Influence of dipole defects on polarization switching in the vicinity of a crack in relaxor ferroelectrics

Simulations of the polarization switching process near the tip of an edge crack in relaxor ferroelectrics subjected to external electric field have been carried out by employing the time-dependent Ginzburg-Landau theory and the phase-field method. The electric boundary conditions of the crack and the material are assumed to be impermeable and isotropic, respectively. The interaction between dipole defects and the crack and the influence of the dipole defect concentration on the switching process are discussed. The results obtained show that, in relaxor materials, polarization switching in the vicinity of the crack tip is suppressed, and the electric field distribution is not symmetric with respect to the crack surface. These results arise on account of the interaction between dipole defects and the crack and the inhomogeneous electric field induced by dipole defects. Moreover, the polarization switching rate and switching zone area decrease with an increase of dipole defect concentration.link_to_subscribed_fulltex