Fast-Ion Conduction and Disorder in Cation and Anion Arrays in Y2(ZryTi1−y)2O7 Pyrochlores Induced by Zr Substitution: A Neutron Rietveld Analysis

Structural refinements have been carried out on the Y2(ZryTi1−y)2O7 system for increasing amounts of Zr substitution. The structure changes from an ordered pyrochlore structure (superstructure of the fluorite structure) to an anion-deficient fluorite structure. Separate processes govern the disordering of the cation and anion arrays. In particular, the anions begin to disorder at lower values of y than the cations. For intermediate compositions, a minor amount of fluorite phase coexists with the primary partially-disordered pyrochlore phase.