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Synthesis of ceramic oxide powders in a microwave plasma device

Published online by Cambridge University Press:  03 March 2011

Dieter Vollath  and
Kurt E. Sickafus
Dieter Vollath
Affiliation:
Kernforschungszentrum Karlsruhe, Institut für Materialforschung, P.O. Box 3640, D-76021 Karlsruhe, Germany
Kurt E. Sickafus
Affiliation:
Los Alamos National Laboratory, Los Alamos, New Mexico 87545
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Abstract

Synthesizing oxide ceramic powders by application of a microwave plasma is a great advantage. There are two ways the microwave plasma can be used: The first is as a source of heat for the pyrolysis of solutions and the second is to excite gas reactions to obtain nanosized powders. Both applications are superior to standard methods. A microwave cavity well suited for these experiments and its operating characteristics are described. Using a microwave plasma as a source of heat for pyrolytic decomposition of nitrates in aqueous solutions leads to a fine-grained product with particle sizes from 100 to 1000 nm. Crystallite sizes in those particles are in most cases less than 10 nm. This is demonstrated with zirconia-based ceramics, such as ZrO2−3 mol % Y2O3−20 mol % Al2O3. Depending on the conditions during pyrolysis, it is possible to obtain a product in which alumina is either dissolved in zirconia or the onset of the phase separation is observed. The energy efficiency of this process is better than 80%. If the reactants are gaseous, e.g., ZrCl4, it is possible to produce powders with mean particle sizes of about 4 nm. In the case of zirconia, these particles are monocrystalline with a cubic structure. This structure is not in equilibrium under the experimental conditions.

Type
Articles
Information
Journal of Materials Research , Volume 8 , Issue 11 , November 1993 , pp. 2978 - 2984
Copyright
Copyright © Materials Research Society 1993

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References

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