Microstructure and Stray Electric Fields at Surface Cracks in Ferroelectrics

This is the preprint of an article that will appear in the International Journal of Fracture (DOI: 10.1007/s10704-011-9670-2).

Microstructure and Stray Electric Fields at Surface Cracks in Ferroelectrics

by Lun Yang and Kaushik Dayal, Carnegie Mellon University

Abstract

Ferroelectric perovskites are widely used in transducer, memory and optical applications due to their attractive electromechanical and optical properties.  In these brittle materials, reliability and failure of devices is dominated by the behavior of cracks.  The electromechanical coupling causes cracks to interact strongly with both mechanical as well as electrical fields.  Additionally, cracks and domain patterns interact strongly with each other.  Hence, an understanding of the electromechanics of cracks requires an accounting of all these interactions.  In this work, we apply a real-space phase-field method to compute the stresses, domain patterns, and stray electric fields in the vicinity of a stationary crack, defined here as a geometric feature that causes large but bounded stress.  We investigate the effects of charge compensation on the crack face, crack orientation with respect to the crystal lattice, and applied far-field stress and electric fields.