Pyrochlore to Fluorite Transition: The Y2(Ti1-xZrx)2O7 (0.0 ≤ x ≤ 1.0) System
Journal article, 2012

The structural properties of the system Y-2(Ti1-xZrx)(2)O-7 have been investigated using the neutron powder diffraction technique, including a detailed analysis of the "total scattering" using reverse Monte Carlo modeling to probe the short-range ion-ion correlations over sample range 0.0 <= x <= 1.0. The average crystal structure shows a continuous transformation from the long-range ordered pyrochlore structure (Fd (3) over barm, a = 10.0967(1) angstrom, Z = 8, for x = 0.00, Y2Ti2O7) to a disordered fluorite structure (Fm (3) over barm, a = 5.2042(1) angstrom, Z = 1, for x = 1.00, Zr2Y2O7) in agreement with previous reports. However, on increasing x the disordering of both the cation and the anion sublattices occurs in stages, with the Zr4+ initially only substituting onto the Ti4+ site and adopting a cubic, rather than octahedral, local anion environment. At concentrations in excess of x approximate to 0.4 there is a gradual disordering of the Y3+, Ti4+, and Zr4+ species over all the cation sites, coupled with a redistribution of the O2- which initially only involves those anions on the O1 sites. The relationship between the composition dependences of the structure properties and the ionic conductivity is discussed.

zro2-tio2-y2o3 system

chemistry

oxygen vacancy ordering

electrical-conductivity

titania

oxygen-ion

y2ti2o7

oxide fuel-cells

zirconia

phase

anode materials

RMC modeling

SOFC electrolytes

Author

Stefan Norberg

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

S. Hull

ISIS Facility

Sten Eriksson

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

Istaq Ahmed

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

FRANCIS GACHAO KINYANJUI

Chalmers, Chemical and Biological Engineering, Environmental Inorganic Chemistry

J. J. Biendicho

ISIS Facility

Stockholm University

Chemistry of Materials

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

Vol. 24 22 4294-4300

Subject Categories

Chemical Sciences

DOI

10.1021/cm301649d

More information

Latest update

3/1/2018 7