Pyroelectricity

Pyroelectricity is a property of certain crystals that are naturally electrically polarized and so contain large electric fields, giving them the ability to generate a temporary voltage when heated or cooled. A change in temperature slightly shifts the positions of atoms within the crystal structure, changing the material's polarization and producing a voltage across the crystal; if the temperature then holds steady, the voltage gradually disappears through leakage current. The name comes from the Greek word for fire, and the effect underlies devices such as pyroelectric fusion, though it is a general property of certain crystal structures rather than a single device.