The influence of processing parameters on piezoelectric and dielectric properties of dome-shaped composite PZT-epoxy actuators

Thick film dome-shaped composite PZT-epoxy structures have been fabricated using a modified sol gel and spin coating technique. Processing parameters and polarization technique (Corona versus contact polarization) have been studied to elucidate their influence on piezoelectric and dielectric properties. The volume fraction of PZT was varied from 0.0 to 0.7 and the highest values for the longitudinal piezoelectric coefficient, effective dielectric constant (@1kHz) and dielectric loss (@1kHz), were 11.1 pC/N, 28.7 and 0.004 respectively for the PZT volume fraction equal to 0.7. The piezoelectric strain coefficient for this dome structure was 7 times higher than previously reported values for a composite PZT-epoxy dome structure of similar structure and composition. The sample morphology was examined with the aid of scanning electron microscopy (SEM) images. The piezoelectric strain coefficients, capacitance, and effective dielectric constant increased with increasing PZT volume fraction, in addition to the surface roughness. Samples that were Corona poled facilitated higher polarization voltages (45 kV/mm and 70 kV/mm) and resulted in higher values of piezoelectric strain coefficients. Investigation of composite structures such as these will advance the development of curved and hemispherical piezoelectric actuators with enhanced displacement and mechanical properties.