Effect of domain wall characteristics on material properties of lead zirconate titanate piezoelectric ceramics

To better understand the material properties of lead zirconate titanate (PZT) ceramics, the influence of domain wall characteristics on the electrical and mechanical properties of PZT ceramics has been investigated. To obtain various domain wall characteristics, the poling process was carried out with different patterns with respect to the PZT ceramic. The domain walls were aligned in the PZT ceramic in the direction perpendicular to the poling direction. Such domain wall characteristic produced different crack growth behaviours. The crack growth occurred mainly along the domain walls of {110} for a31 (crack growth direction perpendicular to the poling direction) because of the high stress concentration between the domain walls. In contrast, the crack propagated along both domain walls and grain boundaries for a33 (crack growth direction parallel to the poling direction), leading to high crack growth resistance and good mechanical properties. The fracture toughness KIC values for the PZT ceramics in the a31 and a33 directions were about 0·5 and 2·6 MPa m1/2 respectively. It also appeared that the domain walls collapsed when a number of poling processes are conducted along different directions. These PZT ceramics had high mechanical properties due to the low stress concentrations.