Piezoelectric effects in ferroelectric ceramics

Ferroelectric ceramics exhibit piezoelectric effects and optical birefringence that are electrically controllable. Consequently, these ceramics are applicable to a wide variety of devices. An article in the February issue has already described electrically actuated light valves and electrically controlled optical filters. The present article deals with the piezoelectric behavior of ferroelectric ceramics. Since, macroscopically, these materials are nearly isotropic, a discussion of their piezoelectric behavior can provide uncluttered¿and surprising¿insight into the theory of piezoelectric energy conversion.