Ruddlesden-Popper结构杂化非常规铁电体的研究进展

张碧辉, 刘小强, 陈湘明

Recent Progress of Hybrid Improper Ferroelectrics with Ruddlesden-Popper Structure

ZHANG Bihui, LIU Xiaoqiang, CHEN Xiangming

图16 (a) 390 kV/cm条件下采用PUND法测得的Li2La2Ti3O10陶瓷的P−E电滞回线和J−E电流密度曲线[149]; (b)基于DFT计算的三层R-P结构Li2La2Ti3O10的不同对称性相对于0 K时能量最低Pc相的能量[149]; (c) PUND法测得的Li2Nd2Ti3O10陶瓷的室温P−E电滞回线[150]; (d) Li2La2Ti3O10(LLTO)和Li2Nd2Ti3O10(LNTO)陶瓷的氧八面体畸变角度θT和θR[150]; (e)基于Rietveld精修的Li2La2Ti3O10陶瓷晶体结构示意图(绿色、棕色和红色球分别代表Li+、La3+和O2−离子, 而Ti4+离子位于氧八面体的中心)[149]; (f)通过玻恩有效电荷方法计算的Li2La2Ti3O10中每一层对应的极化贡献[149]

Fig. 16 (a) Room temperature P−E loop and J−E curves measured at 390 kV/cm by PUND method[149]; (b) Calculated energies for Li2La2Ti3O10 with different crystal symmetries in the triple-layered R-P structure relative to the lowest energy Pc phase at 0 K[149]; (c) Room temperature P−E loops of Li2Nd2Ti3O10 ceramics measured through PUND method[150]; (d) Rotation (θR) and tilt (θT) angles of Li2La2Ti3O10 (LLTO) and Li2Nd2Ti3O10 (LNTO) ceramics, respectively[150]; (e) Schematic diagrams of crystal structures for Li2La2Ti3O10 ceramics based on the Rietveld refinement (the green, brown, and red balls represent Li+, La3+, and O2− ions, respectively, while Ti4+ cations reside in the oxygen octahedra center)[149]; (f) Layer-by-layer contributions to polarization in Li2La2Ti3O10 calculated by the Born effective charge mode[149]