Formation of 2D transition metal dichalcogenides on TiC1-xA x surfaces (A = S, Se, Te): A theoretical study

Using first principle density functional calculations, we study the formation of 2D transition metal dichalcogenides (TMDs) on TiC 1-xAx, (A = S, Se, and Te) surfaces. We examine the structural misfits between chalcogen-containing TiC and different TMDs and demonstrate that the conditions for formation of TMDs are fulfilled in TiC 1-xAx. We also demonstrate the influence of chalcogens on the cohesive properties and electronic structure of the carbides. We find that they react with W and form W-dichalcogenides. In the experimentally reported Ti-C-S nanocomposite coatings, the carbide grains are embedded in an amorphous carbon matrix. We discuss here the role of this matrix in the reaction. We propose that TiC1-xTex and TiC1-xSex are the favorable sources for dichalcogenide formation and suggest an alternative way to produce 2D materials in general. Furthermore, we argue that using Ti-C-Te or Ti-C-Se in nanocomposite coatings may be more advantageous for tribological applications than that of Ti-C-S. © 2013 Materials Research Society.