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

NaNbO3-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 NaNbO3 and 0.95NaNbO3–0.05SrSnO3 ceramics, representative of different phase transition behavior. Our results illustrate the stabilizing effect of SrSnO3 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.