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

Domain polarization switch near the tip of a ¯aw plays a critical role on the fracture of poled ferroelectric ceramics under mechanical loading. Small scale 90 switching model is adopted with domain switch based on the switching released work. The model focuses on the in¯uence on the stress intensity factor by 90 switching. Di€erent 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 di€erences in isotropic and anisotropic indentation tests can be explained qualitatively