Electric field induced fracture mechanism and aging of piezoelectric behavior in Pb(MgNb)O3–Pb(ZrTi)O3 multilayer ceramic actuators

Electrical aging and mechanical fracture behavior of 0.2(PbMg1/3Nb2/3O3)–0.8(PbZr0.475Ti0.525O3) multilayer ceramic actuators have been investigated by applying both bipolar and unipolar voltages for unpoled and poled actuator, respectively. After 8.7×107 cycles of 2 kV/mm bipolar voltage, unpoled multilayer ceramic actuator had distorted shape of P–E hysteresis loops. Effective electromechanical coupling coefficient keff of poled actuator was calculated by considering resonant frequency and anti-resonant frequency. Pseudo-peizoelectric constant, d33, was also estimated through the strain versus electric field characteristics. From the SEM analysis, crack growth of multilayer ceramic actuator was clearly observed along the boundary between electrode and inactive region. The main reason for destruction of 0.2(PbMg1/3Nb2/3O3)–0.8(PbZr0.475Ti0.525O3) multilayer ceramic actuators was mechanical tensile stress coming from both actuation of, d33, mode and motion due to Poisson ratio.