Lead-free antiferroelectric AgNbO_3: Phase transitions and structure engineering for dielectric energy storage applications

摘要

The development of electronic materials for storing electrical energy is a thriving research field, where the materials used in batteries, super-capacitors, and 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 AgNbO_3 has emerged as a promising candidate to substitute conventional lead-based antiferroelectrics (such as PbZrO_3) in energy storage applications. The phase transition dynamics of AgNbO_3 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 AgNbO_3-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.