|
Home |
| Browse | |
|
|
Communities & Collections |
|
|
Issue Date |
|
|
Author |
|
|
Title |
|
|
Subject |
| Sign on to: | |
|
|
Receive email updates |
|
|
My APO authorized users |
|
|
Edit Profile |
|
|
|
|
|
About DSpace |
ANSTO Publications Online >
Journal Publications >
Journal Articles >
Please use this identifier to cite or link to this item:
http://apo.ansto.gov.au/dspace/handle/10238/1789
|
| Title: | Structures, phase transitions, hydration, and ionic conductivity of Ba4Nb2O9. |
| Authors: | Ling, CD Avdeev, M Kutteh, R Kharton, VV Yaremchenko, AA Fialkova, S Sharma, N Macquart, RB Hoelzel, M Gutmann, MJ |
| Keywords: | Hydration Ionic Conductivity Phase Transformations Niobates Barium Molecular Structure |
| Issue Date: | 25-Aug-2009 |
| Publisher: | American Chemical Society |
| Citation: | Ling, C. D., Avdeev, M., Kutteh, R., Kharton, V. V., Yaremchenko, A. A., Fialkova, S., et al. (2009). Structures, phase transitions, hydration, and ionic conductivity of Ba4Nb2O9. Chemistry of Materials, 21(16), 3853-3864. |
| Abstract: | Ba4Nb2O9 is shown to have two basic polymorphs: a high-temperature γ phase, which represents an entirely new structure typed and a low-temperature (x phase, which has the rare Sr4Ru2O9 structure type. The phases are separated by a reconstructive phase transition at similar to 1370 K, the kinetics of which are sufficiently slow that the γ phase can easily be quenched to room temperature. Below similar to 950 K, both (α and γ phases absorb significant amounts of water. In the case of the γ phase, protons from absorbed water occupy ordered positions in the structure, giving rise to a stoichiometric phase γ-III-Ba4Nb2O9.1/3H(2)O at room temperature. γ-III-Ba4Nb2O9-1/3H(2)O partially dehydrates, at similar to 760 K to give another stoichiometric phase γ-II-Ba4Nb2O9.1/3H(2)O, which completely dehydrates at similar to 950 K to γ-I- Ba4Nb2O9. The hydrated γ phases exhibit faster protonic and oxide ionic transport than the hydrated (x phases because of the presence in the γ phases of 2D layers containing Nb5+ cations with unusually low oxygen coordination numbers (4 or 5) separated by discrete OH groups. Hydration appears to play an important role in stabilizing the γ phases at low temperatures, with the γ -> α transition oil reheating a quenched sample occurring at higher temperatures in humid atmospheres. © 2009, American Chemical Society |
| URI: | http://dx.doi.org/10.1021/cm901644e http://apo.ansto.gov.au/dspace/handle/10238/1789 |
| ISSN: | 0897-4756 |
| Appears in Collections: | Journal Articles |
Files in This Item: There are no files associated with this item. |
Items in APO are protected by copyright, with all rights reserved, unless otherwise indicated.
|
DSpace Software Copyright © 2002-2010 Duraspace - Feedback |