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Coulometric Titration Studies of Nonstoichiometric Nanocrystalline Ceria

Published online by Cambridge University Press:  10 February 2011

O. Porat ,
H. L. Tuller ,
E. B. Lavik  and
Y.-M. Chiang
O. Porat
Affiliation:
Center for Materials Science & Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
H. L. Tuller
Affiliation:
Center for Materials Science & Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
E. B. Lavik
Affiliation:
Center for Materials Science & Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
Y.-M. Chiang
Affiliation:
Center for Materials Science & Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
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Abstract

Oxygen nonstoichiometry measurements in nanocrystalline ceria, x in CeO2-x, were performed using coulometric titration. The measurements reveal large apparent deviations from stoichiometry, of the order of 10−3 − 10−4 at T = 405 − 455 °C and Po2 = 0.21 − 10−5 atm, as compared to levels of ∼10−9 for coarsened materials under the same conditions. The level of nonstoichiometry is, however, larger then expected from previous electrical conductivity data of nanocrystalline ceria. In addition, x ∝ Po2−½ while Σ ∝po2−1/6. The observed dependence of x(Po2, T) can be explained by either the formation of neutral oxygen vacancies at or near the interface, or by surface adsorption.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 457: Symposium V – Nanophase and Nanocomposite Materials II , 1996 , 99
Copyright
Copyright © Materials Research Society 1997

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References

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