Large Electromechanical Response and Field-Induced Shape Memory Effect in Ferroelectric Ceramics

Electric-field-induced shape memory effect has potential applications in electromechanical actuator. Here, this study proposes the a phase structure design routine in (1-x)(75Na_0.5Bi_0.5TiO₃-25SrTiO₃)-xPbTiO₃ ceramics to obtain large electromechanical response and shape memory effect. It is found that the shape memory effect is closely related to the bending deformation induced by asymmetric polarization between positive and negative electrodes, which is resulted from the reductions of Bi³⁺ and Pb²⁺ because of electron injection from negative electrode. In addition, the content of ferroelectric phase with P4 mm structure and c/a ratio increase with PbTiO₃ content increasing, and the coercive field of the ceramics is also enhanced by the PbTiO₃ addition, Combing the crystal structure and chemical composition, the field-induced deformation achieves 2.77% and shape memory effect is 1.75% at 80kV cm⁻¹ and 0.1 Hz in the ceramic with the content of PbTiO₃ is 40%.