Specificity of the Local Structure of Nanocrystalline Doped Ceria Solid Electrolytes Conference Abstracts
Conference |
2004 MRS Fall Meeting 29 Nov - 2 Dec 2004 , Boston |
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Source | Abstracts, 2004 MRS Fall Meeting & Exhibit, November 29 - December 3, 2004, Boston Compilation, 2004. |
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Output data | Year: 2004, Article number : K3.6, Pages count : 1 | ||||||
Authors |
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Affiliations |
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Funding (2)
1 | International Science and Technology Center | 2529 |
2 | International Association for the Promotion of Co-operation with Scientists from the New Independent States of the Former Soviet Union | 01-2162 |
Abstract:
Nanocrystalline ceria solid solutions are now of a great interest due to their easy sintering into mechanically strong dense submicron ceramics as well as specific defect/transport properties associated with high surface/grain boundary areas. However, still little is known about specificity of their real/defect structure due to difficulties of its characterization by traditional diffraction methods. This work presents results of studies of the structural features of nanocrystalline doped Ce1-xMeOx02-y samples (Me= Sm, Bi, Gd; x = 0-0.5) prepared via the polymerised precursor (Pechini) route by using a combination of diffraction (XRD, TEM, WAXS on SR) and spectroscopic (EXAFS, Raman, FTIRS of lattice modes, XPS, SIMS) methods. According to X-ray diffraction data, all these samples are single-phase fluorite-like solid solutions, their lattice constants linearly increasing with the dopant content, while domain sizes declining.
High-resolution TEM data confirm a good nanodomains crystallinity. However, the local structure around Ce and dopant cations studied by EXAFS and WAXS on synchrotron radiation was found to be strongly distorted even in pure nanocrystalline ceria depending upon the type and content of a dopant as well. Progressive disordering of the lattice
with the dopant content is also reflected in decline of the intensity of EXAFS peaks. At a high dopant content, a local rearrangement of the structure into that of a lower symmetry is reflected in appearance of new EXAFS peaks and splitting of the Raman and IR bands. Analysis of the amplitudes of peaks assigned to different coordination spheres
and corresponding distances revealed the most uniform distribution in the ceria lattice for smallest Gd cations. In addition, for Gd doped ceria, anion vacancies appear to be preferentially located in the coordination sphere of Ce cations, while they are mainly associated with bigger dopants. Comparison with the published data on the local
structure of dense coarse-grained ceria-based electrolytes with the same composition revealed a higher flexibility of the nanocrystalline systems structure, which can be assigned to the effects of domain boundaries and free surfaces. Segregation of dopants at the surface/domain boundaries revealed by SIMS and XPS could play here some role. However, the lattice oxygen mobility estimated by dynamic isotope exchange appears to correlate with the density of free anion vacancies located in the coordination sphere of Ce cations and not with the density of domain boundaries. This work is in part supported by INTAS 01-2162 and ISTC 2529 Projects. DAAD postdoctoral research scholarship to H.B. is acknowledged.
Cite:
Sadykov V.A.
, Frolova Y.V.
, Kriventsov V.V.
, Kochubei D.I.
, Moroz E.M.
, Zyuzin D.A.
, Potapova Y.V.
, Muzykantov V.S.
, Zaikovskii V.I.
, Burgina E.B.
, Borchert H.
, Neophytides S.
, Kemnitz E.
, Scheurell K.
Specificity of the Local Structure of Nanocrystalline Doped Ceria Solid Electrolytes
In compilation Abstracts, 2004 MRS Fall Meeting & Exhibit, November 29 - December 3, 2004, Boston. 2004. – C.289.
Specificity of the Local Structure of Nanocrystalline Doped Ceria Solid Electrolytes
In compilation Abstracts, 2004 MRS Fall Meeting & Exhibit, November 29 - December 3, 2004, Boston. 2004. – C.289.
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