nl6b05342_si_007.avi (16.07 MB)
Direct Imaging of Kinetic Pathways of Atomic Diffusion in Monolayer Molybdenum Disulfide
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posted on 2017-05-26, 00:00 authored by Jinhua Hong, Yuhao Pan, Zhixin Hu, Danhui Lv, Chuanhong Jin, Wei Ji, Jun Yuan, Ze ZhangDirect observation
of atomic migration both on and below surfaces
is a long-standing but important challenge in materials science as
diffusion is one of the most elementary processes essential to many
vital material behaviors. Probing the kinetic pathways, including
metastable or even transition states involved down to atomic scale,
holds the key to the underlying physical mechanisms. Here, we applied
aberration-corrected transmission electron microscopy (TEM) to demonstrate
direct atomic-scale imaging and quasi-real-time tracking of diffusion
of Mo adatoms and vacancies in monolayer MoS2, an important
two-dimensional transition metal dichalcogenide (TMD) system. Preferred
kinetic pathways and the migration potential-energy landscape are
determined experimentally and confirmed theoretically. The resulting
three-dimensional knowledge of the atomic configuration evolution
reveals the different microscopic mechanisms responsible for the contrasting
intrinsic diffusion rates for Mo adatoms and vacancies. The new insight
will benefit our understanding of material processes such as phase
transformation and heterogeneous catalysis.