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 NĂ©el 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

Micromod Partikeltechnologie

University of Rostock

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 3068-3077

Subject Categories

Other Physics Topics

Fusion, Plasma and Space Physics

Condensed Matter Physics

DOI

10.1021/acs.jpcc.7b11255

More information

Latest update

10/3/2019