Influence of crystal structure on crack propagation under cyclic electric loading in lead–zirconate–titanate

Crack propagation under cyclic electric loading was studied in two non-commercial compositions of lead–zirconate–titanate and compared to earlier results from a commercial composition. These materials were chosen to provide a well-defined variation in crystal structure, ranging from rhombohedral to tetragonal, including a composition from the morphotropic phase boundary. The results are presented in terms of crack propagation as a function of various electric load amplitudes. While the crack propagation rates were of the same order of magnitude in all three compositions, fracture occurred in an either trans- or intergranular manner with crack extension either in the form of a singular crack, a microcrack zone or with extensive secondary cracking. These differences in crack propagation are discussed in the context of different piezoelectric material properties.