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

Ti2AlB0.5C0.5 and Ti2AlN0.5C0.5 compounds which are called M2AX type MAX phasesreferred to as 211 and have hexagonal crystal structure with conform to P63/mmcspace group, have been examined by using Generalized Gradient Approximation(GGA) in the Density Functional Theory (DFT) as implemented in CASTEP softwarepackage. In this study, the electronic, elastic, and lattice dynamical propertiesof these compounds have been investigated within the ab initio study. Thesecompounds show metallic behavior since there is no band gap in the calculatedelectronic band structures. The estimated elastic constants of these compoundsindicate that they are mechanically stable and their bonding nature is ionic andalso, Ti2AlN0.5C0.5 compund has anisotropic character in mechanically whereasthe behavior of Ti2AlB0.5C0.5 compound is nearly isotropic. Moreover, both of ourcompounds are brittle materials. Also, these compounds are dynamically stablesince there are no soft modes in their plotted phonon dispersion curves.