Electrostrictive strain in low-permittivity dielectrics

A single-beam interferometer capable of resolving displacements on the order of 10^-4 Å was used to examine the field-induced displacement in several low-permittivity dielectric materials. The experimental principle and procedures of the single-beam interferometer are described in this article. The importance and the accuracy of the Maxwell stress and the thermal stress corrections are also discussed. We present in this article the field-induced strains and the apparent electrostrictive coefficients of several common dielectric materials, including Al₂O₃, BgO, MgO, AlN ceramics, and SiO₂ glass. Under application of an electric field, these common ceramic materials become thicker in the field direction, while glasses and glass-ceramics get thinner. The magnitude of the displacements varies between 10^-2 to 10^-3 Å under 1 MV/m electric field. By comparison, the field-induced displacements in these common electronic materials are approximately 3 to 5 orders of magnitude smaller than those observed in relaxor materials, such as PMN and PVDF, and soft polymers.