Precession Electron Diffraction Tomography for Solving Complex Modulated Structures: the Case of Bi5Nb3O15
Precession Electron Diffraction Tomography for Solving Complex Modulated Structures: the Case of Bi5Nb3O15
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DOI：
10.1021/ic400529s
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发表时间：
2013-05-20
影响因子：
4.6
通讯作者：
Barrier, Nicolas
中科院分区：
文献类型：
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作者：
Boullay, Philippe;Palatinus, Lukas;Barrier, Nicolas
通过使用层析技术结合电子束的进动的电子衍射来解决ID干涉调制相Bi 5Nb 3O 15 [超空间群X2mb（0 b0）000，a = 5.46781（7）埃，B = 5.47381（8）埃，c = 41.9005（5）埃，并且q = 0.17588（8）B*]的晶体结构。通过对粉末X射线衍射（PXRD）的细化进一步验证了（3 + 1）D结构。一个连贯的图片，这种化合物的真实性质，调解实验观察不同的团体使用透射电子显微镜和PXRD。Bi5Nb3O15不具有混合层Aurivillius型结构，但确实包含结构元素，[Bi2O2]（2+）板和钙钛矿样块，具有Aurivillius相的特征。沿调制方向B存在沿着的非周期性晶体学剪切面（CSP）导致形成包含连续和不连续的[Bi 2 O 2]（2+）和类钙钛矿八面体层的原始层状结构。在CSP之间，这两个结构元素的堆叠表现出前所未有的非均匀序列，指的是Aurivillius阶段。
The crystal structure of the ID incommensurately modulated phase Bi5Nb3O15 [superspace group X2mb(0b0)000, a = 5.46781(7) angstrom, b = 5.47381(8) angstrom, c = 41.9005(5) angstrom, and q = 0.17588(8)b*] is solved by electron diffraction using a tomography technique combined with precession of the electron beam. The (3 + 1)D structure is further validated by a refinement against powder X-ray diffraction (PXRD). A coherent picture of the true nature of this compound is obtained, conciliating experimental observations made by different groups using transmission electron microscopy and PXRD. Bi5Nb3O15 does not have a mixed-layer Aurivillius-type structure but does contain structural elements, [Bi2O2](2+) slabs, and perovsldte-like blocks, characteristic of Aurivillius phases. The presence of aperiodic crystallographic shear planes (CSPs) along the modulated direction b leads to the formation of an original layered structure containing both continuous and discontinuous [Bi2O2](2+) and perovskite-like octahedral layers. Between CSPs, the stacking of these two structural elements exhibits an unprecedented nonuniform sequence referring to Aurivillius phases.