Bending strength of a PZT ceramic under electric fields

Bending strength measurements were carried out in different poling states (unpoled, poled perpendicular and parallel to the specimen length axis) under various externally applied electric fields perpendicular to the specimen length axis. The main results were: (a) polarisation parallel to the specimen length axis significantly reduces strength, polarisation in the direction of thickness produces minor strength reductions only, (b) an electric field directed normal to the length axis reduces the strength. The differences caused by the poling state are discussed in terms of orientation of domains in front of natural cracks for the case of a disappearing electric field.