Structures, phase transitions, hydration, and ionic conductivity of Ba4Ta2O9
dc.contributor.author | Ling, CD | en_AU |
dc.contributor.author | Avdeev, M | en_AU |
dc.contributor.author | Kharton, VV | en_AU |
dc.contributor.author | Yaremchenko, AA | en_AU |
dc.contributor.author | Macquart, RB | en_AU |
dc.contributor.author | Hoelzel, M | en_AU |
dc.date.accessioned | 2010-03-23T05:48:26Z | en_AU |
dc.date.accessioned | 2010-04-30T05:04:06Z | en_AU |
dc.date.available | 2010-03-23T05:48:26Z | en_AU |
dc.date.available | 2010-04-30T05:04:06Z | en_AU |
dc.date.issued | 2010-01-26 | en_AU |
dc.date.statistics | 2010-01-26 | en_AU |
dc.description.abstract | Low-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 Society | en_AU |
dc.identifier.citation | Ling, 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/cm903170t | en_AU |
dc.identifier.govdoc | 1265 | en_AU |
dc.identifier.issn | 0897-4756 | en_AU |
dc.identifier.issue | 2 | en_AU |
dc.identifier.journaltitle | Chemistry of Materials | en_AU |
dc.identifier.pagination | 532-540 | en_AU |
dc.identifier.uri | http://dx.doi.org/10.1021/cm903170t | en_AU |
dc.identifier.uri | http://apo.ansto.gov.au/dspace/handle/10238/3001 | en_AU |
dc.identifier.volume | 22 | en_AU |
dc.language.iso | en | en_AU |
dc.publisher | American Chemical Society | en_AU |
dc.subject | Phase transformations | en_AU |
dc.subject | Hydration | en_AU |
dc.subject | Ionic conductivity | en_AU |
dc.subject | Perovskite | en_AU |
dc.subject | Tantalates | en_AU |
dc.subject | Annealing | en_AU |
dc.title | Structures, phase transitions, hydration, and ionic conductivity of Ba4Ta2O9 | en_AU |
dc.type | Journal Article | en_AU |
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