Exploration of Non-MPB PZT Compositions for High Piezoelectric Voltage Sensitive 0-3 Composites

Abstract

Piezoelectric composites provide an opportunity to make robust piezoelectric sensors. These materials are based on piezoelectric ceramic powders or particles, which are dispersed in a polymer matrix. In most cases, piezoelectric composites use the same ceramic compositions as the ones used in piezoelectric ceramics. These compositions consist of lead zirconium titanate (PZT) with a composition close to the morphotropic phase boundary (MPB). This research work focuses on exploring the performance of non-MPB compositions of PZT ceramic particles in order to obtain high voltage sensitive 0-3 PZT-Epoxy composites. The PZT ceramic compositions (PbNb0.01[ZrxTi(1-x)]O3), ranging from pure tetragonal lead titanate (x=0) to rhombohedral (x=0.80) were prepared using the mixed oxide method. These ceramic particles were characterized using XRD, SEM and particle size analyser and were used to prepare both sintered ceramics and 0-3 PZT-epoxy composites. The effect of the ceramic filler composition on the dielectric and piezoelectric properties of the PZT-Epoxy composites was investigated. Unlike PZT ceramics, the best piezoelectric properties were not observed in the MPB-based composites but in the pure tetragonal phase. It was observed that the dielectric constant of the ceramic particles had minimal influence on the effective dielectric constant (?r) and the piezoelectric charge constant (d33) of the piezoelectric composite due to the depolarization effect of the high dielectric filler materials. The experimentally determined values of the dielectric and piezoelectric properties of the piezoelectric composites were validated using analytical models. The influence of electric fatigue on the polarization of the PbTiO3 (PT) and morphotropic phase boundary (MPB) based composites were also examined. Finally, a material selection criterion was proposed in order to develop piezoelectric composites with high voltage sensitivity. This general material selection criterion is not limited to PZT based ceramics but is also applicable to lead-free ceramic filler materials. Thus, the current research work paves the way for the development of environmental friendly lead-free piezoelectric composites devices with enhanced sensory properties.