Constructing local structure heterogeneity in AgNbO3-based antiferroelectrics: Achieving excellent anti-fatigue and energy storage properties

AgNbO3 ceramics are important candidates for developing high-property dielectric capacitors because of their unique field-induced antiferroelectric (AFE)-ferroelectric (FE) phase transformation behavior and good environmental friendliness. However, until now, they have not yet exhibited simultaneously ultrahigh recoverable energy density (Wrec) and efficiency (eta), and superior electrical fatigue resistance. Herein, we design a heterovalence-doping-enabled local structure heterogeneity strategy to achieve AgNbO3-based ceramics with excellent anti-fatigue and capacitive characteristics. The replacement of A-site Ag+ with higher valence Sm3+, and the substitution of lower electronegativity Ta5+ for B-site Nb5+ decrease the [Nb/TaO6] octahedral tilting, destroy the long-range ordering of AFE domains and produce low-atom-displacement regions, as confirmed by the atomic-scale electron microscopy. These are in favor of improving AFE features, refining P-E curves, and decreasing electric field-induced strain. Consequently, an ultrahigh Wrec of 8.03 J/cm3, and a large eta of 74.77 % are obtained in the (Ag0.94Sm0.02)(Nb0.75Ta0.25)O3 ceramic. More interestingly, the Wrec and eta both show excellent anti-fatigue characteristics with less than 2.6 % degradation even after 106 cycles, far superior to those obtained in other AgNbO3 systems with only 104 cycle stability.