Domain switching induced fracture toughness variation in ferroelectrics

A theoretical model is proposed to investigate the toughness variation of a mono-domain ferroelectric induced by small-scale polarization switching. The toughness variation of poly-domain ferroelectrics is estimated by a Reuss-type approximation based on an orientation distribution function and the solution for mono-domain ferroelectrics. Anisotropic material properties and electromechanical coupling are considered in the present study. This differentiates the present model from the uncoupled models reported in the literature. Numerical results based on the present model show that a positive electric field impedes the propagation of an insulating crack perpendicular to the poling direction, while a negative field enhances it. This prediction is consistent with experimental observations. The anisotropy of fracture load of ferroelectrics is also examined by the present model. The effects of electromechanical coupling on toughness variation are highlighted.

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