Fifty years of ferroelectrics

Piezoelectricity is an important part of ultrasound, frequency control, and ferroelectricity, the three major divisions of UFFC. During the last fifty years there have been great improvements in piezoelectric materials and piezoelectric transducers. Poled ferroelectric ceramics and single crystals with multiple tuned instabilities have huge piezoelectric coefficients and nearly perfect electromechanical coupling, and transducer design has made equally important advances through the use of composite structures with integrated electronics. A few historical highlights, along with some thoughts for the future, are incorporated in this paper.