Superelastic-like nonlinear deformation hidden in ferroelectric ceramics

Abstract

The mechanical response of ferroelectric (piezoelectric) ceramics under high stress conditions has a crucial role from the perspective of engineering applications such as advanced actuator systems. In this study, we perform first-principles calculations to clarify the deformation behavior and (ideal) tensile strength for typical ferroelectric ceramics of PbTiO3 (PTO) under high mechanical loading. We find the superelastic-like nonlinear deformation behavior in ferroelectric PTO. In addition, it has several inflection points and shows a large critical strain compared to the paraelectric phase. We conclude that the unique nonlinear deformation in PTO originates from attributable to the displacement of oxygen atoms due to the ferroelectric phase transition based on analyzing the interatomic distances of each atom and an integrated crystal orbital Hamiltonian population with respect to strain. Furthermore, we also calculate the piezoelectric coefficient for PTO and reveal that it shows the singular peak at inflection points of the stress–strain curve. Unveiling and engineering the hidden superelastic-like deformation in the ferroelectric phase may open promising paradigms for functional piezoelectric devices.