Crystal twinning of bicontinuous cubic structures
Crystal twinning of bicontinuous cubic structures
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DOI：
10.1107/s2052252519017287
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发表时间：
2020-03-01
期刊：
影响因子：
3.9
通讯作者：
Che, Shunai
中科院分区：
文献类型：
--
作者：
Han, Lu;Fujita, Nobuhisa;Che, Shunai
软物质中的双连续立方结构由两个相互缠绕的晶体组成，它们被一个分隔层隔开。结合实验、数值模拟和微分几何技术，我们研究了双连续立方结构中的孪生缺陷。我们首先证明，一个孪生边界是最有可能发生在一个平面，几乎垂直切割的分区层，使孪生所造成的扰动仍然是最小的。这一原则可以作为一个标准，以确定潜在的孪晶边界，通过详细的调查，其特征在于金刚石和螺旋面的介孔二氧化硅晶体证明。然后，我们讨论了一个孪晶界可以导致堆垛层错的安排层间附件在结构形成的早期阶段。它进一步表明，增强的曲率波动附近的孪晶边界将成本的能量，因为几何挫折，这将缓解实验观察到的晶体畸变。
Bicontinuous cubic structures in soft matter consist of two intertwining labyrinths separated by a partitioning layer. Combining experiments, numerical modelling and techniques in differential geometry, we investigate twinning defects in bicontinuous cubic structures. We first demonstrate that a twin boundary is most likely to occur at a plane that cuts the partitioning layer almost perpendicularly, so that the perturbation caused by twinning remains minimal. This principle can be used as a criterion to identify potential twin boundaries, as demonstrated through detailed investigations of mesoporous silica crystals characterized by diamond and gyroid surfaces. We then discuss that a twin boundary can result from a stacking fault in the arrangement of inter-lamellar attachments at an early stage of structure formation. It is further shown that enhanced curvature fluctuations near the twin boundary would cost energy because of geometrical frustration, which would be eased by a crystal distortion that is experimentally observed.