An environmentally-benign NaNbO₃ based perovskite antiferroelectric alternative to traditional lead-based counterparts

Perovskite-structured antiferroelectric (AFE) materials, which are dominated by PbZrO₃ based solid solutions, are of particular importance owing to their excellent electromechanical properties. The driving force for new development of AFE materials is the result of environmental regulations which require the exclusion of lead components. However, currently reported lead-free AFE materials either show inferior stability or need extremely high driving fields (E_A-F) for AFE-FE phase transition. Here we report a new NaNbO₃-based solid solution with a room-temperature stable AFE phase and completely reversible field induced AFE-FE phase transition, possessing a relatively low E_A-F of ∼8 kV mm^-1, a large repeatable strain of ∼0.29%, and a large polarization difference (P_max ∼ 24 μC cm^-2, P_r ∼ 0 μC cm^-2). The local and average structures were studied by transmission electron microscopy, in situ Raman spectrum and synchrotron X-ray diffraction, revealing that the solid solution with ≥16 mol% SrTiO₃ belongs to the Pnma space group and exhibits nanoscale stripe domains of ∼55 nm, and reversibly responds to large external electric fields. This makes it a competitive lead-free AFE candidate for future applications of high-power energy-storage capacitors and large-displacement actuators. This journal is © The Royal Society of Chemistry.