Crack tip domain switching in normal and relaxor ferroelectrics subjected to mechanical and electric loading

Abstract

Two-dimensional phase field simulations of domain switching in the crack tip vicinity of a crack embedded in a normal ferroelectric single crystal, which was subjected to mechanical and electric loading, have been carried out. The domain switching zones induced by the mechanical and electric loading were plotted. The stress field near the crack tip was also plotted to investigate the effect of domain switching on crack. The obtained domain switching zones are in good agreement with the existing theoretical predictions and experimental observations. The stress field obtained showed that a positive electric field inhibited while a negative field promoted crack propagation. Simulations of the polarization switching process near the tip of a crack in relaxor ferroelectrics subjected to external electric field have also been carried out. The interaction between the dipole defects and crack, and the influence of the dipole defect concentration density on the switching process has been discussed. The results obtained showed that in relaxor materials the polarization switching in the vicinity of the crack tip was suppressed, and the electric field distribution was not symmetric to the crack surface. These were due to the interaction between the dipole defects and crack, and the inhomogeneous electric field induced by dipole defects. Moreover, the polarization switching rate and switching zone area decreased with the increase of dipole defect concentration density.