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Thermodynamic Stability and Mechanisms of Formation and Decomposition of Perovskite Pb(Zn 1/3 Nb 2/3 )O 3 Prepared by the PbO Flux Method
Author(s) -
Jang Hyun M.,
Oh S. Hoon,
Moon Jong H.
Publication year - 1992
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.1151-2916.1992.tb05446.x
Subject(s) - pyrochlore , perovskite (structure) , decomposition , materials science , activation energy , phase (matter) , atmospheric temperature range , mineralogy , inorganic chemistry , chemistry , crystallography , thermodynamics , physics , organic chemistry
The mechanisms of formation and decomposition of the ferroelectric perovskite PZN [Pb(Zn 1/3 Nb 2/3 )O 3 ] were examined. The formation of perovskite PZN from the excess molten PbO environment is characterized by an inititial rapid formation of pyrochlore phase, followed by a subsequent reaction between the intermediate pyrochlore phase, ZnO, and liquid PbO to produce perovskite phase. The pure perovskite PZN crystal prepared by the PbO flux method is thermodynamically unstable over a wide range of temperature (600° to 1400°C), yielding pyrochlore phase and PbO as the decomposition products. The decomposition reaction of perovskite PZN proceeded uniformly with a spatial homogeneity throughout the specimen. The estimated activation energy of the decomposition reaction is approximatley 18 kcal/mol.