Local structural origin of relaxor antiferroelectric behavior in NaNbO3-based ceramics

Abstract

Relaxor-antiferroelectrics (relaxor-AFEs), known for their double polarization–electric field (P-E) hysteresis loops and relaxor characteristics, exhibit outstanding energy storage performance compared to other dielectric materials. However, the origins of their antiferroelectric-like behavior and relaxor features remain unclear due to their complex local structure. In this study, we designed relaxor-AFEs with a high degree of relaxor component and stable antiferroelectric behavior. The recoverable energy density (W_rec) of up to 4.6J/cm³ and energy efficiency of ∼ 79 % were achieved in a 0.76NaNbO₃-0.16Na_0.5Bi_0.5TiO₃-0.08CaTiO₃ ceramic, demonstrating excellent thermal and frequency stability. The multiphase local polarization configuration was confirmed by atomic-resolution annular dark-field scanning transmission electron microscopy (ADF STEM). Additionally, integrated differential phase contrast (iDPC) images revealed an enhanced antiferrodistortion (AFD) induced by incorporating component with low tolerance factor, contributing to stable antiferroelectric behavior. The relationship between chemical heterogeneity, polarization configuration and energy storage performance was systematically established. This work provides insights into the structure origin and underlying mechanisms for relaxor-AFE performance, with potential implications to guide the development of advanced energy-storage dielectric materials.