Characterization of nanosized maghemite particles prepared by microemulsion using an ionic surfractant

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

HYPERFINE INTERACTIONS

Springer Netherlands

Año: 2003 vol. 148- p. 103 - 108

0304-3843

We have characterized a system of maghemite, γ-Fe2O3, 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  aprox.150 K. The real component of the AC susceptibility (5<(nu)<104 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.