Size and property bimodality in magnetic nanoparticle dispersions: single domain particles vs. strongly coupled nanoclusters
Artikel i vetenskaplig tidskrift, 2017

The widespread use of magnetic nanoparticles in the biotechnical sector puts new demands on fast and quantitative characterization techniques for nanoparticle dispersions. In this work, we report the use of asymmetric flow field-flow fractionation (AF4) and ferromagnetic resonance (FMR) to study the properties of a commercial magnetic nanoparticle dispersion. We demonstrate the effectiveness of both techniques when subjected to a dispersion with a bimodal size/magnetic property distribution: i.e., a small superparamagnetic fraction, and a larger blocked fraction of strongly coupled colloidal nanoclusters. We show that the oriented attachment of primary nanocrystals into colloidal nanoclusters drastically alters their static, dynamic, and magnetic resonance properties. Finally, we show how the FMR spectra are influenced by dynamical effects; agglomeration of the superparamagnetic fraction leads to reversible line-broadening; rotational alignment of the suspended nanoclusters results in shape-dependent resonance shifts. The AF4 and FMR measurements described herein are fast and simple, and therefore suitable for quality control procedures in commercial production of magnetic nanoparticles.


E. Wetterskog

Uppsala universitet

A. Castro

Solve Research & Consultancy

Lunjie Zeng

Chalmers, Fysik, Eva Olsson Group

Sarunas Petronis

SP Sveriges Tekniska Forskningsinstitut AB

D. Heinke

Nanopet Pharma

Eva Olsson

Chalmers, Fysik, Eva Olsson Group

L. Nilsson

Lunds universitet

Solve Research & Consultancy

N. Gehrke

Nanopet Pharma

P. Svedlindh

Uppsala universitet


2040-3364 (ISSN) 2040-3372 (eISSN)

Vol. 9 12 4227-4235



Den kondenserade materiens fysik


Chalmers materialanalyslaboratorium



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