Structural Disorder in Doped Zirconias, Part I: The Zr0.8Sc0.2-xYxO1.9 (0.0 ≤x ≤ 0.2) System
Artikel i vetenskaplig tidskrift, 2011

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.

solid-solutions

doped zirconia (ZrO2)

defect

structure

diffuse-scattering

RMC and MD modeling

fuel-cells

yttria-stabilized zirconia

average structure

oxide-ion conductor

elevated-temperatures

phase-relationships

neutron-scattering

neutron diffraction

oxygen vacancy ordering

SOFC electrolytes

Författare

Stefan Norberg

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

S. Hull

ISIS Facility

Istaq Ahmed

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Sten Eriksson

Chalmers, Kemi- och bioteknik, Oorganisk miljökemi

Dario Marrocchelli

University of Edinburgh

Massachusetts Institute of Technology (MIT)

Paul Madden

University of Oxford

P. Li

University of St Andrews

Northwestern Polytechnical University

J. T. S. Irvine

University of St Andrews

Chemistry of Materials

0897-4756 (ISSN) 1520-5002 (eISSN)

Vol. 23 1356-1364

Ämneskategorier

Fysikalisk kemi

DOI

10.1021/cm102808k