In our recent publication entitled Domain morphology of newly designed lead-free antiferroelectric NaNbO3-SrSnO3 ceramics (J. Am. Ceram. Soc. 2021, 104: 3715-3725), Ding et al. characterized the domain morphology of the newly designed NaNbO3 based antiferroelectric materials by transmission electron microscopy.
Via electron diffraction and centered dark-field imaging, antiferroelectricity is confirmed to be maintained in all compositions, manifested by the characteristic ¼ superlattice reflections. By investigating the antiferroelectric domains and domain boundaries in NaNbO3, we demonstrate that antiphase boundaries are present, and their irregular periodicity is responsible for the streaking features along the ¼ superlattice reflections in the electron-diffraction patterns. The signature domain blocks observed in pure NaNbO3 are maintained in the SrSnO3-modified ceramics but disappear when the amount of SrSnO3 reaches 7 mol.%. In particular, a well-defined and distinct domain configuration is observed in the NaNbO3 sample modified with 5 mol.% SrSnO3, which presents a parallelogram domain morphology.