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Advanced Electron Microscopy Investigation of Ceria–Zirconia‐Based Catalysts
Author(s) -
LópezHaro M.,
PérezOmil J. A.,
HernándezGarrido J. C.,
Trasobares S.,
Hungría A. B.,
Cíes J. M.,
Midgley P. A.,
BayleGuillemaud P.,
MartínezArias A.,
Bernal S.,
Delgado J. J.,
Calvino J. J.
Publication year - 2011
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201000306
Subject(s) - scanning transmission electron microscopy , pyrochlore , materials science , cubic zirconia , dark field microscopy , transmission electron microscopy , high resolution transmission electron microscopy , crystallography , oxide , phase (matter) , nanotechnology , microscopy , chemistry , ceramic , metallurgy , physics , organic chemistry , optics
The potentials of advanced transmission and scanning transmission electron microscopy in nanostructural studies of ceria–zirconia mixed oxides are overviewed. The crystallographic criteria that allow us to discriminate the different CeO 2 –ZrO 2 polymorphs and the nanocrystal size range within which they can be applied are discussed. The combined use of high resolution electron microscopy (HREM) and high‐angle annular dark field scanning transmission electron microscopy (HAADF‐STEM) to detect disorder–order transitions in the cation sublattice of this family of oxides and the size limit down to which each of them can be used for that purpose are also analyzed. Criteria to discriminate, on the basis of HREM images, the oxygen arrangement of the so called κ‐Ce 2 Zr 2 O 8 phase from that of an oxidized pyrochlore Ce 2 Zr 2 O 8 phase are presented and applied to the interpretation of experimental HREM images. HAADF‐STEM tomography studies and detailed analysis of HAADF‐STEM images establish both the crystallographic and compositional features of the surfaces of the mixed oxides that give enhanced redox activity. These findings allow deeper understanding of the influence of different thermal ageing pretreatments on the redox behavior of this family of mixed oxides. Novel characterization data do evidence that this model does not only fruitfully apply to binary ceria–zirconia oxides but also to more complex ternary oxides containing terbium.