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Fe–Cr/Al2O3 metal-ceramic composites: Nature and size of the metal particles formed during hydrogen reduction

Published online by Cambridge University Press:  03 March 2011

Ch. Laurent
Affiliation:
Laboratoire de Chimie des Materiaux Inorganiques, URA CNRS 1311, Université Paul-Sabatier, 31062 Toulouse Cedex, France
J.J. Demai
Affiliation:
Laboratoire de Chimie des Materiaux Inorganiques, URA CNRS 1311, Université Paul-Sabatier, 31062 Toulouse Cedex, France
A. Rousset
Affiliation:
Laboratoire de Chimie des Materiaux Inorganiques, URA CNRS 1311, Université Paul-Sabatier, 31062 Toulouse Cedex, France
K.R. Kannan
Affiliation:
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
C.N.R. Rao*
Affiliation:
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
*
a)Author to whom correspondence should be addressed.
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Abstract

Fe-Cr/Al2O3 metal-ceramic composites prepared by hydrogen reduction at different temperatures and for different periods have been investigated by a combined use of Mössbauer spectroscopy, x-ray diffraction, transmission electron microscopy, and energy-dispersive x-ray spectroscopy in order to obtain information on the nature of the metallic species formed. Total reduction of Fe3+ does not occur by increasing the reduction time at 1320 K from 1 to 30 h, and the amount of superparamagnetic metallic species is essentially constant (about 10%). Temperatures higher than 1470 K are needed to achieve nearly total reduction of substitutional Fe3+. Interestingly, iron favors the reduction of chromium. The composition of the Fe-Cr particles is strongly dependent on their size, the Cr content being higher in particles smaller than 10 nm.

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Articles
Copyright
Copyright © Materials Research Society 1994

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References

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