Relating Magnetic Properties and High Hyperthermia Performance of Iron Oxide Nanoflowers
Journal article, 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.
Author
P. Bender
University of Cantabria
J. Fock
Technical University of Denmark (DTU)
C. Frandsen
Technical University of Denmark (DTU)
M. F. Hansen
Technical University of Denmark (DTU)
Christoph Balceris
Technische Universität Braunschweig
Frank Ludwig
Technische Universität Braunschweig
Oliver Posth
Physikalisch-Technische Bundesanstalt (PTB)
E. Wetterskog
Uppsala University
Lara K. Bogart
University College London (UCL)
P. Southern
University College London (UCL)
W. Szczerba
AGH University of Science and Technology
Federal Institute for Materials Research and Testing
Lunjie Zeng
Chalmers, Physics, Eva Olsson Group
Kerstin Witte
University of Rostock
Micromod Partikeltechnologie
C. Gruettner
Micromod Partikeltechnologie
F. Westphal
Micromod Partikeltechnologie
Dirk Honecker
Institut Laue-Langevin
D. Gonzalez-Alonso
University of Cantabria
L. F. Barquin
University of Cantabria
Christer Johansson
RISE Research Institutes of Sweden
Journal of Physical Chemistry C
1932-7447 (ISSN) 1932-7455 (eISSN)
Vol. 122 5 3068-3077Subject Categories
Other Physics Topics
Fusion, Plasma and Space Physics
Condensed Matter Physics
Infrastructure
Chalmers Materials Analysis Laboratory
DOI
10.1021/acs.jpcc.7b11255