National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan.
1] Department of Electronic Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan [2].
Nat Nanotechnol. 2014 May;9(5):391-6. doi: 10.1038/nnano.2014.64. Epub 2014 Apr 20.
Phase transitions can be used to alter the properties of a material without adding any additional atoms and are therefore of significant technological value. In a solid, phase transitions involve collective atomic displacements, but such atomic processes have so far only been investigated using macroscopic approaches. Here, we show that in situ scanning transmission electron microscopy can be used to follow the structural transformation between semiconducting (2H) and metallic (1T) phases in single-layered MoS2, with atomic resolution. The 2H/1T phase transition involves gliding atomic planes of sulphur and/or molybdenum and requires an intermediate phase (α-phase) as a precursor. The migration of two kinds of boundaries (β- and γ-boundaries) is also found to be responsible for the growth of the second phase. Furthermore, we show that areas of the 1T phase can be controllably grown in a layer of the 2H phase using an electron beam.
相变可以在不添加任何额外原子的情况下改变材料的性质，因此具有重要的技术价值。在固体中，相变涉及集体原子位移，但到目前为止，这些原子过程仅使用宏观方法进行了研究。在这里，我们表明，原位扫描透射电子显微镜可以用于以原子分辨率跟踪单层 MoS2 中半导体（2H）和金属（1T）相之间的结构转变。2H/1T 相变涉及滑动的硫和/或钼原子层，并且需要中间相（α 相）作为前体。还发现两种类型的边界（β-和 γ-边界）的迁移也负责第二相的生长。此外，我们表明，使用电子束可以在 2H 相的层中可控地生长 1T 相的区域。
