Mechanical and thermophysical properties of 4d-transition metal mononitrides

Abstract

Abstract The second and third order elastic constants (SOECs and TOECs) of 4d-transition metal mononitrides XN (X: Zr and Nb) have been computed in the temperature range 0 K–500 K using Coulomb and Born–Mayer potential up to second nearest neighbours. In order to investigate the mechanical stability of XN, the computed values of SOECs have been utilized to find out Young’s modulus, bulk modulus, shear modulus, Zener anisotropy and Poisson’s ratio. Furthermore, the SOECs are applied to compute the wave velocities for shear and longitudinal modes of propagation along ⟨100⟩, ⟨110⟩ and ⟨111⟩ crystallographic orientations in the temperature range 100 K–500 K. Temperature dependent Debye average velocity, ultrasonic Grüneisen parameters (UGPs) and Debye temperature have been evaluated. In present work the thermal conductivity of chosen materials has also been evaluated using Morelli-Slack’s approach. Specific heat and total internal thermal energy have been calculated in the temperature range 100 K–500 K on the basis of Debye theory. Thermal relaxation time, acoustic coupling constants and attenuation of ultrasonic waves due to thermo-elastic relaxation and phonon–phonon interaction mechanisms have been calculated in the temperature range 100 K–500 K. The obtained results of present investigation have been compared with available other similar type of materials.