Structural stability, electronic structure, mechanical and optical properties of MAX phase ternary Mo2Ga2C, Mo2GaC and Mo3GaC2 carbides

Abstract

In this article, structural, mechanical, optical and electronic properties of MAX phase ternary Mo2Ga2C, Mo2GaC and Mo3GaC2 carbides are reported. Theoretical calculations are performed by applying OLCAO method within the density functional theory. All three carbides fulfill the structural stability criteria mechanically. The calculated formation energies of all three ternary carbides indicate the structural stability of these carbides. The Mo2GaC and Mo3GaC2 carbides are found less resistant to thermal shock as compared to Mo2Ga2C carbide. Band structure plots reveal conducting behavior of Mo2Ga2C, Mo2GaC and Mo3GaC2 carbides. DOS spectra of Mo2Ga2C, Mo2GaC and Mo3GaC2 carbides show an increasing number of energy states at Fermi level. The calculations of localization index reveal highly delocalized energy states near Fermi level, EF. Effective charge (Q∗) calculations reveal that the Mo atoms have charge losing trend in these carbides. Bond order (BO) calculations show dominant role of covalent nature of Mo–C bonds in the stability and cohesion of all three carbides. Optical behavior of carbides shows anisotropic characteristics up to energy ≤9.0 eV. Above 9.0 eV, carbides exhibit isotropic behavior. Theoretical results suggest that these carbides can of interest for electronic and optical applications.