Application of multilayered ceramic capacitor to Pb-free electromechanical transducer

Piezoelectric ceramic transducers are widely used in ultrasonic electronics. However, since many of them contain Pb, they are regarded to be undesirable from the viewpoint of environmental pollution. Therefore, Pb-free piezoelectric transducers are desired for practical applications. In this paper, we examine a Pb-free transducer. As the structure of the Pb-free transducer we use a multilayered ceramic capacitor because it consists of Pb-free materials. We expect that the multilayered ceramic capacitor will operate not only as an electrostrictive transducer, but also as a good electrostatic transducer because of its very thin layered construction and high dielectric constant. It has the following advantages: it does not contain Pb and does not need poling treatment, which is usually required by conventional piezoelectric ceramic transducers. The first part of this paper describes the operation principle of the new Pb-free transducer and in the second part, basic experiments are described.