Review on field-induced phase transitions in lead-free NaNbO₃-based antiferroelectric perovskite oxides for energy storage

Emerging new applications of antiferroelectric perovskite oxides based on their fascinating phase transformation between polar and nonpolar states have provided considerable attention to this class of materials even decades after the discovery of antiferroelectricity. After presenting the challenge of formulating a precise definition of antiferroelectric materials, we briefly summarize proposed applications. In the following, we focus on the crystallographic structures of the antiferroelectric and ferroelectric phases of NaNbO₃, which is emerging as a promising alternative to PbZrO₃-based systems. The field-induced phase transition behavior of NaNbO₃-based AFE materials in the form of single crystals, bulk ceramics, and multilayer ceramic capacitors is reviewed. Recent advances in a group of materials exhibiting high energy storage performance and relaxor-like behavior are also covered. The influence of electrode geometry on phase transition behavior and thus on the energy storage property is briefly addressed. The review concludes with an overview of the remaining challenges related to the fundamental understanding of the scientific richness of AFE materials in terms of structure, microstructure, defect transport under high fields, and phase transition dynamics required for their future development and applications.