The investigation of structural, elastic, electronic, vibrational, thermo-physical, and optical properties of hexagonal-type X2N (X = Mn, Tc, and Re) compounds

Abstract The structural, elastic, electronic, phonon, thermo-physical, and optical properties of hexagonal-type X 2 N (X = Mn, Tc, and Re) compounds were studied within the framework of density functional theory using the generalized gradient approximation (GGA). The obtained lattice parameter values were in good agreement with the literature. To investigate the mechanical stability of the studied compounds, the elastic constant values of the three compounds were calculated and from these values, some stiffness constant values such as Bulk (317.49 GPa, 339.29 GPa, and 401.57 GPa for Mn 2 N, Tc 2 N, and Re 2 N, respectively), Young’s (443.14 GPa, 438.11 GPa, and 542.84 GPa for Mn 2 N, Tc 2 N, and Re 2 N, respectively), Shear modulus (174.83 GPa, 170.50 GPa, and 212.93 GPa for Mn 2 N, Tc 2 N, and Re 2 N, respectively) values, and Poisson's ratio (0.27, 0.28, and 0.27 for Mn 2 N, Tc 2 N, and Re 2 N, respectively), were also obtained. According to the calculated elastic constant values, all compounds are mechanically stable and ductile. In addition, the atoms are interconnected by ionic bonding. Electronic band structure calculation was performed to reveal the types of materials. All compounds were found to have metallic character due to the absence of a band gap. Phonon calculation was also performed, which gives information about the dynamic stability of the materials. X 2 N (X = Mn, Tc, and Re) compounds were found to be dynamically stable since they have no negative branches. Thermophysical analyses revealed that Mn 2 N has the highest Debye temperature of 760 K, thus indicating strong chemical bonding and high thermal conductivity. Finally, in optical investigations, the reflectivity, absorption, and optical conductivity properties of X 2 N compounds were evaluated in detail, and it was found that these compounds have high absorption properties in the ultraviolet region.