Balisetty Lahari, Wilfong Brandon, Zhou Xiuquan, Zheng Huafei, Liou Sz-Chian, Rodriguez Efrain E
Department of Chemistry and Biochemistry, University of Maryland College Park MD 20742 USA
Maryland Quantum Materials Center, University of Maryland College Park MD 20742 USA.
Chem Sci. 2024 Jan 24;15(9):3223-3232. doi: 10.1039/d3sc02994h. eCollection 2024 Feb 28.
Layered van der Waals (vdW) materials are susceptible not only to various stacking polymorphs through translations but also twisted structures due to rotations between layers. Here, we study the influence of such layer-to-layer twisting through the intercalation of ethylenediamine (EDA) molecules into tetragonal iron sulfide (Mackinawite FeS). Selected area electron diffraction patterns of intercalated FeS display reflections corresponding to multiple square lattices with a fixed angle between them, contrary to a single square lattice seen in the unintercalated phase. The observed twist angles of 49.13° and 22.98° result from a superstructure formation well described by the coincident site lattice (CSL) theory. According to the CSL theory, these measured twist angles lead to the formation of larger coincident site supercells. We build these CSL models for FeS using crystallographic group-subgroup transformations and find simulated electron diffraction patterns from the model to agree with the experimentally measured data.
层状范德华（vdW）材料不仅容易通过平移形成各种堆叠多晶型物，还容易因层间旋转而形成扭曲结构。在此，我们通过将乙二胺（EDA）分子插入四方硫化铁（马基诺矿FeS）来研究这种层间扭曲的影响。插层FeS的选区电子衍射图显示出对应于多个方形晶格且它们之间具有固定角度的反射，这与未插层相中的单个方形晶格不同。观察到的49.13°和22.98°的扭曲角是由符合位点晶格（CSL）理论很好描述的超结构形成导致的。根据CSL理论，这些测量的扭曲角导致形成更大的符合位点超晶胞。我们使用晶体学群-子群变换为FeS构建这些CSL模型，并发现该模型的模拟电子衍射图与实验测量数据一致。
