QUANTITATIVE-EVALUATION OF EXTRINSIC CONTRIBUTION TO PIEZOELECTRIC COEFFICIENT D(33) IN FERROELECTRIC PZT CERAMICS

The contribution of 90-degrees domain wall motion to the piezoelectric coefficient d33 in ferroelectric PZT ceramics has been evaluated quan titatively by a simple model. The microstructures of PZT ceramics have also been considered through the evaluation process. In order to avoi d some formidable and somewhat ambiguous calculations involved and als o in order to offer a clear physical Picture of the domain contributio n to the piezoelectric coefficient d33 in ferroelectric ceramics, we h ave introduced a new concept of the effective number of domain walls i n the quantitative evaluation process which reflects the magnitude of domain wall density in ceramics. The obtained calculation result, DELT Ad33 = 219.4 X 10(-12) m/V, supports the measured data and also is inh erently plausible in terms of the contribution of domain wall motion t o the electromechanical properties of ferroelectric ceramics.