Structural, electronic, optical, mechanical and thermal properties of TM₅Ge₃C (TM= Cr, Mo and W): A theoretical prediction

Structural, electronic, optical, mechanical and thermal properties of hexagonal TM5Ge3C (TM = Cr, Mo, W) were explored using first-principles calculation. The results demonstrated the thermodynamic and dynamic stability of TM5Ge3C (TM = Cr, Mo and W). Based on the electronic band structure, density of states (DOS), and charge density mapping (CDM), the electronic ground state was determined. The metallic properties of TM5Ge3C (TM = Cr, Mo and W) were evaluated from the DOS and optical properties. According to Poisson's ratio, G/B, C-13-C-44 and C-12-C-66, it was determined that TM5Ge3C (TM = Cr, Mo and W) is ductile. The elastic anisotropy of TM5Ge3C (TM = Cr, Mo and W) was systematically analysed based on the elastic anisotropy index, three-dimensional spatial distributions and planar contours, which show that the elastic anisotropy of TM5Ge3C (TM = Cr, Mo and W) is in the order of W5Ge3C > Mo5Ge3C > Cr5Ge3C. In addition, the sound velocity, Debye temperature and thermal conductivity of TM5Ge3C (TM = Cr, Mo and W) were obtained from the elastic constants and moduli. Finally, the temperature dependence of the Helmholtz free energy, internal energy, entropy, specific heat and thermal expansion coefficient of TM5Ge3C (TM = Cr, Mo and W) were studied in detail. The thermal properties of TM5Ge3C (TM = Cr, Mo and W) were studied systematically, and it was found that the high operating temperature of these compounds makes them suitable for applications such as aero-engine turbine blades.