Innovative fabrication of PZT pillar arrays by a colloidal approach

An innovative approach for fabricating pillar arrays for ultrasonic transducer applications is disclosed. It involves the preparation of concentrated piezoelectric lead zirconate titanate (PZT) suspensions in aqueous solutions of epoxy resin and its polymerization upon adding a polyamine based hardener. Zeta potential and rheological measurements revealed that 1 wt.% dispersant, 20 wt.% of epoxy resin and a hardener/epoxy resin ratio of 0.275 mL g−1, were the optimized contents to obtain strong PZT samples with high green strength (35.21 ± 0.39 MPa). Excellent ellipsoidal and semi-circle shaped pillar arrays presenting lateral dimensions lower than 10 μm and 100 μm height were successfully achieved. The organics burning off was conducted at 500 °C for 2 h at a heating rate of 1 °C min−1. Sintering was then carried out in the same heating cycle at 1200 °C for 1 h. The microstructures of the green and sintered ceramics were homogeneous and no large defects could be detected.