Investigation on Structural, Elastic and Thermodynamic Properties of MgNi3 Intermetallic Compound Using Density Functional Theory

S. Boucetta Laboratoire d'Elaboration de Nouveaux Matériaux et leurs Caractérisations (ENMC), Département de Physique, Université Ferhat Abbas SETIF 1, 19000, Sétif, Algérie.

Received: April 08, 2019; revised version June 27, 2019; in final form July 17, 2019

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Magnesium based alloys belong to a class of materials, which have recently attracted great interest. In the present work, we report structural, elastic, and thermodynamic properties for the novel intermetallic compound MgNi3 calculated using plane-wave pseudo potential (PW-PP) method within density functional theory (DFT), with local density approximation (LDA) and generalized gradient approximation (GGA). The comparison of the calculated equilibrium lattice constants and experimental data showed very good agreement for both approximations. The elastic constants were determined from a linear fit of the calculated stress-strain function according to Hooke's law. Once the elastic constants were obtained, the bulk modulus B, shear modulus G, Young's modulus E, Poisson's ratio σ anisotropy factor A, and the ratio B/G for MgNi3 compound were deduced using Voigt-Reuss-Hill (VRH) approximation. Our calculated elastic constants indicate that the ground state structure of MgNi3 is mechanically stable. The calculation results also show that this intermetallic crystal is stiff, elastically anisotropic, and ductile material. The Debye temperature is also predicted from elastic constants. The temperature dependence of the enthalpy H, free energy F, entropy S, and heat capacity at constant volume Cv of MgNi3 crystal in a quasi-harmonic approximation are obtained from phonon density of states and discussed for the first report.

DOI:10.12693/APhysPolA.136.479 topics: MgNi3, Elastic properties, Thermodynamic properties, DFT