Bi1−xNbxO1.5+x (x=0.0625, 0.12) fast ion conductors: structures, stability and oxide ion migration pathways

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dc.contributor.authorTate, MLen_AU
dc.contributor.authorHack, Jen_AU
dc.contributor.authorKuang, Xen_AU
dc.contributor.authorMcIntyre, GJen_AU
dc.contributor.authorWithers, RLen_AU
dc.contributor.authorJohnson, MRen_AU
dc.contributor.authorEvans, IRen_AU
dc.date.accessioned2021-12-20T21:04:58Zen_AU
dc.date.available2021-12-20T21:04:58Zen_AU
dc.date.issued2015-05en_AU
dc.date.statistics2021-12-09en_AU
dc.description.abstractA combined experimental and computational study of Bi1−xNbxO1.5+x (x=0.0625 and 0.12) has been carried out using laboratory X-ray, neutron and electron diffraction, impedance measurements and ab-initio molecular dynamics. We demonstrate that Bi0.9375Nb0.0625O1.5625, previously reported to adopt a cubic fluorite-type superstructure, can form two different polymorphs depending on the synthetic method: a metastable cubic phase is produced by quenching; while slower cooling yields a stable material with a tetragonal √2×√2×1 superstructure, which undergoes a reversible phase transition into the cubic form at ~680 °C on subsequent reheating. Neutron diffraction reveals that the tetragonal superstructure arises mainly from ordering in the oxygen sublattice, with Bi and Nb remaining disordered, although structured diffuse scattering observed in the electron diffraction patterns suggests a degree of short-range ordering. Both materials are oxide ion conductors. On thermal cycling, Bi0.88Nb0.12O1.62 exhibits a decrease in conductivity of approximately an order of magnitude due to partial transformation into the tetragonal phase, but still exhibits conductivity comparable to yttria-stabilised zirconia (YSZ). Ab-initio molecular dynamics simulations performed on Bi0.9375Nb0.0625O1.5625 show that oxide ion diffusion occurs by O2− jumps between edge- and corner-sharing OM4 groups (M=Bi, Nb) via tetrahedral □M4 and octahedral □M6 vacancies. © 2015 Elsevier Inc.en_AU
dc.identifier.citationTate, M. L., Hack, J., Kuang, X., McIntyre, G. J., Withers, R. L., Johnson, M. R., Evans, I. R. (2015). Bi1−xNbxO1.5+x (x=0.0625, 0.12) fast ion conductors: structures, stability and oxide ion migration pathways. Journal of Solid State Chemistry, 225, 383-390. doi:10.1016/j.jssc.2015.01.006en_AU
dc.identifier.issn0022-4596en_AU
dc.identifier.journaltitleJournal of Solid State Chemistryen_AU
dc.identifier.pagination383-390en_AU
dc.identifier.urihttps://doi.org/10.1016/j.jssc.2015.01.006en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/12583en_AU
dc.identifier.volume225en_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectOxidesen_AU
dc.subjectIonsen_AU
dc.subjectX-ray diffractionen_AU
dc.subjectNeutron diffractionen_AU
dc.subjectElectron diffractionen_AU
dc.subjectImpedanceen_AU
dc.subjectPhase transformationsen_AU
dc.titleBi1−xNbxO1.5+x (x=0.0625, 0.12) fast ion conductors: structures, stability and oxide ion migration pathwaysen_AU
dc.typeJournal Articleen_AU
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