Strain-dielectric response of dielectrics as foundation for electrostriction stresses

The apparent deformation due to an electric field does not rigorously describe the electrostriction phenomenon. This is in part due to uncertainties in the mechanical constraints at the specimen boundaries. Such constraints are very critical in thin films. Determining the electric-field-induced stress seems to be a more adequate approach to electrostriction. General thermodynamic considerations identify the electrostriction stress through strain derivatives of the dielectric displacement. Consequently, the derivatives of the dielectric coefficients are termed the electrostriction parameters. The strain-dielectric response of a material, which is called dielectrostriction, provides an avenue to study electrostriction. However, controlling the mechanical boundary conditions of a thin-film specimen can be challenging. This problem can be overcome by using a proposed planar capacitor sensor which does not require any mechanical contact with the specimen. The theoretical background and experimental results for the dielectrostriction study of a uniaxially loaded specimen are presented and discussed.