PZT thick films obtained by electrophoretic deposition (EPD) process for high frequency focused transducers

Piezoelectric lead zirconate titanate (PZT) thick films were prepared on flat and curved substrates by electrophoretic deposition (EPD) process. PZT and PbO particles were dispersed in ethanol to obtain a stable suspension and deposited on flat alumina at constant current density of 1.56 mA/cm² for 90 seconds and on curved unpoled porous PZT substrates at constant current density of 3.57 mA/cm² for 60 seconds. The deposits were sintered at 950°C for 2 hours in a PbO-controlled atmosphere. The thickness of the PZT film on curved substrate is 30 μm and the porosity is 17 %. An effective thickness coupling factor of around 50 % and a dielectric constant at constant strain of 320 were measured on flat substrate. An operating high frequency single element transducer with a center frequency close to 30 MHz was fabricated and characterized. The transducer was integrated into an echographic imaging system. In-vivo skin images were illustrated to show the great potential of EPD method for the fabrication of high frequency transducers for medical applications.