ABSTRACT
All dielectric materials when subjected to an external electric eld undergo change in dimensions. This is due to the displacements of positive and negative charges within the material. A dielectric crystal lattice may be considered to be made up of cations and anions connected by springs (interionic chemical bonds). When an external electric eld is applied to the material, the cations get displaced in the direction of the electric eld and the anions get displaced in the opposite direction, resulting in net deformation of the material. The change in dimension may be very small or may be quite signicant, depending on the crystal class to which the dielectric belongs.
