Behavior of piezoelectric actuators under high electric field

Behavior of piezoelectric actuators (bimorph, unimorph, RAINBOW, and shear-mode) fabricated from soft ceramics has been investigated in a wide electric field and frequency range. The electrical admittance, mechanical displacement, and blocking force of these transducers have been found to be highly dependent on the magnitude of driving field. The resonant frequency and mechanical quality factor of bending vibrations for all but shear-mode actuators decreases significantly with increasing driving field. Analysis shows that despite a large variation in the quasi-static electrical admittance and reduced tip displacement of bimorph, unimorph, and RAINBOW cantilevers with driving field, their ratio is almost a constant, which characterizes the ratio of dielectric permittivity /spl epsi//sub 33//sup T/ to piezoelectric coefficient d/sub 31/.