Investigation of domain switching of PZT and KNN - based ceramics

As known, ferroelectric ceramics generate strain and stress against an external clamping at high electric fields, which is used in actuator applications. To understand this response quantitatively bulk samples of commercial PZT and in-house produced KNN ceramics were investigated in model experiments. On bulk samples, the typical non-linear polarization hysteresis is found in a wide temperature range TN...TC. Below the characteristic temperature TN polarization reversal is suppressed, which is explained by domain wall pinning. The applied energy by the external electric field is too low to overcome the critical pinning energy barrier U/kT. Experimental results of measured threshold electric field and energy for domain switching are given for Sonox P 53 and KNN based ceramics.