Measurements of Complex Piezoelectric d33 Constant in Ferroelectric Ceramics under High Electric Field Driving

A measurement system has been designed and constructed which is capable of automatic data collection for complex piezoelectric d 33 constant (amplitude and phase), field-induced polarization and switching current under high electric field driving in ferroelectric materials. The system is based on the direct piezoelectric effect and d 33 constant can be measured down to about 10 pC/N. Using this system, low and high electric field piezoelectric responses were examined in soft lead zirconate titanate (PZT) ceramics by comparing the data with the total polarization and strain changes. At a low a.c. electric field, the observed complex piezoelectric d 33 constant measured by the direct piezoelectric method is equal to the values measured by the converse piezoelectric method, and the field-induced strain is fully accounted for the complex piezoelectric d 33 constant. At a high electric field, however, the amount of total strain becomes larger than the estimated strain by integrating d 33 in terms of electric field. The contribution of irreversible domain wall motion to the total strain change was found to approach 51.5% at the electric field strength of +1400 V/mm. The newly developed system can quantitatively determine the lattice motion and reversible domain wall motion-induced strain component in the total strain response under the high electric field driving in piezoelectric ceramics.