Electronic and mechanical properties of stiff rhenium carbide monolayers: A first-principles investigation

Siriwardane E. M. D., Karki P., SEVİK C., Cakir D.

APPLIED SURFACE SCIENCE, vol.458, pp.762-768, 2018 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 458
  • Publication Date: 2018
  • Doi Number: 10.1016/j.apsusc.2018.07.058
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.762-768
  • Keywords: Density functional theory, Rhenium carbide monolayers, Electronic properties, Mechanical properties, INITIO MOLECULAR-DYNAMICS, TOTAL-ENERGY CALCULATIONS, ELASTIC PROPERTIES, TRANSITION, GRAPHENE, CARBON, SEMICONDUCTOR, PHOSPHORENE, NITRIDES, BORIDES
  • Anadolu University Affiliated: Yes


In this study, we predicted two new stable metallic Re-C based monolayer structures with a rectangular (r-ReC2) and a hexagonal (h-Re2C) crystal symmetry using first-principle calculations based on density functional theory. Our results obtained from mechanical and phonon calculations and high-temperature molecular dynamic simulations clearly proved the stability of these two-dimensional (2D) crystals. Interestingly, Re-C monolayers in common transition metal carbide structures (i.e. MXenes) were found to be unstable, contrary to expectations. We found that the stable structures, i.e. r-ReC2 and h-Re2C, display superior mechanical properties over the well-known 2D materials. The Young's modulus for r-ReC2 and h-Re2C are extremely high and were calculated as 351 (1310) and 617 (804) N/m (GPa), respectively. Both materials have larger Young's modulus values than the most of the well-known 2D materials. We showed that the combination of the short strong directional p-d bonds, the high coordination number of atoms in the unit-cell and high valence electron density result in strong mechanical properties. Due to its crystal structure, the r-ReC2 monolayer has anisotropic mechanical properties and the crystallographic direction parallel to the C-2 dimers is stiffer compared to perpendicular direction due to strong covalent bonding within C-2 dimers. h-Re2C was derived from the corresponding bulk structure for which we determined the critical thickness for the dynamically stable bulk-derived monolayer structures. In addition, we also investigated the electronic of these two stable structures. Both exhibit metallic behavior and Re-5d orbitals dominate the states around the Fermi level. Due to their ultra high mechanical stability and stiffness, these novel Re-C monolayers can be exploited in various engineering applications.