The First Principles Investigation of Structural, Electronic, Mechanical and Lattice Dynamical Properties of the B and N Doped M2AX Type MAX Phases Ti2AlB0.5C0.5 and Ti2AlN0.5C0.5 Compounds

Abstract

Ti 2 AlB 0.5 C 0.5 and Ti 2 AlN 0.5 C 0.5 compounds which are called M 2 AX type MAX phases referred to as 211 and have hexagonal crystal structure with conform to P6 3 /mmc space group, have been examined by using Generalized Gradient Approximation ( GGA) i n the Density Functional Theory (DFT) as implemented in CASTEP software package . In this study, the electronic, elastic, and lattice dynamical properties of these compounds have been investigated within the ab initio study. These compounds show metallic behavior s ince there is no band gap in the calculated electronic band structures. T he estimated elastic constants of these compounds indicate that they are mechanically stable and their bonding nature is ionic and also, Ti 2 AlN 0.5 C 0.5 compund has anisotropic character in mechanically whereas the behavior of Ti 2 AlB 0.5 C 0.5 compound is nearly isotropic. Moreover, both of our compounds are brittle materials. Also, these compounds are dynamically stable since there are no soft modes in their plotted phonon dispersion curves.