Layered structures of metal chalcogenides. (a) Single nanocrystal is composed of multiple layers stacked along the c axis by weak van der Waals force. Reproduced with permission from ref 78. Copyright 2013 The Royal Society of Chemistry. (b) Single layer of metal chalcogenides exits as various polymorphs. Each layer may have tri-, tetra-, or penta-atomic layers of metal and chalcogen. Reproduced with permission from ref 79. Copyright 1969 Taylor and Francis; www.tandfonline.com. (c) Rare GeS type of 2D layered metal chalcogenides. Reproduced with permission from ref 80(p 91). Copyright 2012 Springer. 

Contexts in source publication

Context 1

... the atoms are covalently bound to each other within one layer. The layers, however, are maintained together through weak van der Waals interactions only ( Figure 10). In this case, the shape is directly governed by the Wulff construction; the challenge is thus to control the thickness of the nanosheets down to the monolayer. ...

Context 2

... semiconductors, such as tin or germanium sulfides and selenides, can also crystallize into lamellar systems. Depending on their stoichiometry, they adopt a typical TMDC structure for SnS 2 and SnSe 2 , crystallizing into a CdI 2 -type structure, whereas the monosulfides and selenides (GeS, GeSe, SnS, and SnSe) crystallize into an orthorhombic structure as described in Figure 10. ...