Mchanics of large electrostriction in ferroelectrics

摘要

The complex arragnement of domains observed in ferroeletric crystals is a consequence of multiple energy minima of the crystal free energy density. Since the total energy is a sum of the free energy, and electric land mechancial work, switching between the different energetically equivalent domain states can be achieeved by both electrical and mechancial means. for many ferroelectric materials, this results in an electrostrictive phenomenon resultingfrom domain switching. I the current study, the electrostrictive behavior of single crystal ferroelectric perovskites has been investigated experimetnally. Experimetns have been performed in which a crystal of barium titanate is exposed to a constant compressive stress and an oscillating electric field and global deformation is measured. The combined electromechanical loading results in a cycle of stress and electric field induced 90-degree domain switching. The domain switching cycle results in a measurable strain response theoretically limited by the crystalographic unit cel ldimensions. Induced strains of more than 0.8