B.V
• Subjects: Aerobic conditions; Calcination; Cations; Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Energy loss; Exact sciences and technology; Ferromagnetism; Heat treatment; Inorganic Chemistry; Iron; Iron oxides; Lasers; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Magnetic properties; Magnetic properties and materials; Magnetic properties of nanostructures; Magnetization; Materials Science; Nanocrystalline materials; Nanoparticles; Nanoscale materials and structures: fabrication and characterization; Nanotechnology; Optical Devices; Optics; Organic nitrogen; Organic phosphorus; Photonics; Physical Chemistry; Physics; Research Paper; Small particles and nanoscale materials; Spatial distribution; Studies of specific magnetic materials; Sulfur; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Temperature dependence; Trioctylphosphine oxide; X-ray diffraction; Zinc oxide; Nanoparticles; Zinc oxide; Ferromagnetism; Nanostructure processing; Diluted magnetic oxides; Temperature dependence; Iron oxide; Magnetization; Doping; Ferromagnetic materials; Phosphorus; Iron; XRD; Nanostructures; Low field; Heat treatments; Transmission electron microscopy; Spatial distribution; EEL spectroscopy; Organic molecule; Iron additions; Nanostructured materials; Magnetic properties
• ISSN: 1388-0764; 1572-896X
• DOI: 10.1007/s11051-013-2120-5

The current study reports on the preparation of ~10–13 nm ZnO nanoparticles homogeneously doped with Fe 2+ ions ((Zn 0.97 Fe 0.03 )O) and the manipulation of their ferromagnetic response at room temperature with an appropriate post-processing. The homogeneous spatial distribution of iron is studied at atomic column level through high-resolution transmission electron microscopy, high-angle annular dark field, and electron energy loss spectroscopy. Magnetization isotherms show a ferromagnetic feature within the low field region exhibiting temperature dependence. X-ray diffraction and analytical microscopy measurements are compatible with a homogeneous distribution of Fe 2+ over the ZnO lattice, and discard the formation of iron or iron oxide clusters that could account for the low field ferromagnetic signal. From the temperature dependence of the susceptibility, it is inferred that Fe 2+ cations do not order magnetically. Induced defects upon calcination of different organic molecules over the (Zn 0.97 Fe 0.03 )O nanoparticles in aerobic conditions lead to a significant modification of the magnetic properties, even suppressing the room temperature ferromagnetic signal originally observed. More specifically, when the heat treatment is carried out in the presence of dodecylamine, the original room temperature ferromagnetic signal is canceled, whereas an enhancement on the same ferromagnetic contribution is observed when using trioctylphosphine oxide. No significant differences have been found after calcinating 1-dodecanethiol-doped ZnO nanoparticles.