Domain switching criterion for ferroelectric single crystals under uni-axial electromechanical loading

摘要

Domain switching is a long concerned topic in ferroelectrics while currently an accurate domain switching criterion (DSC) is still lacking. In this work, both 90 degrees and 180 degrees domain switching were carefully investigated in perfectly poled tetragonal BaTiO3 crystals. Pure 180 degrees domain switching was realized during bipolar electric loading, and pure 90 degrees switching was achieved by mechanical depoling and subsequent electric repoling. Results showed that the energy barrier for 180 degrees domain switching is considerably larger than that for 90 degrees switching. In addition, during 180 degrees domain switching, only slight hardening effect was observed while the 90 degrees switching process showed significant hardening behavior. Moreover, for 90 degrees domain switching, more energy was dissipated during mechanical depoling than that during electric repoling. Based on these experimental results, an incremental DSC was proposed for 90 degrees domain switching and the sharp DSC proposed by HWang et al. (1995) was adopted for 180 degrees switching. An electric field-stress-domain structure diagram of BaTiO3 crystal was then plotted to address the switching process. It is predicted that pseudoelasticity and large actuation strain can be realized in BaTiO3 crystals via reversible 90 degrees domain switching under uni-axial electromechanical loading. These predictions were further verified by subsequent testing, demonstrating the validity of the proposed DSC. (C) 2015 Elsevier Ltd. All rights reserved.