Lead-free antiferroelectric AgNbO₃: Phase transitions and structure engineering for dielectric energy storage applications

The development of electronic materials for storing electrical energy is a thriving research field, where the materials used in batteries, supercapacitors, dielectric capacitors have attracted extensive interest in last decades. The dielectric capacitors showing unique characteristics such as high power density and large charge/discharge rate have been actively studied, where the antiferroelectrics demonstrate great potentials for dielectric energy storage applications by storing and releasing energy upon a reversible electric-field induced antiferroelectric-ferroelectric phase transition. Recently, lead-free antiferroelectric AgNbO₃ has emerged as a promising candidate to substitute conventional lead-based antiferroelectrics (such as PbZrO₃) in energy storage applications. The phase transition dynamics of AgNbO₃ is driven by a complex sequence of oxygen octahedron tilting orders in addition to cation displacement, which can be effectively engineered by a doping strategy. In this article, we present a succinct overview of the phase transition mechanisms in AgNbO₃-based ceramics and describe how the phase transition characteristics are affected by the dopants. By exploring the composition related average structure and local structural evolutions, we provide a view toward the goal of establishing a link between the phase transition and physical properties tailored for dielectric energy storage applications. © 2020 Author(s).