کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1330704 | 978971 | 2011 | 6 صفحه PDF | دانلود رایگان |
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.
Neutron diffraction profiles for Nd2−yHoyZr2O7 type oxides reveal details of the transformation from the ordered pyrochlore structure (y=0) to the disordered fluorite structure (y=2).Figure optionsDownload as PowerPoint slideHighlights
► Structures of twelve members of the Ho2−yNdyZr2O7 series studied using neutron powder diffraction.
► Domains of pyrochlore-type materials form at low doping levels.
► Higher doping stabilises the pyrochlore.
► Anion and cation ordering processes are distinct.
Journal: Journal of Solid State Chemistry - Volume 184, Issue 8, August 2011, Pages 2108–2113