Local Structure Heterogeneity in Sm-Doped AgNbO3 for Improved Energy-Storage Performance.

AgNbO3-based antiferroelectric ceramics have been actively studied for energy-storage applications, where numerous compositional modifications have been implemented to improve their energy-storage performance. In this work, Sm2O3-doped AgNbO3 ceramics were fabricated; the microstructure, dielectric property, and phase transition behavior were investigated. Because of the structure heterogeneity induced by the rare-earth dopant, a diffused antiferroelectric-to-paraelectric phase transition was observed. High-resolution transmission electron microscopy observations confirm the existence of a local pseudo-rhombohedral structure consisting of different lattice orderings, being responsible for the local nanoscale heterogeneity. Of particular significance is the fact that the Sm3+ dopant effectively decreases the dielectric loss and increases the critical antiferroelectric-ferroelectric phase transition electric field, leading to a high energy-storage density of 4.5 J/cm3.