Rhombohedral-phase barium titanate as a piezoelectric transducer

Piezoelectric transducers are characterized in that they have the ability to (1) generate a voltage when stress is applied and/or (2) produce a mechanical force when a voltage is applied. These properties are generally referred to as the "piezoelectric effect" and are found only in a limited number of materials. Specifically, when stress is applied to these materials, displacement of the crystalline structure produces a charge (or voltage) proportional to the strain. Conversely, when an electric field (or voltage) is applied to the material, the shape of the crystalline structure changes, thereby changing the dimensions of the material. A piezoelectric transducer includes a barium-titanate-based piezoelectric material having a poled, rhombohedral structure. The rhombohedral barium titanate structure can include a dopant, such as KNbO, BaHfO, BaSnO, BaZrOor KTaO. The piezoelectric transducer can be used either as an actuator or as a sensor.