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Title: Anisotropy effects in magnetic hyperthermia: A comparison between spherical and cubic exchange-coupled FeO/Fe{sub 3}O{sub 4} nanoparticles

Spherical and cubic exchange-coupled FeO/Fe{sub 3}O{sub 4} nanoparticles, with different FeO:Fe{sub 3}O{sub 4} ratios, have been prepared by a thermal decomposition method to probe anisotropy effects on their heating efficiency. X-ray diffraction and transmission electron microscopy reveal that the nanoparticles are composed of FeO and Fe{sub 3}O{sub 4} phases, with an average size of ∼20 nm. Magnetometry and transverse susceptibility measurements show that the effective anisotropy field is 1.5 times larger for the cubes than for the spheres, while the saturation magnetization is 1.5 times larger for the spheres than for the cubes. Hyperthermia experiments evidence higher values of the specific absorption rate (SAR) for the cubes as compared to the spheres (200 vs. 135 W/g at 600 Oe and 310 kHz). These observations point to an important fact that the saturation magnetization is not a sole factor in determining the SAR and the heating efficiency of the magnetic nanoparticles can be improved by tuning their effective anisotropy.
Authors:
; ; ; ;  [1] ;  [1] ;  [2] ; ;  [3] ;  [2]
  1. Department of Physics, University of South Florida, Tampa, Florida 33620 (United States)
  2. (Spain)
  3. BCMaterials Edificio No. 500, Parque Tecnológico de Vizcaya, Derio 48160 (Spain)
Publication Date:
OSTI Identifier:
22403031
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; ANISOTROPY; COMPARATIVE EVALUATIONS; CUBIC LATTICES; FERRITES; HYPERTHERMIA; IRON OXIDES; KHZ RANGE; MAGNETIC SUSCEPTIBILITY; MAGNETIZATION; NANOPARTICLES; SPHERICAL CONFIGURATION; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION