Local structural correlations in heavy rare-earth zirconates A2Zr2O7

Rare-earth A2Zr2O7 zirconates have been generally considered to crystallize with either long range ordered pyrochlore structure or disordered defect-fluorite structure, empirically depending on the size ratio between A and Zr cations. However, on a local scale, the ‘defect-fluorite’ members of the series have been discussed to reveal a lower-symmetry structure. Recently, our neutron and x-ray pair-distribution function studies of local structure correlations in the series suggested that the short-range environment of the nominally ‘defect-fluorite’ members is similar to the rhombohedral structure of the end-member Lu2Zr2O7. To unambiguously reveal subtle structural aspects in the A2Zr2O7 series, our PDF results are still to be corroborated by other local-environment sensitive techniques, namely the proposed EXAFS experiment.