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Phase separation and surface segregation in ceria-zirconia solid solutions

Grau-Crespo, R., de Leeuw, N. H., Hamad, S. and Waghmare, U. V. (2011) Phase separation and surface segregation in ceria-zirconia solid solutions. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 467 (2131). pp. 1925-1938. ISSN 1364-5021

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To link to this item DOI: 10.1098/rspa.2010.0512

Abstract/Summary

Using a combination of density functional theory calculations and statistical mechanics, we show that a wide range of intermediate compositions of ceria – zirconia solid solutions are thermodynamically metastable with respect to phase separation into Ce-rich and Zr-rich oxides. We estimate that the maximum equilibrium concentration of Zr in CeO2 at 1373 K is ~2%, and therefore equilibrated samples with higher Zr content are expected to exhibit heterogeneity at the atomic scale. We also demonstrate that in the vicinity of the (111) surface, cation redistribution at high temperatures will occur with significant Ce enrichment of the surface, which we attribute to the more covalent character of Zr-O bonds compared to Ce-O bonds. Although the kinetic barriers for cation diffusion normally prevent the decomposition/segregation of ceria-zirconia solid solutions in typical catalytic applications, the separation behaviour described here can be expected to occur in modern three-way catalytic converters, where very high temperatures are reached.

Item Type:Article
Refereed:Yes
Divisions:No Reading authors. Back catalogue items
Faculty of Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
ID Code:36089
Publisher:Royal Society Publishing

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