The fluorite-pyrochlore transformation of Ho2-yNdyZr2O7
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Date
2011-08-01
Journal Title
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Publisher
Elsevier
Abstract
Twelve members of the Ho2-yNdyZr2O7 series, prepared using conventional solid state methods, have been characterised by neutron powder diffraction. Ho2Zr2O7 has a defect fluorite structure whereas Nd2Zr2O7 is found to adopt the ordered pyrochlore structure with the composition induced fluorite-pyrochlore transformation occurring near y=1. Rietveld analysis on the neutron data for all the compositions reveals an increase in lattice parameter as a function of y across the entire series, with a small discontinuity associated with the transformation. The neutron profile results suggest that domains of pyrochlore-type initially begin to form before crystallising into a separate phase, and therefore that anion and cation ordering processes are distinct. There is a strong correlation between the extent of disorder in the anion sublattice and the x-parameter of 48f oxygen. These results point the way to a better understanding of the stability observed in pyrochlore structures.(C) 2011 Elsevier Inc.
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Keywords
Neutron diffraction, Fluorite, Transformations, Defects, Pyrochlore, Synchrotrons
Citation
Clements, R., Hester, J.R., Kennedy, B.J., Ling, C.D., Stampfl, A.P.J. (2011), The fluorite-pyrochlore transformation of Ho2-yNdyZr2O7, Journal of Solid State Chemistry, 84(8), 2108-2113. doi:10.1016/j.jssc.2011.05.054