Maghemite Interparticle Interactions in γ–Fe2O3/Ag nanocomposites
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Maghemite and silver nanoparticles were prepared using the ionic coordination reaction technique. X-ray diffractograms (XRD) show that all the samples have a high degree of purity. The average particle sizes obtained by XRD and transmission electron microscopy (TEM) vary from 9 to 13 nm for the γ–Fe2O3 particles and from 130 to 142 nm for the Ag particles. The magnetic properties of the samples have been studied by room-temperature DC magnetization and Mössbauer spectroscopy. These measurements indicate the presence of γ–Fe2O3 particles with interparticle interactions of varying strength, resulting in three magnetic regimes: superparamagnetic, superparamagnetic with interactions, and blocked with interactions.
KeywordsNanoparticles Maghemite Superparamagnetic Magnetic interactions
This work was supported by CNPQ, CAPES, and FAPERN. We thank Professor José Humberto de Araújo for facilitating access to the VSM magnetometer. Thanks are extended to CETENE for the electron microscopy analysis.