A simplified approach to predicting thermal expansion anisotropy of solids from first principles: application to the orthorhombic phase of Mo2C

Journal of Materials Science. 2026. No. 61. P. 25452–25470.

Dmitry Vasilyev, Gorev V., Ikhsanov R., Kartsev A.

The orthorhombic phase of 𝛼-Mo2 C is a key component in electrocatalytic applications, as Mo2C-based catalysts can exhibit catalytic performance comparable to or exceeding that of noble metals. Despite its technological relevance, theoretical understanding of the anisotropy in the thermal expansion and related thermoelastic properties of 𝛼-Mo2 C remains limited. In this work, first-principles calculations are employed to systematically investigate the anisotropic physical properties of orthorhombic 𝛼-Mo2 C. A simplified computational framework is introduced to predict anisotropic thermal expansion by explicitly accounting for electronic and vibrational entropy contributions. Using this approach, a comprehensive set of thermodynamic and mechanical properties is evaluated, including elastic constants, bulk, shear, and Young’s moduli, Debye temperature, Poisson’s ratio, sound velocities, elastic anisotropy, heat capacity, and thermal conductivity. The obtained results provide quantitative insight into the thermal expansion anisotropy of orthorhombic-phase materials, with implications for the rational design of Mo2C-based catalytic systems.

Keywords: Debye temperature, Thermal expansion, thermodynamic properties, elastic properties, First-principles calculations, Orthorhombic phase