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

Journal Article · Mon Jul 21 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4890456· OSTI ID:22308497

Nemala, H.; Thakur, J. S.; Lawes, G.; Naik, V. M. ^[1]; Vaishnava, P. P. ^[2]

---

1. Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, Michigan 48128 (United States)
2. Department of Physics, Kettering University, Flint, Michigan 48504 (United States)

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 anisotropy constant (28 ± 2 kJ/m{sup 3}) of Fe{sub 3}O{sub 4} nanoparticles.

• OSTI ID: 22308497
• Journal Information: Journal of Applied Physics, Vol. 116, Issue 3; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

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