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Highly sinter-active nanocrystalline RE2O3 (RE = Gd, Eu, Dy) by a combustion process, and role of oxidant-to-fuel ratio in preparing their different crystallographic modifications

Published online by Cambridge University Press:  03 March 2011

V. Bedekar ,
S.V. Chavan  and
A.K. Tyagi
V. Bedekar
Affiliation:
Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
S.V. Chavan
Affiliation:
Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
A.K. Tyagi*
Affiliation:
Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
*
a) Address all correspondence to this author. e-mail: [email protected]
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Abstract

Highly sinter-active powders of RE2O3 [rare earth (RE) = Gd, Eu, Dy] have been prepared using the corresponding metal nitrates as the oxidants, and glycine and citric acid as the fuels. Two different oxidant-to-fuel ratios, namely stoichiometric ratio and fuel-deficient ratio were used to explore the possibility of preparing different crystallographic modifications. By a careful control of oxidant-to-fuel ratio, nanocrystalline Eu2O3 and Gd2O3 could be prepared in cubic (C-type) as well as monoclinic (B-type) modifications. However, the high-temperature monoclinic modification could not be obtained for Dy2O3 due to a very high C-to-B-type phase transition temperature. The crystallite size, surface area, and sintering behavior were also studied for powders prepared using different oxidant-to-fuel ratios, and the results showed a remarkable correlation between different fuel contents and powder properties. Some of these powders resulted in pellets of nearly theoretical density. The sintered microstructure was studied by scanning electron microscopy.

Keywords

Combustion synthesisNanoscalePhase transformation
Type
Articles
Information
Journal of Materials Research , Volume 22 , Issue 3 , March 2007 , pp. 587 - 594
Copyright
Copyright © Materials Research Society 2007

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