Dynamic Observation of Crack Propagation in Piezoelectric Multilayer Actuators

Crack propagation in multilayer piezoelectric actuators made of Pb((Ni_1/3Nb_2/3), Ti, Zr)O₃ ceramics with an interdigital electrode configuration was observed dynamically under an applied cyclic electric field using charge coupled device microscopy. The crack was observed only under a high electric field, and it healed under zero field. The crack was initiated at the internal electrode edge and propagated from the electrode edge in three directions. The electric‐field‐induced displacement was measured simultaneously with the propagation. The displacement of the multilayer actuator became gradually smaller and asymmetric with respect to the sign of the field with increased driving cycle.