THE JUMPING DIELECTRIC BREAKDOWN BEHAVIOR INDUCED BY CRACK PROPAGATION IN FERROELECTRIC MATERIALS: A PHASE FIELD STUDY [Keynote]

Ferroelectric materials often experience fracture and dielectric breakdown under large mechanical and/or electrical loadings. These two failure behaviours can affect each other and may lead to new phenomena. In the present study, a new type of jumping dielectric breakdown are predicted during the crack propagation in ferroelectric materials by using a phase field model with multiple order parameters. The driving force for the jumping dielectric breakdown induced by crack propagation is analysed based on the concept of configurational force. It is found that the jumping dielectric breakdown is attributed to the competition between the crack propagation and the breakdown initiation at the moving crack tip. The breakdown pattern is related to the polarization domain structure and thus greatly influenced by the applied electric field and the crack boundary conditions. Further, the jumping breakdown associated with possible mechanical degradation on the material can change the driving and resistant forces for the crack propagation. The present work not only suggests a novel dielectric breakdown behaviour during crack propagation but also provides new insights into the coupling failure of ferroelectric materials.
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