Piezoelectric Coefficients of PZT Thin Films

Longitudinal piezoelectric coefficient (d 33 ) and transverse piezoelectric coefficient (e 31 ) of sol-gel derived lead zirconate titanate (PZT) thin films have been measured. d 33 was measured based on the converse piezoelectric effect using a single beam laser interferometer. Bending of the substrate caused by surface displacement of the PZT film was eliminated by clamping the substrate tightly to a large and rigid platform. e 31 was measured based on the direct piezoelectric effect using a simple experimental setup. In the measurement, a rectangular PZT film sample (with substrate) was bent in such a way that a longitudinal strain was generated along the length of the sample. The induced current was measured using a lock-in amplifier. This method does not require any expensive equipment and special techniques for preparing the sample. Effects of lead loss and annealing temperature on the piezoelectric properties have been studied.