Thermo-elastic and optical properties of molybdenum nitride
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This contribution aims to investigate volume-dependent thermal and mechanical properties of two most studied phases of molybdenum nitride (c-MoN and h-MoN) by means of quasi harmonic approximation approach (QHA) via first-principles calculations up to their melting point and a pressure of 12 GPa. Lattice constants, band gaps and bulk modulus at 0 K match well corresponding experimental measurements. Calculated Bader’s charges indicate that Mo-N bonds exhibit more ionic nature in the cubic MoN phase. Based on estimated Gibbs free energies, the cubic phase presents thermodynamic stability higher than that detected for hexagonl, with no phase transition observed in the selected T-P conditions as detected experimentally. The elastic stiffness coefficients of MoN in hexagonal structure revealed that it is stable elastically; in contrast to the cubic structure. The temperature dependence on the bulk modulus is more profound on the dense cubic phase than on the hexagonal phase. Overall, the two considered structures of molybdenum nitride display very minimal harmonic effects, evidenced by the slight variation of thermal and mechanical properties with the increase of pressure and temperature. The optical conductivity of both phases near a zero photon energy coincides well with their metalic character inferred by their Correponding DOS curves. It is expected that the thermo-elastic properties of saturated molybdenum nitrides reported in this study will aid in the continuous pursuit to enhance their catalytic and mechanical utilizations.
|Publication Type:||Journal Article|
|Murdoch Affiliation:||School of Engineering and Information Technology|
|Publisher:||NRC Research Press|
|Copyright:||© 2016 Canadian Science Publishing|
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