Measuring the electric field dependence of the elastic moduli of Pb(Mg1/3Nb2/3)O3-based relaxor ferroelectrics

The field dependence of the Young´s modulus of Pb(Mg_1/3Nb_2/3)O₃ (PMN)-based relaxor ferroelectric ceramics has been determined using a pulse-echo (ultrasound) method while simultaneously applying a low-frequency, quasi-static voltage of high amplitude. The “short-circuit” (constant-E) stiffness was found to decrease up to 30% at 1 MV/m in commercial grade PMN samples operated in their transition temperature region. Correlation of this behavior with the polarization and electrically induced strain responses has been used to determine the electromechanical coupling. The electrical energy transferred to an unconstrained (mechanically free) sample, i.e., electromechanical coupling, varies significantly with the field dependence of the elastic modulus