Micromechanics simulation of spontaneous polarization in ferroelectric crystals

Authors
Citation
Wf. Li et Gj. Weng, Micromechanics simulation of spontaneous polarization in ferroelectric crystals, J APPL PHYS, 90(5), 2001, pp. 2484-2491
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF APPLIED PHYSICS
ISSN journal
0021-8979 → ACNP
Volume
90
Issue
5
Year of publication
2001
Pages
2484 - 2491
Database
ISI
SICI code
0021-8979(20010901)90:5<2484:MSOSPI>2.0.ZU;2-M
Abstract
Based on a modified equivalent inclusion method and a thermodynamic theory, a micromechanics model is developed to predict the evolution of internal s tress and the effects of microstructural features (i.e., new domain concent ration and porosity) and the external hydrostatic pressure on the transitio n temperature for single crystal ferroelectric ceramics upon cooling. Durin g the cubic-to-tetragonal transition the material is a composite, with an i nternal stress due to phase transformation. Consideration of the thermodyna mic driving force and resistance force leads to a kinetic equation that pro vides the volume concentration of new domains at a given level of temperatu re and applied stress. This new domain concentration results in an increase of overall electric polarization. Numerical calculations using the propert ies of BaTiO3 indicate that internal stress in the parent cubic phase conti nues to develop during spontaneous polarization, and that increased porosit y greatly facilitates the transition process. Hydrostatic pressure provides an additional contribution to the Gibbs free energy of the system and also can increase the transition temperature. Its effect generally follows the Clausius-Clapeyron equation, but weak nonlinearity is found at very high pr essure. This departure is attributed to the change in heat capacity during the cubic-tetragonal transition. A comparison with some observed data for t he evolution of overall polarization of a BaTiO3 crystal serves to support the rationality of the model. (C) 2001 American Institute of Physics.