Electrical creep around a circular hole in PLZT 8/65/35

The strain–birefringence correlation was exploited to study the local behaviour near a circular hole in unpoled PLZT 8/65/35 under electric field below than the coercive field. The observed birefringence contours near the hole show a spatial distribution and time dependence. Due to the enhancement of electric field near the hole, the polarization creep rate is greatly increased. The evolution of the local principal strain difference with time and position in the sample is quantified. Overall, an accelerated poling effect is found in comparison with the behaviour under uniform field. This appears to be due to inhomogeneous field distribution which initiates polarization switching in areas of locally enhanced electric field. The presence of the hole promotes a nearly linear growth in average polarization with time, despite the strongly nonlinear response of the parent material. The results indicate that insulating porosity can strongly affect the switching behaviour and coercivity of ferroelectric ceramics.