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Formation and Stability of Ferroelectric BaTi 2 O 5
Author(s) -
Zhu Na,
West Anthony R.
Publication year - 2010
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2009.03393.x
Subject(s) - nucleation , decomposition , thermodynamics , metastability , atmospheric temperature range , phase diagram , kinetic energy , chemistry , chemical stability , phase (matter) , materials science , quantum mechanics , physics , organic chemistry
BaTi 2 O 5 (BT 2 ) is thermodynamically stable over a very narrow temperature range between 1220° and 1230°C: a modification to the BaO–TiO 2 phase diagram is proposed. This thermodynamic stability was shown by constructing a time–temperature transformation diagram for the decomposition of BT 2 . Once formed, BT 2 appears to be stable indefinitely at 1220°–1230°C; at higher temperatures, the decomposition rate increases with temperature; at lower temperatures, the decomposition rate increases with decreasing temperature and passes through a maximum at ∼1200°C; below ∼1150°C, BT 2 has long‐lived kinetic stability. Kinetic considerations show a nucleation and growth mechanism for decomposition, with a nucleation induction period that is very temperature dependent. BT 2 can be prepared by various routes, including solid‐state reaction of oxides below ∼1100°C; because it is metastable at all temperatures other than 1220°–1230°C, its formation is an example of Ostwald's rule of successive reactions. Discrepancies in the literature concerning the reported stability range of BT 2 can be explained by the complex dependence on temperature and time of both its formation and decomposition, for both of which, the nucleation stage is rate limiting.