Multilayer piezoelectric structure with uniform electric field

摘要

An ultrasound transducer element incorporates material of low dielectric constant to confine the electric field of a stack of piezoelectric ceramic layers. Edge segments made of material having a low dielectric constant and extending in the thickness direction are formed at opposing ends of the multilayer structure. These regions of low dielectric constant material confine the electric field to the piezoelectric ceramic material of high dielectric constant, where it remains directed vertically. In this way, when a voltage is applied between the electrodes, the piezoelectrically induced strains are almost entirely vertical. Spurious modes are therefore substantially reduced.