Smart thin-film piezoelectric composite sensors based on high lead zirconate titanate content

Piezoelectric composites are hybrid materials primarily consisting of polymer matrices and micro-sized particles of ferroelectric ceramic. While incorporating high-fraction ceramic particles into composites is indispensable to meet the ever increasing requirement of sensitivity, it is a great challenge to achieve such a high concentration due to processing difficulties. In this study, we developed piezoelectric composites of 0-3 geometry containing 95 wt% (∼73 vol%) lead zirconate titanate particles by modifying the surface of lead zirconate titanate particles with isophorone diisocyanate and polyoxyalkyleneamine (J2000) and compounding them with epoxy resin. The functional groups of J2000 molecules covalently grafted onto the particle surface can react with the matrix, thus creating a robust linkage between the matrix and the particles. This improved the particle dispersion and the interface, enabling the development of a superior composite film with high lead zirconate titanate fractions. Modified piezocomposites can save up to 75% poling time at 75% lower voltage in comparison with the unmodified sample as well as previous studies. The remarkable improvement is indebted to the two-stage interface modification process and the layer-by-layer fabrication method.