Influence of clustering on the magnetic properties and hyperthermia performance of iron oxide nanoparticles: Paper

P. Bender*, Jeppe Fock, M. F. Hansen, K. Bogart, P. Southern, F. Ludwig, F. Wiekhorst, W. Szczerba, L. J. Zeng, D. Heinke, N. Gehrke, M. T. Fernandez Diaz, D. Gonzalez-Alonso, J. Espeso, J. Rodriguez Fernandez, C. Johansson

*Corresponding author for this work

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    Clustering of magnetic nanoparticles can drastically change their collective magnetic properties, which in turn may influence their performance in technological or biomedical applications. Here, we investigate a commercial colloidal dispersion (FeraSpin (TM) R), which contains dense clusters of iron oxide cores (mean size around 9 nm according to neutron diffraction) with varying cluster size (about 18-56 nm according to small angle x-ray diffraction), and its individual size fractions (FeraSpin (TM) XS, S, M, L, XL, XXL). The magnetic properties of the colloids were characterized by isothermal magnetization, as well as frequency-dependent optomagnetic and AC susceptibility measurements. From these measurements we derive the underlying moment and relaxation frequency distributions, respectively. Analysis of the distributions shows that the clustering of the initially superparamagnetic cores leads to remanent magnetic moments within the large clusters. At frequencies below 10(5) rad s(-1), the relaxation of the clusters is dominated by Brownian (rotation) relaxation. At higher frequencies, where Brownian relaxation is inhibited due to viscous friction, the clusters still show an appreciable magnetic relaxation due to internal moment relaxation within the clusters. As a result of the internal moment relaxation, the colloids with the large clusters (FSL, XL, XXL) excel in magnetic hyperthermia experiments.
    Original languageEnglish
    Issue number42
    Pages (from-to)425705
    Number of pages12
    Publication statusPublished - 2018


    • Magnetic nanoparticles
    • Multi-core particles
    • Core-clusters
    • Magnetic hyperthermia
    • Nanoflowers
    • Numerical inversion

    Cite this

    Bender, P., Fock, J., Hansen, M. F., Bogart, K., Southern, P., Ludwig, F., Wiekhorst, F., Szczerba, W., Zeng, L. J., Heinke, D., Gehrke, N., Diaz, M. T. F., Gonzalez-Alonso, D., Espeso, J., Rodriguez Fernandez, J., & Johansson, C. (2018). Influence of clustering on the magnetic properties and hyperthermia performance of iron oxide nanoparticles: Paper. Nanotechnology, 29(42), 425705 .