Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln , Lincoln, Nebraska 68588, United States.
Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States.
Nano Lett. 2016 Jul 13;16(7):4410-6. doi: 10.1021/acs.nanolett.6b01541. Epub 2016 Jun 27.
By 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 SnS-parallel to the layers of ultrathin SnS2 starting material, but slanted for transformations of thicker few-layer SnS2-is 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.
通过将高分辨率透射电子显微镜和相关分析方法与第一性原理计算相结合，我们研究了层状锡二卤化物在电子束辐照下的行为。我们证明，由于电子辐照，在室温及升温条件下，硒原子的可控去除会导致 Sn-S 和 Sn-Se 体系的原子结构发生转变，从而可以诱导具有不同性质的新相。特别是，通过电子束诱导的硒原子损失，菱方层状 SnS2 和 SnSe2 可以转变为具有各向异性的正交层状 SnS 和 SnSe。所得到的 SnS 的层取向的惊人依赖性 - 与超薄 SnS2 起始材料的层平行，但对于较厚的少数层 SnS2 的转变则倾斜 - 通过空位成核为有序的 S 空位线的转变途径来合理化，这些空位线通过 Sn2S3 中间体转化为 SnS。不存在稳定的 Sn2Se3 中间体排除了硒化物的这种途径，因此 SnSe2 总是转变为基面取向的 SnSe。我们的结果提供了对转变机制的微观见解，并展示了如何通过辐照来调整层状锡二卤化物的性质，以应用于电子学、催化或储能。
