Screen-printed Pb(Zr,Ti)O3 thick films for ultrasonic medical imaging applications

Piezoelectric lead-zirconate-titanate, Pb(Zr,Ti)O-3 PZT-based thick films were processed by screen printing and firing on two different ceramic substrates: alumina and PZT. To lower the firing temperature of the PZT layers to 800-900degreesC the composition was modified with lead germanate (PGO) that forms a low-temperature liquid phase. Film thickness and porosity were estimated from SEM images, chemical composition was checked by EDS. Low-frequency dielectric measurements were also performed. A method based on a fitting process between experimental and theoretical impendance curves was used to obtain characteristics in thickness mode of these thick films. The measured properties of the thick films and the substrates were used to simulate single-element medical transducers with a modified K.L.M. model to evaluate their performance.