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

Abstract

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.

Residual stress effects on piezoelectric response of sol-gel derived lead zirconate titanate thin films

“…Thus, the extent and onset of this degradation in ferroelectric response are dependent on the magnitude of the applied ac ripple. A similar effect is observed for d 33 estimates obtained from the instantaneous derivative of the displacement-voltage curves in the large applied ac field case. This d 33 value reaches a peak in the constant slope region and then progressively decreases as more voltage is applied.…”

“…A similar effect is observed for d 33 estimates obtained from the instantaneous derivative of the displacement-voltage curves in the large applied ac field case. This d 33 value reaches a peak in the constant slope region and then progressively decreases as more voltage is applied. The films appear to reach a saturation point, after which all domain switching has occurred and intrinsic dipole stretching has reached its limits.…”

“…However, Table I shows that a noticeable difference exists in the d 33 value measured on the same specimen under different driving conditions. For the 350 and 500 nm specimens, there is a ϳ30% decrease in measured d 33 for the dc bias case, while a similar 12% decrease is observed for the 190 nm sample. The origin of this difference is likely a combination of the active mechanisms that contribute to the piezoelectric response and the manner in which d 33 is calculated for each of the respective driving cases.…”

“…As expected, higher displacements are observed for positive driving fields, in accordance with the film expanding away from the substrate. Less displacement amplitudes, and thus lower d 33 values, are measured in the direction of negatively applied fields. The lower displacement is attributed to the constraint of the substrate while the film is being compressed.…”

“…This phenomenon is also observed in soft PZT bulk samples and attributed to domain pinning induced by the high dc field. 33 In this scenario, dipoles are in a highly stretched configuration as the dc bias field becomes larger. Continued increases in the applied dc field potentially lead to the domains becoming locked in this stressed arrangement and unable to respond to the small voltage fluctuations provided by the overlapping ac field.…”