Density functional theory study of structural, mechanical, electronic and optical properties of MoAlX (X = B, C, N and O) compounds

The structural, mechanical, electronic and optical properties of MoAlX (X = B, C, N and O) were studied by density functional theory calculations. The hardness of MoAlB and MoAlN is 20.45 GPa and 9.03 GPa with softer and machinable character as opposed to other borides. The analysis of the band structure and density (DOS) of states shows that MoAlX compounds have a metallic nature. The electronic density difference plots show a spherical charge distribution with ionic bonding in MoAlB and oblate charge distribution in MoAlX (X = C, N and O) indicating covalent bonding. The optical properties of MoAlX are investigated. In the energy range up to ∼15 eV, MoAlX possesses high reflectivity with the strongest absorption in the energy range of 0–35 eV. Furthermore, the plasma frequencies of MoAlX ranges from 21–24 eV and have the ability to change from metallic to dielectric response should the frequency of the incident light be greater than 24 eV.