Relating Magnetic Properties and High Hyperthermia Performance of Iron Oxide Nanoflowers
Artikel i vetenskaplig tidskrift, 2018
We investigated, in depth, the interrelations among structure, magnetic properties, relaxation dynamics and magnetic hyperthermia performance of magnetic nanoflowers. The nanoflowers are about 39 nm in size, and consist of densely packed iron oxide cores. They display a remanent magnetization, which we explain by the exchange coupling between the cores, but we observe indications for internal spin disorder. By polarized small-angle neutron scattering, we unambiguously confirm that, on average, the nanoflowers are preferentially magnetized along one direction. The extracted discrete relaxation time distribution of the colloidally dispersed particles indicates the presence of three distinct relaxation contributions. We can explain the two slower processes by Brownian and classical Néel relaxation, respectively. The additionally observed very fast relaxation contributions are attributed by us to the relaxation of disordered spins within the nanoflowers. Finally, we show that the intrinsic loss power (ILP, magnetic hyperthermia performance) of the nanoflowers measured in colloidal dispersion at high frequency is comparatively large and independent of the viscosity of the surrounding medium. This concurs with our assumption that the observed relaxation in the high frequency range is primarily a result of internal spin relaxation, and possibly connected to the disordered spins within the individual nanoflowers.
Författare
P. Bender
Universidad de Cantabria
J. Fock
Danmarks Tekniske Universitet (DTU)
C. Frandsen
Danmarks Tekniske Universitet (DTU)
M. F. Hansen
Danmarks Tekniske Universitet (DTU)
Christoph Balceris
Technische Universität Braunschweig
Frank Ludwig
Technische Universität Braunschweig
Oliver Posth
Physikalisch-Technische Bundesanstalt (PTB)
E. Wetterskog
Uppsala universitet
Lara K. Bogart
University College London (UCL)
P. Southern
University College London (UCL)
W. Szczerba
Akademia Gorniczo-Hutnicza im. Stanislawa Staszica w Krakowie
Bundesanstalt für Materialforschung und -prüfung (BAM)
Lunjie Zeng
Chalmers, Fysik, Eva Olsson Group
Kerstin Witte
Universität Rostock
Micromod Partikeltechnologie
C. Gruettner
Micromod Partikeltechnologie
F. Westphal
Micromod Partikeltechnologie
Dirk Honecker
Institut Laue-Langevin
D. Gonzalez-Alonso
Universidad de Cantabria
L. F. Barquin
Universidad de Cantabria
Christer Johansson
RISE Research Institutes of Sweden
Journal of Physical Chemistry C
1932-7447 (ISSN) 1932-7455 (eISSN)
Vol. 122 5 3068-3077Ämneskategorier
Annan fysik
Fusion, plasma och rymdfysik
Den kondenserade materiens fysik
Infrastruktur
Chalmers materialanalyslaboratorium
DOI
10.1021/acs.jpcc.7b11255