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Title: Investigation of magnetic properties of Fe{sub 3}O{sub 4} nanoparticles using temperature dependent magnetic hyperthermia in ferrofluids

Rate of heat generated by magnetic nanoparticles in a ferrofluid is affected by their magnetic properties, temperature, and viscosity of the carrier liquid. We have investigated temperature dependent magnetic hyperthermia in ferrofluids, consisting of dextran coated superparamagnetic Fe{sub 3}O{sub 4} nanoparticles, subjected to external magnetic fields of various frequencies (188–375 kHz) and amplitudes (140–235 Oe). Transmission electron microscopy measurements show that the nanoparticles are polydispersed with a mean diameter of 13.8 ± 3.1 nm. The fitting of experimental dc magnetization data to a standard Langevin function incorporating particle size distribution yields a mean diameter of 10.6 ± 1.2 nm, and a reduced saturation magnetization (∼65 emu/g) compared to the bulk value of Fe{sub 3}O{sub 4} (∼95 emu/g). This is due to the presence of a finite surface layer (∼1 nm thickness) of non-aligned spins surrounding the ferromagnetically aligned Fe{sub 3}O{sub 4} core. We found the specific absorption rate, measured as power absorbed per gram of iron oxide nanoparticles, decreases monotonically with increasing temperature for all values of magnetic field and frequency. Using the size distribution of magnetic nanoparticles estimated from the magnetization measurements, we have fitted the specific absorption rate versus temperature data using a linear response theory and relaxation dissipation mechanisms to determine the value of magnetic anisotropymore » constant (28 ± 2 kJ/m{sup 3}) of Fe{sub 3}O{sub 4} nanoparticles.« less
Authors:
; ; ;  [1] ;  [2] ;  [3]
  1. Department of Physics and Astronomy, Wayne State University, Detroit, Michigan 48202 (United States)
  2. Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, Michigan 48128 (United States)
  3. Department of Physics, Kettering University, Flint, Michigan 48504 (United States)
Publication Date:
OSTI Identifier:
22308497
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; ABSORPTION; ANISOTROPY; CARRIERS; DISTRIBUTION; IRON OXIDES; LAYERS; MAGNETIC FIELDS; MAGNETIC PROPERTIES; MAGNETIZATION; NANOPARTICLES; PARTICLE SIZE; RELAXATION; SATURATION; SPIN; SUPERPARAMAGNETISM; SURFACES; TEMPERATURE DEPENDENCE; THICKNESS; TRANSMISSION ELECTRON MICROSCOPY; VISCOSITY