Pyrochlore to fluorite transition: the y 2(ti1 xzrx)(2)o 7 (0.0 <= x <= 1.0) system
2012 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 24, no 22, 4294-4300 p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2012. Vol. 24, no 22, 4294-4300 p.
RMC modeling, oxygen vacancy ordering, SOFC electrolytes
Materials Chemistry Physical Chemistry
IdentifiersURN: urn:nbn:se:su:diva-88293DOI: 10.1021/cm301649dISI: 000313769300004OAI: oai:DiVA.org:su-88293DiVA: diva2:612182
FunderSwedish Research Council