The role of group III, IV elements in NbAC MAX phases (A = Al, Si, Ga, Ge) and the unusual anisotropic behavior of the electronic and optical properties.

Niobium based NbAlC, NbSiC, NbGeC and NbGaC were investigated by means of density functional theory. Together with the known NbAlC, the role of group III, IV elements in various properties of NbAC (A = Al, Si, Ga, Ge) was systematically investigated, and particularly the bulk moduli, shear moduli, and Young's moduli helped us to approach the ductility. All the studied compounds were found to be mechanically stable, and they also exhibit the metallic nature that results from the Nb-4d states being dominant at the Fermi level.