nl6b01541_si_002.avi (2.79 MB)
Electron-Beam Induced Transformations of Layered Tin Dichalcogenides
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posted on 2016-06-23, 00:00 authored by E. Sutter, Y. Huang, H.-P. Komsa, M. Ghorbani-Asl, A.V. Krasheninnikov, P. SutterBy
combining high-resolution transmission electron microscopy and associated
analytical methods with first-principles calculations, we study the
behavior of layered tin dichalcogenides under electron beam irradiation.
We demonstrate that the controllable removal of chalcogen atoms due
to electron irradiation, at both room and elevated temperatures, gives
rise to transformations in the atomic structure of Sn–S and
Sn–Se systems so that new phases with different properties
can be induced. In particular, rhombohedral layered SnS2 and SnSe2 can be transformed via electron beam induced
loss of chalcogen atoms into highly anisotropic orthorhombic layered
SnS and SnSe. A striking dependence of the layer orientation of the
resulting SnSparallel to the layers of ultrathin SnS2 starting material, but slanted for transformations of thicker few-layer
SnS2is rationalized by a transformation pathway
in which vacancies group into ordered S-vacancy lines, which convert
via a Sn2S3 intermediate to SnS. Absence of
a stable Sn2Se3 intermediate precludes this
pathway for the selenides, hence SnSe2 always transforms
into basal plane oriented SnSe. Our results provide microscopic insights
into the transformation mechanism and show how irradiation can be
used to tune the properties of layered tin chalcogenides for applications
in electronics, catalysis, or energy storage.