Abstract
Antiferroelectrics have attracted increasing research interests in recent years due to both their great potential in energy storage applications and intriguing structural characteristics. However, the links between the electrical properties and structural characteristics of distorted perovskite antiferroelectrics are yet to be fully deciphered. Here, we adopt local-structure methods to elucidate the nanoscale atomic structure of AgNbO3-based antiferroelectrics and their structural evolution upon La doping. The local structural features including interatomic distance distributions and atomic displacements have been analyzed using neutron small-box pair distribution function (PDF) refinement in conjunction with large-box Reverse Monte Carlo modelling. Our results highlight the correlation of cation displacements in AgNbO3 and its disruption by the incorporation of La, apparently in corroboration with the observed anomalous dielectric properties. Spatial ordering of cation vacancies is observed in La-doped AgNbO3 samples, which coordinates with oxygen octahedral tilting to relieve lattice strain. These results provide renewed insights into the atomic structure and antiferroelectric phase instabilities of AgNbO3 and relevant perovskite materials, further lending versatile opportunities for enhancing their functionalities.
Highlights
The research and development of high efficiency energy storage materials is becoming a thriving research field
The aim of this work is to provide a comprehensive insight into the nanoscale atomic configuration of AgNbO3 with combined pair distribution functions (PDF) and the Reverse Monte Carlo (RMC) simulation method
Modelling of the PDF reveals that the noncentrosymmetric space group Pmc21 provides a better description of the room-temperature structure of AgNbO3
Summary
The research and development of high efficiency energy storage materials is becoming a thriving research field. Compared to electrochemical energy storage systems such as batteries, dielectric capacitors are more favorable for applications which require high power densities, i.e., high charge/discharge speed [1, 2]. AgNbO3 and its derivatives are emergent lead-free antiferroelectrics whose great potential in energy storage applications makes them promising candidates to substitute conventional lead-containing antiferroelectrics. The intriguing structural characteristics and high energy storage properties of AgNbO3-based antiferroelectrics have obtained growing research interest from both fundamental and practical aspects [4,5,6,7]. Further clarifying the correlations between structure and physical property is of fundamental importance but reveals essential information for material design
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