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Structural Disorder in Doped Zirconias, Part I: The Zr0.8Sc0.2-xYxO1.9 (0.0 ≤x ≤ 0.2) System

Stefan T. Norberg (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; S. Hull ; Istaq Ahmed (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; Sten G. Eriksson (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; D. Marrocchelli ; P. A. Madden ; P. Li ; J. T. S. Irvine
Chemistry of Materials (0897-4756). Vol. 23 (2011), 6, p. 1356-1364.
[Artikel, refereegranskad vetenskaplig]

The influence of local ordering of the anion vacancies and cation-anion vacancy interactions on the ionic conductivity of the anion-deficient fluorite Zr0.8Sc0.2-xYxO1.9 (0.0 <= x <= 0.2) system have been investigated using impedance spectroscopy, molecular dynamics (MD) simulations, and reverse Monte Carlo (RMC) analysis of neutron powder diffraction data. At 1000 K, the ionic conductivity decreases by a factor of similar to 2 as x increases from 0.0 to 0.2, while the oxygen anion partial radial distribution function, g(OO)(r), remains similar across the entire solid solution, even though the cation-oxygen interactions change with increasing Y2O3 content. These experimental data are used to validate the MD simulations, which probe the details of the vacancy-vacancy interactions within the x = 0.0 and x = 0.2 end members. Both possess similar vacancy-vacancy ordering that favors the formation of pairs along < 111 > directions. Significantly, an increased proportion of the oxygen vacancies are associated with the Zr4+ cations in Zr0.8Y0.2O1.9, while in Zr0.8Sc0.2O1.9 they show no significant preference for being nearest neighbor to a Sc3+ or a Zr4+ cation. Thus, it is concluded that the lower ionic conductivity at x = 0.2 is predominantly a consequence of the larger size of the Y3+ cation, which induces strain in the lattice and hinders diffusion of the O2-, rather than changes in the local ordering of the anion vacancies.

Nyckelord: RMC and MD modeling, neutron diffraction, oxygen vacancy ordering, doped zirconia (ZrO2), SOFC electrolytes, yttria-stabilized zirconia, oxide-ion conductor, fuel-cells, elevated-temperatures, neutron-scattering, diffuse-scattering, solid-solutions, phase-relationships, average structure, defect, structure



Denna post skapades 2011-04-08. Senast ändrad 2016-07-06.
CPL Pubid: 138846

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Oorganisk miljökemi (2005-2014)

Ämnesområden

Fysikalisk kemi

Chalmers infrastruktur