Electromechanical conversion efficiency of PZT films

Abstract

PZT thin films have been prepared by opposed-target RF-sputtering and laser ablation. The titanium to zirconium ratios were 60/40 and 48/52. The latter films were doped with Fe and Sr (PZT 8). The dielectric constant, polarization, and d33 coefficients were measured. A newly designed quadrature looper was used to acquire the polarization data and d33 was measured with a stabilized interferometer. The dielectric properties (ε and P) were slightly lower but comparable to bulk values. The best d33 was 7.7 (for a 60/40 film), a value which seems low. However, when the data are scaled to existing kp data, the measured value is in fact reasonable compared to bulk values. The d33 value for the 48/52 RF-sputtered films was significantly lower than what one would expect from dielectric data. PZT films as-deposited are oriented and exhibit piezoelectric activity before any poling treatment. The material was also difficult to depole.