Origin of the Apparent Electric-Field Dependence of Electrostrictive Coefficients

TL;DR

This paper demonstrates that the apparent electric-field dependence of electrostrictive coefficients is due to neglecting higher-order effects, and provides a methodology to accurately predict electrostrictive behavior by including these effects.

Contribution

The authors introduce a methodology accounting for higher-order electromechanical phenomena to correctly interpret electrostrictive coefficients and predict saturation behavior.

Findings

Electrostrictive coefficients are actually constant when higher-order effects are considered.

High-order coefficients' signs enable prediction of saturation behavior.

Method applied successfully to classical and giant electrostrictors.

Abstract

Electrostrictive materials exhibit a strain that is proportional to the square of the induced polarization. In linear dielectrics where the permittivity is constant, this electromechanical strain is also proportional to the square of the electric field. However, under increasing amplitudes of the driving field, the electromechanical strain sometimes saturates; the electrostrictive coefficients therefore appear to depend on the amplitude of the electric field used to measure them. Here, we present a methodology showing that this apparent field dependence is a consequence of neglecting higher-order electromechanical phenomena. When these are taken into account, not only do the electrostrictive coefficients remain constant but the signs of the high-order coefficients enable the prediction of the saturation behavior from a single measurement. We illustrate this approach on both classical and non-classical (so-called ``giant'') electrostrictors.