Parametric Rietveld refinement and magnetic characterization of superparamagnetic iron oxide nanoparticles

[Display omitted] •Superparamagnetic iron oxide nanoparticles for potential biomedical applications.•Effects of thermal treatments on the crystal structure of TEA-SPIONs and OA-SPIONs.•Parametric Rietveld refinements to stablish non-crystallographic model on oxidation. This article describes the syn...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2018-06, Vol.456, p.108-117
Main Authors: Pereira, Guilherme Ferreira Lemos, Costa, Fanny Nascimento, Souza, José Antonio, Haddad, Paula Silvia, Ferreira, Fabio Furlan
Format: Article
Language:English
Subjects:
Antiferromagnetism
Crystal structure
Crystallography
Diffraction
Ferrimagnetism
Hematite
Iron
Iron oxides
Magnetic measurements
Magnetic properties
Magnetism
Magnetite
Nanoparticles
Oleic acid
Oxidation
Parametric Rietveld refinements
Particle size distribution
Phase transitions
Superparamagnetic iron oxide nanoparticles
X ray powder diffraction
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Summary:[Display omitted] •Superparamagnetic iron oxide nanoparticles for potential biomedical applications.•Effects of thermal treatments on the crystal structure of TEA-SPIONs and OA-SPIONs.•Parametric Rietveld refinements to stablish non-crystallographic model on oxidation. This article describes the synthesis of two superparamagnetic iron oxide nanoparticles (SPIONs) covered with different ligands – hydrophobic (oleic acid (OA)) and hydrophilic (tetraethyl ammonium (TEA)) – and the investigation of the effects of thermal treatments on the crystal structure of TEA-SPIONs or OA-SPIONs using X-ray powder diffraction data and parametric Rietveld refinements; we stablished non-crystallographic models to describe how the oxidation processes take place with increasing temperatures for the different systems. The morphological and magnetic properties revealed the nanoparticles have a mean diameter of ∼10 nm in the solid state and are superparamagnetic at room temperature. Magnetization measurements confirmed the superparamagnetic state for both systems and revealed smaller particle sizes and narrower size distribution for OA-SPIONs than for TEA-SPIONs. The thermomagnetic analyses show only the ferrimagnetic phase transition of magnetite for OA-SPIONs while in the TEA-SPIONs, besides the ferrimagnetic phase transition there is the appearance of an antiferromagnetic one disclosing the evolution of hematite phase probably on the surface of magnetite due to thermal cycles.
ISSN:0304-8853
1873-4766
DOI:10.1016/j.jmmm.2018.02.020