Premium
Comprehensive Linkage of Defect and Phase Equilibria through Ferroelectric Transition Behavior in BaTiO 3 ‐Based Dielectrics: Part 1. Defect Energies Under Ambient Air 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.1551-2916.2008.02297.x
Subject(s) - partial pressure , enthalpy , ferroelectricity , annealing (glass) , materials science , schottky diode , phase transition , dielectric , analytical chemistry (journal) , thermodynamics , chemistry , oxygen , metallurgy , optoelectronics , physics , organic chemistry , chromatography , diode
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 BaTiO 3 materials under highly controlled conditions to preserve the equilibrium conditions with respect to Ba/Ti ratio, annealing temperature ( T ), and oxygen partial pressure ( P O2 ), 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 TiO 2 partial‐Schottky defects (BaTi 1−δ O 3−2δ ) and the BaO partial‐Schottky defects (Ba 1−δ TiO 3−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 k B for the BaO partial‐Schottky defect, and 2.89±0.1 eV and 8.0±1.5 k B for the TiO 2 partial‐Schottky defects equilibrated under air annealing conditions.