Hong Jinhua, Chen Xi, Li Pai, Koshino Masanori, Li Shisheng, Xu Hua, Hu Zhixin, Ding Feng, Suenaga Kazu
Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8565, Japan.
Center for Joint Quantum Studies and Department of Physics, Institute of Science, Tianjin University, Tianjin, 300350, China.
Adv Mater. 2022 May;34(19):e2200643. doi: 10.1002/adma.202200643. Epub 2022 Apr 9.
Phase transformation lies at the heart of materials science because it allows for the control of structural phases of solids with desired properties. It has long been a challenge to manipulate phase transformations in crystals at the nanoscale with designed interfaces and compositions. Here in situ electron microscopy is employed to fabricate novel 2D phases with different stoichiometries in monolayer MoS and MoSe . The multiphase transformations: MoS → Mo S and MoSe → Mo Se which are highly localized with atomically sharp boundaries are observed. Their atomic mechanisms are determined as chalcogen 2H ↔ 1T sliding, cation shift, and commensurate lattice reconstructions, resulting in decreasing direct bandgaps and even a semiconductor-metal transition. These results will be a paradigm for the manipulation of multiphase heterostructures with controlled compositions and sharp interfaces, which will guide the future phase engineered electronics and optoelectronics of metal chalcogenides.
相变是材料科学的核心，因为它能够控制具有所需性能的固体结构相。长期以来，在纳米尺度上通过设计界面和成分来操纵晶体中的相变一直是一项挑战。本文采用原位电子显微镜在单层MoS和MoSe中制备具有不同化学计量比的新型二维相。观察到多相转变：MoS → Mo S和MoSe → Mo Se，这些转变高度局域化且具有原子级锐利的边界。确定其原子机制为硫族元素2H ↔ 1T滑动、阳离子迁移和相称晶格重构，导致直接带隙减小，甚至发生半导体-金属转变。这些结果将成为通过控制成分和锐利界面来操纵多相异质结构的范例，这将为未来金属硫族化合物的相工程电子学和光电子学提供指导。
