5.5.1 Difference between Pyroelectric and Ferroelectric Material

Although both ferroelectric and pyroelectric materials must be non-centrosymmetric  and polar, the essential difference between them lies when an electric field is applied.  While a change in temperature below Curie temperature leads to the creation of dipole along the polar axis by slight movement of atoms from their neutral positions (A), a reverse electric field can reverse the direction of polarization in a ferroelectric but not in a pyroelectric material (B). However, when the material is heated above Curie temperature, the atoms come back to their equilibrium positions (C).