Piezoelectricity

Summary

Piezoelectricity is the coupling, in certain crystals and ceramics, between mechanical stress and electric polarization. In the direct effect, a stress produces an electric charge on the surfaces; in the converse effect, an applied electric field produces a strain. In the linear theory the coupling is a third-order tensor, which vanishes in every crystal with a centre of symmetry. Piezoelectric materials such as quartz and lead zirconate titanate are used in sensors, actuators, ultrasound transducers and quartz clocks.