Insights into the predicted Hf2SN in comparison with the synthesized MAX phase Hf2SC: A comprehensive study

Abstract A comprehensive first principles density functional theory (DFT) investigation of predicted ternary MAX phase Hf2SN is made in comparison with its synthesized carbide counterpart. The studies on structure, thermal shock and microcrack behavior, elastic anisotropy, three stabilities (thermodynamic, mechanical and dynamical), electronic properties, Mulliken population, Vickers hardness, thermal and optical properties of the MAX phases have been carried out. The Fermi surfaces contain both hole- and electron-like topologies which change by replacing C with N. The nature of chemical bonding in both of the MAX phases has been investigated through the elastic anisotropy, site and angular momentum decomposed density of state (DOS), and charge density analysis. Zone center phonon modes, symmetry and activity (IR and Raman) are discussed. The temperature and pressure dependence of thermal properties are studied using the quasi-harmonic Debye model. Lattice thermal conductivity is also investigated as a function of temperature. Both the compounds are mechanically and dynamically stable and elastically anisotropic. Further different optical properties of the two phases are also evaluated for the first time. The reflectivity value is high in the IR-visible region which shows that both the phases could be good candidates to reduce solar heating.