Experimental studies on the non-linear ferroelectric and ferroelastic properties of piezoceramics

We summarize some of the experimental work on the constitutive behaviour of Soft-PZT piezoceramics carried out at the Research Center Karlsruhe during the recent years. In particular, multi-axial, non-proportional polarization rotation tests are presented for a commercial soft PZT material under purely electric field loading. In addition to the polarization measurement along the field loading direction, the normal strain responses in all three coordinate directions were monitored simultaneously using a strain gauge technique. Based on a series of polarization and strain versus electric field curves, switching (domain reorientation threshold) surfaces were constructed in the bi-axial electric field plane using the conventional offset method. The experimental data can be used to examine the existing switching criteria in phenomenological models for the non-linear constitutive behavior of piezoceramics.