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Characterization of Nanocrystalline γ–Fe2O3 Prepared by Wet Chemical Method

Published online by Cambridge University Press:  31 January 2011

G. Ennas*
Affiliation:
Dipartimento di Scienze Chimiche, Universitá degli studi di Cagliari, Via Ospedale 72, I-09124 Cagliari, Italy
G. Marongiu
Affiliation:
Dipartimento di Scienze Chimiche, Universitá degli studi di Cagliari, Via Ospedale 72, I-09124 Cagliari, Italy
A. Musinu
Affiliation:
Dipartimento di Scienze Chimiche, Universitá degli studi di Cagliari, Via Ospedale 72, I-09124 Cagliari, Italy
A. Falqui
Affiliation:
Consorzio Promea, V.le R.Margherita 30, I-09124 Cagliari, Italy
P. Ballirano
Affiliation:
Dipartimento di Chimica, Istituto Nazionale di Fisica della Materia, Universitá degli studi di Roma “La Sapienza, ” P.le A.Moro 5, I-00185 Roma, Italy
R. Caminiti
Affiliation:
Dipartimento di Chimica, Istituto Nazionale di Fisica della Materia, Universitá degli studi di Roma “La Sapienza, ” P.le A.Moro 5, I-00185 Roma, Italy
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

Homogeneous maghemite (γ–Fe2O3) nanoparticles with an average crystal size around 5 nm were synthesized by successive hydrolysis, oxidation, and dehydration of tetrapyridino-ferrous chloride. Morphological, thermal, and structural properties were investigated by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and x-ray diffraction (XRD) techniques. Rietveld refinement indicated a cubic cell. The superstructure reflections, related to the ordering of cation lattice vacancies, were not detected in the diffraction pattern. Kinetics of the solid-state phase transition of nanocrystalline maghemite to hematite (α–Fe2O3), investigated by energy dispersive x-ray diffraction (EDXRD), indicates that direct transformation from nanocrystalline maghemite to microcrystalline hematite takes place during isothermal treatment at 385 °C. This temperature is lower than that observed both for microcrystalline maghemite and for nanocrystalline maghemite supported on silica.

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Articles
Copyright
Copyright © Materials Research Society 1999

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References

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