Innovations in piezoelectric materials for ultrasound transducers

Piezoelectric materials lie at the heart of ultrasonic transducers. Recent advances in materials development include submicron piezoelectric ceramics (PZT) which lead to improvements in feature size, i.e. aspect ratio, element width, etc., for linear arrays and high frequency transducers (> 100 MHz). In contrast to fine grain ceramics, single crystal materials based on Relaxor-PT ferroelectrics offer electromechanical coupling coefficients > 90% with a range of dielectric permittivity (100s to 1000s) allowing flexibility in transducer engineering in regard to electrical impedance matching. Using KLM modeling, very high bandwidth performance > 120% is projected. Specific examples of high frequency 1-3 composites and 1-D linear array transducers fabricated from new piezoelectric materials, including sol-gel derived PZT fibers, are presented.