Piezoelectric strain in lead zirconate titante ceramics as a function of electric field, frequency, and dc bias

We have investigated the electromechanical response of piezoelectric ceramics as a function of the amplitude and frequency of large electric fields and studied the effects of dc bias fields. In order to characterize the materials under these conditions, a ZMI 2000 laser interferometer system from Zygo Corp. has been installed and modified to directly measure the strains of ferroelectric ceramics. This system uses a heterodyne detection technique and has the advantages of phase detection, wide bandwidth, high stability, and easy optical alignment. Our experiment has been used to determine the strain of lead zirconate titanate (PZT) ceramics as a function of electric fields and as a function of frequency in the low frequency range. From these measurements the piezoelectric coefficients d33, d31, and d15 have been determined as a function of applied field and frequency. In addition the dependence of the piezoelectric coefficients under an applied dc bias field has been studied under quasistatic and under resonance conditions. Some of our measurements have provided evidence of the time dependence of the piezoelectric response. Results on a range of soft and hard PZT ceramics manufactured by EDO Corp. are presented. These results are discussed within the context of extrinsic contributions to the piezoelectric response