Insights into enhanced antiferroelectricity in doped-niobate perovskites for high energy-storage density applications

Abstract

Lead-free antiferroelectric (AFE) ceramics have attracted increasing attention in recent years for application in high-power capacitors due to their environmental friendliness and high energy density. Among these ceramics, NaNbO3 is noteworthy as one of the few lead-free perovskites displaying an AFE structure. However, despite the nature of AFE symmetry in NaNbO3 with Nb antipolar state, in most cases, it behaves like a ferroelectric (FE) material with an external electric field and exhibits a single polarization-electric field (P-E) hysteresis loop. In order to enhance the antiferroelectricity, a composition modification strategy based on the tolerance factor (t) has been used to stabilize the AFE phase effectively. Yet, in the context of NaNbO3 ceramics, the impact of doping on the evolution of antiferroelectricity has remained unexplored. Through first-principles calculations, we unveil how the chemical modification of NaNbO3 enhances antiferroelectricity by investigating local distortions that favor the AFE state over the FE state in solid solutions. This adjustment in the relative stability between the FE state and AFE state results in a significant modification in the switching barrier in NaNbO3-based antiferroelectrics, ultimately leading to well-defined double polarization loops. This work offers a rationalized atomic-scale perspective on the AFE-FE phase transition in NaNbO3-based ceramics, aiming to contribute to the development of novel lead-free antiferroelectric oxides for energy storage applications.