Thick film sol gel PZT transducer using dip coating
A sol gel process has been used to develop a 30 μm thick PZT coating on a sapphire wafer. The sol gel film was removed and plated with platinum electrodes. The free-standing film had a free dielectric constant (εT) of 820, a thickness-mode coupling coefficient (kt) of 0.17, a speed of sound (c) of 3700 m/s, and an acoustic impedance (Z) of 28.9 MRayls. The film resonated at 62 MHz. These results were similar to KLM simulation results. A sol gel transducer was built by first backing the film with 2.2 mm thick silver epoxy. The transducer resonated at 32, 64, and 92 MHz. At 32 MHz, the transducer had a bandwidth of 40%. The insertion loss at 47 MHz was -66 dB. A 32 MHz image was constructed with this transducer by off-line processing of 40 rf-lines of data.
