Recent Advances in Piezoelectric Materials for Electromechanical Transducer Applications

Ferroelectricity has made a huge impact on science and technology since Joseph Valasek (then a Ph.D. student at the University of Minnesota) discovered it in 1920, a little longer than 100 years ago. Whereas Dr. Valasek's original research was motivated by the need to develop seismic sensors, at present ferroelectric materials have been extensively studied for applications in high-energy capacitors, energy harvesting systems, night vision sensors, and electrocaloric solid cooling, and, of particular significance, the ferroelectrics are the material-of-choice for numerous electromechanical devices, including underwater acoustic transducers, medical diagnostic and therapeutic transducers, piezoelectric actuators, and ultrasonic motors, to name a few. The progress over the past 100 years has been enormous and it is ongoing: for example, the piezoelectric coefficient d of ferroelectrics has increased from a few pico-Coulomb per Newton to several thousand pico-Coulomb per Newton, which benefits all piezoelectric sensing and actuation devices