Heterogeneous Antiferroelectric Ordering in NaNbO₃–SrSnO₃ Ceramics Revealed by Direct Superstructure Imaging

NaNbO 3 -based antiferroelectric materials offer a promising pathway toward greener and more cost-effective energy storage devices. However, their intrinsic structural instabilities often lead to reduced energy density that compromises their performance and longevity. In this letter, we demonstrate how Dark-Field X-ray Microscopy─when carried out on the characteristically weak 1/4{843} pc superstructure reflection─can map the antiferroelectric phase and its strain heterogeneity in small, deeply embedded grains of a NaNbO 3 and 0.95NaNbO 3 –0.05SrSnO 3 ceramics, representative of different phase transition behavior. Our results illustrate the stabilizing effect of SrSnO 3 on the antiferroelectric phase via the enhancement of mesostructural order. In doing so, our method establishes a new platform for exploring the impact of disorder on the long-range strain heterogeneity within antiferroelectrics and other materials with modulated crystal structures.