V impurity effect on the electronic and optical properties of Ti₂C graphene-like: based on DFT

Abstract

The vanadium impurity effects on the electronic and optical properties of titanium carbide graphene-like (Ti₂C:V) are investigated in the density functional theory framework to obtain the corresponding density of states, band structure, dielectric function, energy loss function, reflectivity and absorption spectrum. The electronic and optical results indicated the metallic behavior of the Ti₂C and Ti₂C:V nano-sheets along the graphene sheet (E||x) and the normal direction (E||z), so that the static amount of the real part of the dielectric function is big and the main large peaks of the imaginary one are located at infrared area. For Ti₂C, the results of the real and imaginary parts of the dielectric function in all major peaks are due to the inter-band transitions at high energies, while radiation tends to zero. Absorption is connected to transitions between the occupied and unoccupied states of light which is a mutual effect of electrons; in other words, optical absorption is a result of inter- and intra-band transitions. On Eloss curve of both compounds, there is no energy loss for the case of zero energy, and in the case of E||x, the metallic character of the material is more than E||z case. In addition, in the highest peak in the UV region, the real part of the dielectric function is zero. Unlike the E||z case, reflectivity is almost 100% in E||x case at low energies (less than 1 eV). The increment of absorption in UV region implies the metallic character of Ti₂C:V.