Characterization of Nanosized Maghemite ParticlesPrepared by Microemulsion Using an IonicSurfactant

M.J. TUEROS; L.A. BAUM; R.A. BORZI; S.J. STEWART; R.C. MERCADER; S.G. MARCHETTI; J.F. BENGOA; L.V. MOGNI

HYPERFINE INTERACTIONS

Springer

Año: 2003 vol. 148 p. 103 - 108

0304-3843

Abstract. We have characterized a system of maghemite, γ -Fe2 O3 , nanosized particles prepared by a microemulsion method using an ionic surfactant. The Mössbauer spectra from 21 to 298 K evolve from a totally magnetically split signal at low temperatures to a single superparamagnetic (sp) doublet at 298 K with a blocking temperature of ≈150 K. The real component of the AC susceptibility (5Hz< ν< 10E4 Hz) displays a behavior characteristic of a system of interacting particles. A broad distribution of the particle sizes is revealed by the much higher average energy barrier obtained by AC susceptibility than Mössbauer.