Critical role of domain switching on the fracture toughness of poled ferroelectrics

Domain polarization switch near the tip of a flaw plays a critical role on the fracture of poled ferroelectric ceramics under mechanical loading. Small scale 90 degrees switching model is adopted with domain switch based on the switching released work. The model focuses on the influence on the stress intensity factor by 90 degrees switching. Different poling directions are explored. The case of out-of-plane poling is analyzed in detail, whose result indicates appreciable shielding on the SIF for crack growing in steady state. This prediction is supported qualitatively by Vickers indents data of polycrystalline and single-crystalline ferroelectrics in which the differences in isotropic and anisotropic indentation tests can be explained qualitatively. (C) 2001 Elsevier Science Ltd. All rights reserved.