Density functional theory calculations for magnetic properties of Co3W systems

First-Principles Study of Mechanical and Thermodynamic Properties of Binary and Ternary CoX (X = W and Mo) Intermetallic Compounds

In this study, the structural, elastic, and thermodynamic properties of DO₁₉ and L1₂ structured Co₃X (X = W, Mo or both W and Mo) and μ structured Co₇X₆ were investigated using the density functional theory implemented in the pseudo-potential plane wave. The obtained lattice constants were observed to be in good agreement with the available experimental data. With respect to the calculated mechanical properties and Poisson's ratio, the DO₁₉-Co₃X, L1₂-Co₃X, and μ-Co₇X₆ compounds were noted to be mechanically stable and possessed an optimal ductile behavior; however, L1₂-Co₃X exhibited higher strength and brittleness than DO₁₉-Co₃X. Moreover, the quasi-harmonic Debye-Grüneisen approach was confirmed to be valid in describing the temperature-dependent thermodynamic properties of the Co₃X and Co₇X₆ compounds, including heat capacity, vibrational entropy, and Gibbs free energy. Based on the calculated Gibbs free energy of DO_19-Co₃X and L1₂-Co₇X₆, the phase transformation temperatures for DO_19-Co₃X to L1₂-Co₇X₆ were determined and obtained values were noted to match well with the experiment results.