Janus structures of SMoSe and SVSe compositions with low enthalpy and unusual crystal chemistry. Issue 5 (1st October 2022)

• Record Type: Journal Article
• Authors: Gavryushkin, Pavel; Sagatov, Nursultan; Sukhanova, Ekaterina; Medrish, Inna; Popov, Zakhar
• Is Part Of: Journal of applied crystallography. Volume 55:Issue 5(2022)
• Page Start: 1324
• Page End: 1335
• Publication Date: 2022-10-01
• Subjects: density functional theory -- magnetic materials -- low‐dimensional structures; Crystallography -- Periodicals; 548.05
• DOI: 10.1107/S1600576722008202
• Languages: English
• ISSNs: 0021-8898

Abstract

Abstract : Promising new structures of transition metal dichalcogenides have been discovered theoretically. The low values of enthalpy suggest the possibility of experimental synthesis. Abstract : The recent synthesis of single‐layer Janus‐type transition metal dichalcogenides (TMDs) raises the question of the existence of other possible 2D structures with an asymmetric out‐of‐plane structural configuration. In the present work, a theoretical search for new Janus structures having SMoSe and SVSe compositions is performed. A detailed crystal‐chemical analysis of the predicted structures is carried out, and it is shown that some of the dynamically stable structures are characterized by crystal‐chemical features that are unique among TMDs, including quadruple Mo—Mo bonds and covalent S—S and Se—Se bonds. It is also shown that Mo‐bearing TMDs have a tendency to form strong Mo—Mo bonds with chains or isolated dimers of molybdenum atoms, while in the case of vanadium‐containing TMDs this feature is not characteristic. Two predicted crystal structures, called 1M‐SVSe and 1A′‐SMoSe, are especially promising for experimental synthesis and practical applications owing to their dynamical stability and rather low value of enthalpy compared with known structures. The enthalpy of 1M‐SVSe is 0.22 eV per formula unit lower than that of 1T‐SVSe, while the enthalpy of 1A′‐SMoSe is 0.12 eV per formula unit lower than the enthalpy of 1T‐SMoSe. The performed topological analysis showed that the predicted structures are unique and do not have analogues in the Inorganic Crystal Structure Database.