Microstructural modeling of ferroelectric fracture

We present a microstructural model for ferroelectric ceramics based on the domain-level events occurring at the Curie transition point. Spontaneous po larization and strain are represented by discrete electric dipoles and forc e couples, respectively, affixed to an isotropic background medium. The fie lds of these point defects cause local domain interactions, and their orien tations are made to switch when an electromechanical energy threshold is ex ceeded. The model accurately reproduces the hysteresis curves, butterfly lo ops, and other fundamental aspects of typical ferroelectric material behavi or. In addition, by simulating domain switching near a crack tip, we predic t the previously unexplained decrease in apparent fracture toughness with a pplied voltage that has been observed in the laboratory. (C) 2001 Acta Mate rialia Inc. Published by Elsevier Science Ltd. All rights reserved.