Structures, phase transitions, hydration, and ionic conductivity of Ba4Ta2O9

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dc.contributor.authorLing, CDen_AU
dc.contributor.authorAvdeev, Men_AU
dc.contributor.authorKharton, VVen_AU
dc.contributor.authorYaremchenko, AAen_AU
dc.contributor.authorMacquart, RBen_AU
dc.contributor.authorHoelzel, Men_AU
dc.date.accessioned2010-03-23T05:48:26Zen_AU
dc.date.accessioned2010-04-30T05:04:06Zen_AU
dc.date.available2010-03-23T05:48:26Zen_AU
dc.date.available2010-04-30T05:04:06Zen_AU
dc.date.issued2010-01-26en_AU
dc.date.statistics2010-01-26en_AU
dc.description.abstractLow-temperature α-Ba4Ta2O9 is isostructural with α-Ba4Nb2O9 (Sr4Ru2O9 type), and it undergoes a reconstructive phase transition at approximately the same temperature (1400 K) to a γ form that can easily be quenched to room temperature. However, the γ forms of the two compounds are completely different. Whereas γ-Ba4Nb2O9 represents a unique structure type, γ-Ba4Ta2O9 adopts a more conventional 6H-perovskite type. The α→γ transition is virtually irreversible in the tantalate, unlike the niobate, which can be converted back to the α form by annealing slightly below the transition temperature. Quenched γ-Ba4Ta2O9 is highly strained due to the extreme size mismatch between Ba2+ (1.35 Å) and Ta5+ (0.64 Å) cations in perovskite B-sites, and undergoes a series of symmetry-lowering distortions from P63/mmc→P63/m→P21/c; the second of these transitions has not previously been observed in a 6H perovskite. Below 950 K, both α-Ba4Ta2O9 and γ-Ba4Ta2O9 hydrate to a greater extent than the corresponding phases of Ba4Nb2O9. Both hydrated forms show significant mixed protonic and oxide ionic conductivity, and electronic conductivity upon dehydration. © 2010, American Chemical Societyen_AU
dc.identifier.citationLing, C. D., Avdeev, M., Kharton, V. V., Yaremchenko, A. A., Macquart, R. B., & Hoelzel, M. (2010). Structures, phase transitions, hydration, and ionic conductivity of Ba4Ta2O9. Chemistry of Materials, 22(2), 532-540. doi:10.1021/cm903170ten_AU
dc.identifier.govdoc1265en_AU
dc.identifier.issn0897-4756en_AU
dc.identifier.issue2en_AU
dc.identifier.journaltitleChemistry of Materialsen_AU
dc.identifier.pagination532-540en_AU
dc.identifier.urihttp://dx.doi.org/10.1021/cm903170ten_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/3001en_AU
dc.identifier.volume22en_AU
dc.language.isoenen_AU
dc.publisherAmerican Chemical Societyen_AU
dc.subjectPhase transformationsen_AU
dc.subjectHydrationen_AU
dc.subjectIonic conductivityen_AU
dc.subjectPerovskiteen_AU
dc.subjectTantalatesen_AU
dc.subjectAnnealingen_AU
dc.titleStructures, phase transitions, hydration, and ionic conductivity of Ba4Ta2O9en_AU
dc.typeJournal Articleen_AU
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