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Comprehensive Linkage of Defect and Phase Equilibria Through Ferroelectric Transition Behavior in BaTiO 3 ‐Based Dielectrics: Part 2. Defect Modeling Under Low Oxygen Partial Pressure Conditions
Author(s) -
Lee Soonil,
Randall Clive A.,
Liu ZiKui
Publication year - 2008
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.1551-2916.2008.02372.x
Subject(s) - partial pressure , ferroelectricity , solubility , dielectric , materials science , phase (matter) , phase transition , oxygen , thermodynamics , vacancy defect , dissolution , analytical chemistry (journal) , chemistry , crystallography , organic chemistry , optoelectronics , physics
Defect and phase equilibria have been investigated through the ferroelectric phase transition behavior of pure and equilibrated nonstoichiometric BaTiO 3 powders. The paraelectric–ferroelectric phase transition temperature ( T C – T ) was found to vary systematically with materials fabricated with different Ba/Ti ratio ( g * ) and under various oxygen partial pressure () conditions. 1 The solubility regime, as determined through the T C – T variation, decreased with decreasing. 2 Determining the solubility limits and equilibrating the defect reactions at the solubility limits provide a direct approach to calculate the defect formation energies and provide data to test a new defect model for concurrent defect reactions of partial Schottky and reduction defects. A refined approach introduces a balanced equilibrium between the oxygen vacancy concentrations controlled by the partial Schottky and reduction reactions. In the limiting ambient cases the approach gives the expected results, and also fully explains the solubility trends under low 's. Universally, the theory supports all the experimental data over different temperatures and 's.