Gao Jing, Li Wei, Liu Jue, Li Qian, Li Jing-Feng
State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Research (Wash D C). 2022 Feb 25;2022:9782343. doi: 10.34133/2022/9782343. eCollection 2022.
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 AgNbO-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 AgNbO 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 AgNbO 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 AgNbO and relevant perovskite materials, further lending versatile opportunities for enhancing their functionalities.
近年来，反铁电体因其在储能应用中的巨大潜力和引人入胜的结构特性而吸引了越来越多的研究兴趣。然而，畸变钙钛矿反铁电体的电学性质与结构特性之间的联系尚未完全弄清楚。在此，我们采用局域结构方法来阐明基于AgNbO的反铁电体的纳米级原子结构及其在La掺杂时的结构演变。利用中子小盒对分布函数（PDF）精修结合大盒反向蒙特卡罗建模，分析了包括原子间距离分布和原子位移在内的局域结构特征。我们的结果突出了AgNbO中阳离子位移的相关性及其因La掺入而受到的破坏，这显然与观察到的异常介电性质相一致。在La掺杂的AgNbO样品中观察到阳离子空位的空间有序排列，其与氧八面体倾斜协同作用以缓解晶格应变。这些结果为AgNbO及相关钙钛矿材料的原子结构和反铁电相不稳定性提供了新的见解，进一步为增强其功能提供了多种机会。
