Probing long- and short-range disorder in Y2Ti2–xHfxO7 by diffraction and spectroscopy techniques

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dc.contributor.authorZhang, ZMen_AU
dc.contributor.authorAvdeev, Men_AU
dc.contributor.authorde los Reyes, Men_AU
dc.contributor.authorLumpkin, GRen_AU
dc.contributor.authorKennedy, BJen_AU
dc.contributor.authorBlanchard, PERen_AU
dc.contributor.authorLiu, Sen_AU
dc.contributor.authorTadich, Aen_AU
dc.contributor.authorCowie, BCCen_AU
dc.date.accessioned2021-02-03T22:38:03Zen_AU
dc.date.available2021-02-03T22:38:03Zen_AU
dc.date.issued2016-11-01en_AU
dc.date.statistics2021-01-12en_AU
dc.description.abstractWe studied the long-range average and short-range local structures in Y2Ti2–xHfxO7 (x = 0–2.0) using diffraction and spectroscopy techniques, respectively. Both neutron and synchrotron X-ray powder diffraction data show a clear phase transition of the average structure from ordered pyrochlore to disordered defect-fluorite at x ≈ 1.6; the long-range anion disorder appears to develop gradually throughout the entire pyrochlore region in contrast to the rapid loss of cation ordering from x = 1.4 to 1.6. The commonly observed two-phase region around the pyrochlore/defect-fluorite phase boundary is absent in this system, demonstrating high sample quality. X-ray absorption near-edge structure (XANES) results at the Y L2-, Ti K- and L3,2-, Hf L3-, and O K-edges indicate a gradual local structural evolution across the whole compositional range; the Y coordination number (CN) decreases and the CN around Ti and Hf increases with increasing Hf content (x). The spectroscopic results suggest that the local disorder occurs long before the pyrochlore to defect-fluorite phase boundary as determined by diffraction, and this disorder evolves continuously from short- to medium- and eventually to long-range detectable by diffraction. This study highlights the complex disordering process in pyrochlore oxides and the importance of a multitechnique approach to tackle disorder over different length scales and in the anion and cation sublattices, respectively. The results are important in the context of potential applications of these oxides such as ionic conductors and radiation-resistant nuclear waste forms. © 2016 American Chemical Societyen_AU
dc.identifier.citationZhang, Z., Avdeev, M., de los Reyes, M., Lumpkin, G. R., Kennedy, B. J., Blanchard, P. E. R., Liu, S., Tadich, A., & Cowie, B. C. C. (2016). Probing long- and short-range disorder in Y2Ti2–xHfxO7 by diffraction and spectroscopy techniques. Journal of Physical Chemistry C, 120(46), 26465–26479. doi:10.1021/acs.jpcc.6b07076en_AU
dc.identifier.issn1932-7455en_AU
dc.identifier.issue46en_AU
dc.identifier.journaltitleJournal of Physical Chemistry Cen_AU
dc.identifier.pagination26465-26479en_AU
dc.identifier.urihttps://doi.org/10.1021/acs.jpcc.6b07076en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/10292en_AU
dc.identifier.volume120en_AU
dc.language.isoenen_AU
dc.publisherAmerican Chemical Societyen_AU
dc.subjectX-ray spectroscopyen_AU
dc.subjectNeutron diffractionen_AU
dc.subjectX-ray diffractionen_AU
dc.subjectPhase transformationsen_AU
dc.subjectPyrochloreen_AU
dc.subjectFluoriteen_AU
dc.subjectCationsen_AU
dc.subjectAnionsen_AU
dc.subjectOxidesen_AU
dc.subjectCrystal latticesen_AU
dc.subjectWaste formsen_AU
dc.titleProbing long- and short-range disorder in Y2Ti2–xHfxO7 by diffraction and spectroscopy techniquesen_AU
dc.typeJournal Articleen_AU
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