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Factors Limiting Equilibrium in Fabricating a Simple Ferroelectric Oxide: BaTiO 3
Author(s) -
Lee Soonil,
Randall Clive A.,
Liu ZiKui
Publication year - 2009
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.1551-2916.2008.02859.x
Subject(s) - ferroelectricity , materials science , phase transition , nucleation , quenching (fluorescence) , dielectric , thermodynamic equilibrium , thermodynamics , condensed matter physics , phase (matter) , chemistry , optics , optoelectronics , physics , organic chemistry , fluorescence
This paper demonstrates a number of features that can contribute to BaTiO 3 being perturbed from an equilibrium condition. The BaTiO 3 synthesis study was conducted with a modified citrate process, but the kinetic aspects limiting the equilibrium state are believed to be general to any processing route. The equilibrium conditions can be determined through a detailed analysis of the paraelectric–ferroelectric phase transition data measured by differential scanning calorimeter. Broadened and multiple latent heat peaks are found indicating a distribution of slightly different ferroelectric transition temperatures for nonequilibrated BaTiO 3 materials. A number of factors have been found that limit the equilibrium conditions, and these include time at formation conditions of temperature and oxygen partial pressure, a second phase BaCO 3 , and the rapid nucleation of a BaTi 2 O 5 phase on quenching to room temperature from temperatures in and around 1250°C. All of these nonequilibrium factors that occurs at high temperature lead to the ferroelectric phase transition having multiple phase transitions, owing to regions of the BaTiO 3 having different partial Schottky concentrations.