Structural, Electronic, Mechanical and Thermodynamic Properties of Half-Metallic Rh 2FeZ (Z = Ga, In) Full Heusler Compounds from First Principles

We report on the structural, electronic, mechanical, and thermodynamic properties of Rh2FeGa and Rh2FeIn full Heusler alloys from first principles. Results for the structural analysis establishes structural stability with a negative formation energy of -0.2175 eV and -0.2082 eVfor Rh2FeGa and Rh2FeIn, respectively. The lattice constants and electronic properties compare favorably with reports from existing  literature. The compounds are both anisotropic and mechanically stable, having checked out with the Born and Huang criteria. Rh2FeIn alloy is more ductile, yet, harder, and stiffer compared to its Rh2FeGa counterpart. The Debye temperatures of 400.124 K and 267. 738 K recorded for Rh2FeGa and Rh2FeIn, respectively, is consistent with the expectation that the main group element's atomic size has an inverse relationship with the Debye temperature. Therefore, indium with the larger atomic size has a lesser Debye temperature. Both compounds obey the Dulong-Petit limit at temperatures between 400 K and 500 K. The specific heat capacity at constant volume 𝐶𝜐 of 96.5 𝐽 𝑚𝑜𝑙−1𝐾−1 and 98 𝐽 𝑚𝑜𝑙−1𝐾 −1 for Rh2FeIn and Rh2FeGa alloys suggests thermodynamic stability of the compounds at moderate  temperatures. Keywords: Density functional theory; Density functional perturbation theory; Half-Heusler compounds; Mechanical Properties;  Thermodynamic properties.