Abstract

The magnetic properties of nanoparticles of gamma-Fe2O3 prepared by reverse micelles have been studied by dc magnetization, transverse ac susceptibility, and Mössbauer spectroscopy. The nanoparticles of gamma-Fe2O3 in the nanocomposite (gamma-Fe2O3)80Ag20 exhibit superparamagnetic behavior. The blocking temperatures determined by the three methods indicate the superparamagnetic nature of (gamma-Fe2O3)80Ag20 above 70-80 K and show correlation with measuring time. The average particle diameter obtained by transmission electron microscopy of the gamma-Fe2O3 particles is ~10 nm and that of the Ag particles is ~20 nm. The average particle size determined from the magnetic analyses for the gamma-Fe2O3 particles is ~12 nm. Mössbauer spectra obtained between 4.2 and 295 K clearly reveal the presence of superparamagnetic relaxation at temperatures above ~80 K. The Mössbauer spectra reveal at most 1% of paramagnetic Fe2+ ions in the 295-K spectrum.

Department(s)

Chemistry

Sponsor(s)

Louisiana Board of Regents
Sharp Laboratories of America

Keywords and Phrases

Mössbauer Effect; Coercive Force; Iron Compounds; Magnetic Particles; Magnetic Relaxation; Magnetic Susceptibility; Nanocomposites; Nanoparticles; Partical Size; Silver; Superparamagnetism; Transmission Electron Microscopy

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2005 American Institute of Physics (AIP), All rights reserved.

Full Text Link

Included in

Chemistry Commons

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