Fatigue crack growth in ferroelectrics under electrical loading

Fatigue crack growth is investigated in the polycrystalline ferroelectrics PZT-5H and PLZT 8/65/35 under electrical loading. The fatigue cracks exhibit features such as bifurcation and tunnelling, followed by crack arrest. The nature of the resulting damage differs in the two materials: in PZT-5H a narrow zone of intergranular cracks propagates across the specimen, wedging the crack surfaces apart. In PLZT 8/65/35 a broad microcracked band spreads across the specimen. The rate of crack growth is found to correlate well with the amplitude of electric displacement.