ISSN:
1662-9779
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Physics
Notes:
The real structure of nanocrystalline CeO2-ZrO2 (Ce:Zr=1:1) systems prepared via thepolymerized polyester precursor (Pechini) route and doped with La3+ or Gd3+ cations, up to 30at.%, was studied by X-ray powder diffraction, EXAFS and Raman spectroscopy and the surfacefeatures characterized by XPS and SIMS. Undoped CeO2-ZrO2 system revealed nanoscaleheterogeneity, perhaps due to the co-existence of Zr- or Ce-enriched domains. With large La3+dopant the system remains bi-phasic within the studied ranges of composition, incorporation of thesmaller Gd3+ cation stabilizes the single-phase solid solution. For both systems, the increase ofdopant content was accompanied by a decline of domain size and an increase of the average latticeparameter of fluorite-like phases. Depletion of the surface layer by smaller Zr4+ cations wasobserved, while the surface content of a doping cation is either, close to that in the bulk (La) orbelow it (Gd). Such a spatial distribution of components results in some ordering of cations withinthe lattice. It is reflected in different modes of rearrangement of oxygen coordination polyhedrawith the Gd or La content (distances and coordination numbers by EXAFS), and specificity of XRDpatterns not conforming to a simple model with statistical distribution of oxygen vacancies
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/24/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.128.81.pdf
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