Characterizarion of nanosized maghemite particles prepared by microemulsion using an ionic surfactant

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

Hyperfine Interactions

Año: 2003 vol. 148 p. 103 - 108

0304-3843

We have characterized a system of maghemite, γ -Fe2O3, nanosized particles preparedby a microemulsion method using an ionic surfactant. The Mössbauer spectra from 21 to 298 Kevolve 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 (5 ν 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.