Comprehensive linkage of defect and phase equilibria through ferroelectric transition behavior in BaTiO3-based dielectrics: Part 1. Defect energies under ambient air conditions

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Abstract

Defect and phase equilibria have been investigated via the ferroelectric phase transition behavior of pure and equilibrated nonstoichiometric BaTiO 3 powder samples. Through fabricating the BaTiO3 materials under highly controlled conditions to preserve the equilibrium conditions with respect to Ba/Ti ratio, annealing temperature (T), and oxygen partial pressure (PO2), systematic variations in the phase transition temperature can be noted with respect to Ba/Ti ratio and T. From the data extracted, we can then determine solubility limits. Equilibrating the defect reactions at the solubility limits provides a direct approach to identify and calculate the defect energetics. The phase transition temperature decreased with increasing concentration of the TiO2 partial-Schottky defects (BaTi 1-δO3-2δ) and the BaO partial-Schottky defects (Ba1-δTiO3-δ), and showed discontinuous changes in the two-phase region. The formation enthalpy and entropy for the partial-Schottky defect reactions was evaluated to be 2.32±0.1 eV and 10.15±0.7 kB for the BaO partial-Schottky defect, and 2.89±0.1 eV and 8.0±1.5 kB for the TiO2 partial-Schottky defects equilibrated under air annealing conditions.

Original languageEnglish (US)
Pages (from-to)1748-1752
Number of pages5
JournalJournal of the American Ceramic Society
Volume91
Issue number6
DOIs
StatePublished - Jun 1 2008

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All Science Journal Classification (ASJC) codes

  • Ceramics and Composites
  • Materials Chemistry

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