Reduction and magnetic properties of nanocrystalline MgFe2O4/CuFe2O4 core/shell particles in flowing hydrogen at 400-700°C

Magnesium ferrite/copper ferrite core/shell nanoparticles obtained by a hydrothermal precipitation method were isothermally reduced in H 2 at 400-700°C. The reduced particles compacts were characterised by X-ray diffraction, electron and light microscopy, and vibrating sample magnetometry. Activatio...

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Bibliographic Details
Published in:Materials technology (New York, N.Y.) N.Y.), 2007-09, Vol.22 (3), p.133-138
Main Authors: Khedr, M. H., Bahgat, M., El Rouby, W. M . A.
Format: Article
Language:English
Subjects:
COATINGS
CORE-SHELL POWDERS
MAGNETIC PROPERTIES
NANOPARTICLES
REDUCTION KINETICS
REDUCTION MECHANISMS
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Summary:Magnesium ferrite/copper ferrite core/shell nanoparticles obtained by a hydrothermal precipitation method were isothermally reduced in H 2 at 400-700°C. The reduced particles compacts were characterised by X-ray diffraction, electron and light microscopy, and vibrating sample magnetometry. Activation energies calculated from the Arrhenius equation were 9˙67 kJ mol -1 for the initial stage of reduction and 30˙48 kJ mol -1 for the final stage. Kinetics were shown to be controlled by gaseous diffusion and a combined gaseous diffusion-interfacial chemical reaction mechanism in the initial and final stages respectively. The magnetic measurements indicated that increasing the reduction temperature decreased the coercivity and increased saturation magnetisation of the powders; remanent magnetisation was not affected by reduction temperature.
ISSN:1066-7857
1753-5557
DOI:10.1179/175355507X236623