Magnetic, Structural, and Particle Size Analysis of Single- and Multi-Core Magnetic Nanoparticles

Ludwig, Frank; Kazakova, Olga; Barquín, Luis Fernández; Fornara, Andrea; Trahms, Lutz; Steinhoff, Uwe; Svedlindh, Peter; Wetterskog, Erik; Pankhurst, Quentin A.; Southern, Paul; Morales, Puerto; Hansen, Mikkel Fougt; Frandsen, Cathrine; Olsson, Eva; Gustafsson, Stefan; Gehrke, Nicole; Lüdtke‐Buzug, Kerstin; Grüttner, Cordula; Jonasson, Christian; Johansson, Christer

doi:10.1109/tmag.2014.2321456

Cited by 22 publications

(21 citation statements)

References 6 publications

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“…17 For elongated particles, a field-induced magnetic moment may significantly influence the particle dynamics via shape anisotropy. In the present work, however, where the particles have a nearly spherical shape 20 and where only comparatively weak magnetic fields are applied, this effect is found to be negligible. Further, it is noted that an induced magnetic moment has no effect on the optomagnetic signal unless it influences the orientation of a particle.…”

Section: Distributions Of Parameterscontrasting

confidence: 63%

Characterization of fine particles using optomagnetic measurements

Fock

Jonasson²,

Johansson³

et al. 2017

Phys. Chem. Chem. Phys.

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Section: Distributions Of Parameterscontrasting

confidence: 63%

Characterization of fine particles using optomagnetic measurements

Fock

Jonasson²,

Johansson³

et al. 2017

Phys. Chem. Chem. Phys.

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“…Comprehensive structural and magnetic characterization of colloidal dispersions and freeze‐dried powders has been performed following standardized protocols to facilitate comparison of these structures . This is the first step toward standardization of synthesis and characterization of these nanoparticles, which is an important concern and demand nowadays .…”

Section: Introductionmentioning

confidence: 99%

Colloidal Flower‐Shaped Iron Oxide Nanoparticles: Synthesis Strategies and Coatings

Gavilán

Kowalski²,

Heinke

et al. 2017

Part & Part Syst Charact

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101

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The assembly of magnetic cores into regular structures may notably influence the properties displayed by a magnetic colloid. Here, key synthesis parameters driving the self‐assembly process capable of organizing colloidal magnetic cores into highly regular and reproducible multi‐core nanoparticles are determined. In addition, a self‐consistent picture that explains the collective magnetic properties exhibited by these complex assemblies is achieved through structural, colloidal, and magnetic means. For this purpose, different strategies to obtain flower‐shaped iron oxide assemblies in the size range 25–100 nm are examined. The routes are based on the partial oxidation of Fe(OH)2, polyol‐mediated synthesis or the reduction of iron acetylacetonate. The nanoparticles are functionalized either with dextran, citric acid, or alternatively embedded in polystyrene and their long‐term stability is assessed. The core size is measured, calculated, and modeled using both structural and magnetic means, while the Debye model and multi‐core extended model are used to study interparticle interactions. This is the first step toward standardized protocols of synthesis and characterization of flower‐shaped nanoparticles.

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“…A special class of 3D ensembles of magnetic nanoparticles are particle core aggregates or clusters, also referred to as multi-core nanoparticles [37]. Investigation of such particles has attracted much interest in recent years [38][39][40][41], mainly motivated by their large potential for biomedical applications [42,43].…”

Section: Introductionmentioning

confidence: 99%

Dipolar-coupled moment correlations in clusters of magnetic nanoparticles

et al. 2018

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Here, we resolve the nature of the moment coupling between 10-nm DMSA-coated magnetic nanoparticles. The individual iron oxide cores were composed of > 95 % maghemite and agglomerated to clusters. At room temperature the ensemble behaved as a superparamagnet according to Mössbauer and magnetization measurements, however, with clear signs of dipolar interactions. Analysis of temperature-dependent AC susceptibility data in the superparamagnetic regime indicates a tendency for dipolar coupled anticorrelations of the core moments within the clusters. To resolve the directional correlations between the particle moments we performed polarized small-angle neutron scattering and determined the magnetic spin-flip cross-section of the powder in low magnetic field at 300 K. We extract the underlying magnetic correlation function of the magnetization vector field by an indirect Fourier transform of the cross-section. The correlation function suggests non-stochastic preferential alignment between neighboring moments despite thermal fluctuations, with anticorrelations clearly dominating for next-nearest moments. These tendencies are confirmed by Monte Carlo simulations of such core-clusters.

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Magnetic, Structural, and Particle Size Analysis of Single- and Multi-Core Magnetic Nanoparticles

Cited by 22 publications

References 6 publications

Characterization of fine particles using optomagnetic measurements

Characterization of fine particles using optomagnetic measurements

Colloidal Flower‐Shaped Iron Oxide Nanoparticles: Synthesis Strategies and Coatings

Dipolar-coupled moment correlations in clusters of magnetic nanoparticles

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