Structural, Electronic, Thermophysical and Optical Investigation of Tetragonal (C11b - CrSi2) Material: A Theoretical Analysis

Chromium disilicide (C11b - CrSi2) have garnered significant attention owing to the novel functions and considerable prospective it holds in ultrahigh temperature engineering applications. The tetragonal structure ( ) being one of the polymorphs of the is investigated in this paper for its thermophysical and optical dielectric properties, which are still lacking in reported studies. The present investigation aim to study the optical real and imaginary parts of dielectric function, joint density of state, the refractive index, and extinction coefficient using first-principle calculations based on density functional theory (DFT). This approach requires knowledge of the atomic species and crystal structure to predict several physical properties of materials. The values of the optimized lattice parameters are in good agreement with experimental results. The diagrams illustrating the electronic band structure and density of state (DOS) plots reveal the compound from the bonding and antibonding characters as a metal in accordance with the experiment. The calculated DOS of tetragonal is 3.61 per eV. In addition, while the equilibrium unit-cell volume, bulk modulus , and bond-lengths (Si–Si and Cr–Si) are in agreement with the available data, the first derivative of the bulk modulus and minimum energy are predicted for future studies. Furthermore, the thermophysical properties of the compound are analyzed at 300 K. The evaluated Debye temperature θ(D) (= 867.87 K) and the high value of (= 284.0 GPa) reflect the feasibility of the material being ductile, while the Debye heat capacity (142.13 J/mol·K) reveals the Dulong-Petit limit. Also, we predict a minimum thermal conductivity of 17.43 mW/K/m. Our study shows that the internal energy, the entropy, and the constant volume heat capacity increase with increasing temperature, while the free energy decreases monotonously with the increase in temperature. Consequently, predictive models for the thermodynamic quantities are herein presented. The calculated optical dielectric properties, such as imaginary and real parts of dielectric function, refractive index, and extinction coefficient, reveal relatively high anisotropy, with indications that the absorption spectrum predominantly depends on the electronic transitions from 3d-Cr and 3p-Si migrations around the Femi level.