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9 (a)根据空间群对称性分析得到Sr3Sn2O7随温度变化的四个相结构[118]; (b)研究建立的Sr3Sn2O7的相图[118]; (c)根据300 K条件下的NPD精修结果计算的晶体结构分层极化(左图), [010]面的晶体结构示意图(右图), 其中Sr、Zr和O原子分别为灰色、蓝色和红色[119]; (d) Sr3Hf2O7中原子和分层极化对宏观极化的贡献, Sr1−O表示钙钛矿层之间的SrO层, Sr2−O表示岩盐层和钙钛矿层之间的SrO层[120]

Fig. 9 (a) Crystal structures of four phases observed experimentally for Sr3Sn2O7, specified by space group symmetry and Glazer tilt notation[118]; (b) Phase diagram of Sr3Sn2O7 established in the present study[118]; (c) Calculated layer-resolved polarization using a point-charge approximation for the crystal structure refined against NPD data at 300 K (left panel), [010] projected crystal structure (right panel) with Sr, Zr, and O atoms in gray, blue, and red, respectively[119]; (d) Atomic contributions and layer-by-layer contributions to polarization in Sr3Hf2O7, in which Sr1-O represents the SrO layer between perovskite layers, and Sr2-O represents the SrO layer between rock-salt and perovskite layers[120]