Piezoelectricity is a coupling between a material's mechanical and electrical behaviors.
In the simplest of terms, when a piezoelectric material is squeezed, an electric charge collects
on its surface. Conversely, when a piezoelectric material is subjected to a voltage drop,
it mechanically deforms.
Many crystalline materials exhibit piezoelectric behavior. A few materials exhibit the phenomenon strongly
enough to be used in applications that take advantage of their properties.
lead titanate zirconate ceramics (e.g.
and polyvinylidene flouride (a polymer film).
On a nanoscopic scale, piezoelectricity results from a nonuniform charge distribution within
a crystal's unit cells. When such a crystal is mechanically deformed, the positive and negative charge centers
displace by differing amounts. So while the overall crystal remains electrically neutral, the difference
in charge center displacements results in an electric polarization within the crystal. Electric polarization due to
mechanical input is perceived as piezoelectricity.
From an engineering or modeling point of view, piezoelectricity results in a change to a
material's constitutive properties. Many finite element
codes include piezoelectric modeling capability.