Effect of solvothermal synthesis parameters on the crystallite size and atomic structure of cobalt iron oxide nanoparticles.

Autor:	Aalling-Frederiksen O; University of Copenhagen, Department of Chemistry, Nanoscience Center 2100 Copenhagen Ø Denmark kirsten@chem.ku.dk., Pittkowski RK; University of Copenhagen, Department of Chemistry, Nanoscience Center 2100 Copenhagen Ø Denmark kirsten@chem.ku.dk., Anker AS; University of Copenhagen, Department of Chemistry, Nanoscience Center 2100 Copenhagen Ø Denmark kirsten@chem.ku.dk., Quinson J; University of Copenhagen, Department of Chemistry, Nanoscience Center 2100 Copenhagen Ø Denmark kirsten@chem.ku.dk.; Aarhus University, Department of Biological and Chemical Engineering 8200 Aarhus Denmark., Klemeyer L; University of Hamburg, Institute for Nanostructure and Solid-State Physics, Center for Hybrid Nanostructures Luruper Chausse 149 22761 Hamburg Germany., Frandsen BA; Brighham Young University, Department of Physics and Astronomy Provo Utah 84602 USA., Koziej D; University of Hamburg, Institute for Nanostructure and Solid-State Physics, Center for Hybrid Nanostructures Luruper Chausse 149 22761 Hamburg Germany., Jensen KMØ; University of Copenhagen, Department of Chemistry, Nanoscience Center 2100 Copenhagen Ø Denmark kirsten@chem.ku.dk.
Jazyk:	angličtina
Zdroj:	Nanoscale advances [Nanoscale Adv] 2024 Sep 16. Date of Electronic Publication: 2024 Sep 16.
DOI:	10.1039/d4na00590b
Abstrakt:	We here investigate how the synthesis method affects the crystallite size and atomic structure of cobalt iron oxide nanoparticles. By using a simple solvothermal method, we first synthesized cobalt ferrite nanoparticles of ca. 2 and 7 nm, characterized by Transmission Electron Microscopy (TEM), Small Angle X-ray scattering (SAXS), X-ray and neutron total scattering. The smallest particle size corresponds to only a few spinel unit cells. Nevertheless, Pair Distribution Function (PDF) analysis of X-ray and neutron total scattering data shows that the atomic structure, even in the smallest nanoparticles, is well described by the spinel structure, although with significant disorder and a contraction of the unit cell parameter. These effects can be explained by the surface oxidation of the small nanoparticles, which is confirmed by X-ray near edge absorption spectroscopy (XANES). Neutron total scattering data and PDF analysis reveal a higher degree of inversion in the spinel structure of the smallest nanoparticles. Neutron total scattering data also allow magnetic PDF (mPDF) analysis, which shows that the ferrimagnetic domains correspond to ca. 80% of the crystallite size in the larger particles. A similar but less well-defined magnetic ordering was observed for the smallest nanoparticles. Finally, we used a co-precipitation synthesis method at room temperature to synthesize ferrite nanoparticles similar in size to the smallest crystallites synthesized by the solvothermal method. Structural analysis with PDF demonstrates that the ferrite nanoparticles synthesized via this method exhibit a significantly more defective structure compared to those synthesized via a solvothermal method. Competing Interests: There are no conflicts to declare. (This journal is © The Royal Society of Chemistry.)
Databáze:	MEDLINE
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