Electric field induced cracking in ferroelectric ceramics

Ferroelectric ceramics are susceptible to fracture under high magnitude cyclic electric field. Flaws concentrate the electric field, inducing a large incompatible strain, and thereby a large stress. Stable growth of cracks with either conducting or insulating interiors is observed in 8/65/35 lanthanum lead zirconate titanate samples. Indentations on the electroded surface are filled with distilled water or a water-salt solution. Under cyclic electric field, tree like damage grows from the indented electrode. Indentations on the surfaces 90° to the electrodes are filled with silicone oil. This results in stable crack growth perpendicular to the cyclic electric field. Nonlinear fracture models are presented for both conducting and insulating cracks. Tensile stress intensity factors are predicted for both cases.