  NaNbO3-based antiferroelectric materials offer a promising pathway towards
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 brief communication, 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 typically small,
deeply-embedded grains of a NaNbO3 and 0.95NaNbO3-0.05SrSnO3 ceramics,
representative of different phase transition behavior. Our results clearly
evidences the stabilizing effect of SrSnO3 on the antiferroelectric phase by
enhancing the degree 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.
