Strength of a PZT ceramic under different test conditions

Strength measurements were carried out in different poling states (unpoled, poled perpendicular, and parallel to the specimen length axis) under several externally applied electrical fields perpendicular to the specimen length axis and with different test procedures (bending and tensile tests). The main results were: (a) Polarisation parallel to the specimen length axis reduces the strength significantly, polarization in thickness direction showed small strength reduction only, (b) an electrical field directed normally to the length axis yields a significantly lower tensile strength compared with unpoled material, and (c) strength in bending and tensile tests exhibits strongly different results. The differences caused by the poling state and externally applied electric field are discussed in terms of orientation of domains ahead of natural cracks.