The structure and the magnetic properties of a series of Fe2O3-SiO2 nanocomposites (16.9 and 28.5 wt% of Fe2O3/(Fe2O3 + SiO2)), prepared by a sol-gel method and submitted to thermal treatments in a temperature range 300-700 degreesC, were investigated through X-ray diffraction (XRD), transmission electron microscopy (TEM), Mossbauer spectroscopy and magnetometry. Poorly crystallized particles, belonging to the 2-line ferrihydrite phase, were found in all the samples and recognized as precursors of the gamma -Fe2O3 that form in Fe2O3-SiO2 nanocomposites at T > 700 degreesC. The result was achieved through a detailed comparison of structural and magnetic properties of nanocomposites with a bulk iron (III) oxide hydrated reference sample. (C) 2001 Elsevier Science B.V. All rights reserved.
Investigation of the precursors of gamma-Fe2O3 in Fe2O3/SiO2 nanocomposites obtained through sol-gel
CANNAS, CARLA;CONCAS, GIORGIO;FALQUI, ANDREA;MUSINU, ANNA MARIA GIOVANNA;
2001-01-01
Abstract
The structure and the magnetic properties of a series of Fe2O3-SiO2 nanocomposites (16.9 and 28.5 wt% of Fe2O3/(Fe2O3 + SiO2)), prepared by a sol-gel method and submitted to thermal treatments in a temperature range 300-700 degreesC, were investigated through X-ray diffraction (XRD), transmission electron microscopy (TEM), Mossbauer spectroscopy and magnetometry. Poorly crystallized particles, belonging to the 2-line ferrihydrite phase, were found in all the samples and recognized as precursors of the gamma -Fe2O3 that form in Fe2O3-SiO2 nanocomposites at T > 700 degreesC. The result was achieved through a detailed comparison of structural and magnetic properties of nanocomposites with a bulk iron (III) oxide hydrated reference sample. (C) 2001 Elsevier Science B.V. All rights reserved.
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