Octahedral Tilting and Modulation Structure in Perovskite-Related Compound La1/3NbO3
Octahedral Tilting and Modulation Structure in Perovskite-Related Compound La1/3NbO3
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钙钛矿相关化合物 La1/3NbO3 的八面体倾斜和调制结构
DOI：
10.1002/pssb.202100561
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
Masanobu Nakayama
中科院分区：
文献类型：
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作者：
Yusuke Sakai;Daisuke Urushihara;Toru Asaka;Koichiro Fukuda;Zijian Yang;Naoto Tanibata;Hayami Takeda;Masanobu Nakayama
利用X射线粉末衍射、透射电子显微镜（TEM）和计算方法研究了钙钛矿la1 / 3nbo3的晶体结构。观察到nbo6八面体倾斜，并证实了在Glazer符号中是ana - b0 - c0方式。在la1 / 3nbo3中观察到不相称的调制结构。利用扫描透射电镜（STEM）分析和蒙特卡罗模拟，调制结构显示源于La和空位的条纹排列。由调制结构引起的卫星反射在电子衍射图中表现为漫射散射。通过STEM分析和分子动力学计算，得出了扩散散射的起源是不同晶体取向的纳米孪晶变体的存在。nbo6八面体中的Nb离子表现出一种偏离中心的位移，就像伪Jahn-Teller畸变。发现Nb离子的位移与La离子的浓度调制是协同的。
The crystal structure of theA‐site‐deficient perovskite La1/3NbO3is investigated using X‐ray powder diffraction, transmission electron microscopy (TEM), and computational methods. The NbO6octahedral tilting is observed and confirmed to be in ana−b0c0manner in Glazer's notation. An incommensurate modulation structure in La1/3NbO3is observed. Using scanning TEM (STEM) analyses and Monte Carlo simulations, the modulated structure is shown to originate from a striped arrangement of La and vacancies. The satellite reflections arising from the modulation structure are observed as a diffuse scatter in the electron diffraction patterns. By analyses with STEM and molecular dynamics calculations, it is concluded that the origin of diffuse scattering is the existence of nanoscale twin variants with different crystal orientations. The Nb ions in NbO6octahedra represent an off‐center shift like a pseudo‐Jahn–Teller distortion. The shift of Nb ions is found to be cooperative with the concentration modulation of La ions.