Selective interstitial hydration explains anomalous structural distortions and ionic conductivity in 6H-Ba4Ta2O9·1/2H2O

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dc.contributor.authorMarlton, FPen_AU
dc.contributor.authorBrown, AJen_AU
dc.contributor.authorSale, Men_AU
dc.contributor.authorMaljuk, Aen_AU
dc.contributor.authorBüchner, Ben_AU
dc.contributor.authorLewis, Wen_AU
dc.contributor.authorLuck, Ien_AU
dc.contributor.authorWood, MLen_AU
dc.contributor.authorMole, RAen_AU
dc.contributor.authorLing, CDen_AU
dc.date.accessioned2025-01-13T04:04:03Zen_AU
dc.date.available2025-01-13T04:04:03Zen_AU
dc.date.issued2023-04-11en_AU
dc.date.statistics2024-10-30en_AU
dc.description.abstractThe mixed ionic-electronic conductor 6H-Ba4Ta2O9 undergoes an unconventional symmetry-lowering lattice distortion when cooled below 1100 K in the presence of atmospheric water. This temperature corresponds to the onset of hydration, which reaches a maximum value for 6H-Ba4Ta2O9·1/2H2O below ∼500 K. We use a combination of diffraction, ab initio calculations, and spectroscopy to show that both processes are intimately linked. The presence of very large Ba2+ cations in octahedral interstitial sites (B sites of its hexagonal perovskite-type structure) forces the adjacent vacant octahedral interstitial sites also to expand, making room for them to incorporate hydration species with a total stoichiometric H2O in constrained and highly acidic environments, where they show structural and dynamic characteristics intermediate between those of covalent water molecules and discrete protons and hydroxide ions. This in turn destabilizes the structure so that it distorts on cooling in a way that cannot be explained by conventional symmetry-lowering mechanisms. The resulting synergistic hydration-distortion mechanism is, to the best of our knowledge, unique to close-packed ionic compounds. © 2023 American Chemical Society.en_AU
dc.description.sponsorshipThis work was supported by the Australian Research Council─Discovery Projects (DP190101862) and the Alexander von Humboldt Foundation (Friedrich Wilhelm Bessel Research Award). XRPD and TGA data were collected using facilities in Sydney Analytical, a core research facility at the University of Sydney.en_AU
dc.identifier.citationMarlton, F. P., Brown, A. J., Sale, M., Maljuk, A., Büchner, B., Lewis, W., Luck, I., Wood, M. L., Mole, R. A., & Ling, C. D. (2023). Selective interstitial hydration explains anomalous structural distortions and ionic conductivity in 6H-Ba4Ta2O9·1/2H2O. Chemistry of Materials, 35(7), 2740-2751. doi:10.1021/acs.chemmater.2c02653en_AU
dc.identifier.issn0897-4756en_AU
dc.identifier.issn1520-5002en_AU
dc.identifier.issue7en_AU
dc.identifier.journaltitleChemistry of Materialsen_AU
dc.identifier.pagination2740-2751en_AU
dc.identifier.urihttps://doi.org/10.1021/acs.chemmater.2c02653en_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15929en_AU
dc.identifier.volume35en_AU
dc.languageEnglishen_AU
dc.language.isoenen_AU
dc.publisherAmerican Chemical Societyen_AU
dc.subjectHydrationen_AU
dc.subjectIonic conductivityen_AU
dc.subjectHydrogenen_AU
dc.subjectTantalumen_AU
dc.subjectBariumen_AU
dc.subjectSpectroscopyen_AU
dc.subjectHydroxidesen_AU
dc.subjectCrystal latticesen_AU
dc.titleSelective interstitial hydration explains anomalous structural distortions and ionic conductivity in 6H-Ba4Ta2O9·1/2H2Oen_AU
dc.typeJournal Articleen_AU
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