First-principles prediction of large electromechanical responses in substrate-clamped antiferroelectric oxides

It is well-known that piezoelectric responses in ferroelectrics are suppressed in thin films with respect to bulk samples, largely due to the effect of substrate clamping. However, recent work has found enormous piezoresponses in sub-micron films of antiferroelectric PbZrO3 and PbHfO3. Here we use first-principles density functional theory calculations to demonstrate how substrate clamping can enhance the out-of-plane strain response of these antiferroelectrics associated with their antipolar-to-polar phase transition. The electromechanical response is found to be highly sensitive to epitaxial orientation and strain, due to the cation displacement and octahedral tilt patterns. We posit corresponding “design principles” for maximizing the phase transition-induced piezoresponse in PZO and other antiferroelectrics.