PFM investigation of stress induced ferroelastic switching in piezoelectric bulk ceramics

Stress induced ferroelastic switching may represent an efficient toughening mechanism in piezoelectric-ferroelectric ceramics. During the crack propagation, the high tensional stresses at the crack tip can be partially released by the reorientation of 90 degree domains from along to perpendicular to the propagation direction. Compared to the phase transformation approach (inclusion of zirconia particles in the metastable tetragonal phase) this mechanism is not expected to reduce the piezoelectric properties of the material. In this work, we first present a method, which enables controlled crack growth in piezoelectric ceramics on a PFM instrument in order to observe the exact evolution of the ferroelastic domains and then preliminary observations of the ferroelectric domain patterns around a crack tip obtained by indentation are discussed. The observed domain structure in the vicinity of the crack tip shows similarity with the domain patters reported in other works, which include modeling and XRD.