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Ordering/Displacive Phase Transformations in Ca4Nb2O9



Igor Levin, Leonid A. Bendersky, Robert S. Roth, Terrell A. Vanderah


Four Ca4Nb2O9=Ca(Ca1/3Nb2/3)O3 polymorphs based on ABO3 perovskite-like structure were identified. These polymorphs feature three different arrangements of Ca/Nb cations on B-sites of perovskite. In three of the polymorphs, cation ordering is combined with octahedral tilting. Symmetry relations between Ca 4Nb2O9 polymorphs were analyzed in terms of group/subgroups relations, separating the effects of octahedral tilting and cation ordering on symmetry changes. The types of domains, resulting from tilting and ordering phase transitions between different Ca 4Nb2O9 structures, and their spatial hierarchy expected from the formal symmetry considerations were related to those experimentally observed by transmission electron microscopy (TEM).
Journal of the Japan Institute of Metals


Ca<sub>4</sub>Nb<sub>2</sub>O<sub>9</sub>, octahedral tilting, ordering, perovskite, phase transitions, TEM


Levin, I. , Bendersky, L. , Roth, R. and Vanderah, T. (1999), Ordering/Displacive Phase Transformations in Ca<sub>4</sub>Nb<sub>2</sub>O<sub>9</sub>, Journal of the Japan Institute of Metals (Accessed May 26, 2024)


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Created December 17, 1999, Updated February 19, 2017