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Title: Modulation of Magnetic Heating via Dipolar Magnetic Interactions in Monodisperse and Crystalline Iron Oxide Nanoparticles

Here, we report on the study of heat dissipation power in monodisperse and crystalline magnetite nanoparticles as function of particle and aggregate sizes, magnetic field frequencies (up to 435 kHz) and amplitudes (up to 50 mT), media viscosity and particle concentration. These nanoparticles display specific absorption rate values of few hundreds of WgFe-1 at moderate frequencies (~100 kHz), increasing up to 3632 WgFe-1 at more extreme field conditions (430 kHz and 40 mT) for the largest size. We have found that Néelian relaxation processes are dominant for all nanoparticle sizes, whereas Brownian contribution dominates only for the largest size (22 nm) at high particle concentrations when dipolar interactions enhance the effective magnetic anisotropy. Besides, the particle concentration dependence of the specific absorption rate reflects the importance of magnetic dipolar interactions which strongly depend on aggregate and particle size. Our results show that dipolar interactions tune the effective magnetic anisotropy determining the Néelian and Brownian contributions into SAR values. The possibility of switching between heating mechanisms via dipolar interactions is of great importance towards controlling the heat exposure supplied by IONP as intracellular heating mediators.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [6] ;  [6] ;  [7] ;  [8] ;  [9]
  1. Univ. of Cantoblanco, Madrid (Spain). IMDEA nanoscience; Univ. of Cantoblanco, Madrid (Spain). Institute of Materials Science of Madrid-CSIC
  2. Univ. of Cantoblanco, Madrid (Spain). IMDEA nanoscience; Autonomous University of Madrid, Madrid (Spain)
  3. Univ. of Cantoblanco, Madrid (Spain). IMDEA Nanoscience
  4. Univ. of Cantoblanco, Madrid (Spain). IMDEA Nanoscience and Institute of Materials Science of Madrid-CSIC
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Univ. Complutense Madrid (Spain)
  6. Friedrich Schiller Univ., Jena (Germany)
  7. Univ. of Cantoblanco, Madrid (Spain). IMDEA Nanoscience; Autonomous University of Madrid, Madrid (Spain)
  8. Univ. of Cantoblanco, Madrid (Spain). Institute of Materials Science of Madrid-CSIC
  9. Univ. of Cantoblanco, Madrid (Spain). IMDEA nanoscience ; Univ. of Cantoblanco, Madrid (Spain). Associated Unit of Nanobiotechnology CNB-CSUC & IMDEA Nanoscience
Publication Date:
OSTI Identifier:
1162068
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 118; Journal Issue: 34; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY iron oxide nanoparticles; magnetic heating; magnetic dipolar interactions; magnetic effective anisotropy